Helena Santos

New University of Lisbon, Lisboa, Lisbon, Portugal

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Publications (174)562.75 Total impact

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    ABSTRACT: The fluorescence of the four tyrosines of α-synuclein (Syn) was used for probing the earliest events preceding the fibrillation of Syn, during the onset of the so-called lag-time of fibrillation. Steady-state fluorescence experiments revealed an increase in the fluorescence intensity (FI) for Syn solutions at pH values 3 and 2, in comparison with pH7, and fluorescence decays indicated that the FI increase did not result from suppression of excited-state proton transfer from the tyrosines to aspartates and glutamates, exposure of tyrosines to more hydrophobic environments, or reduction of homo-energy transfer. Instead, the FI increase was due to changes in the population of the tyrosine rotamers at low pH values. Stopped-flow experiments (pH-jumps) showed that the FI enhancement involves two processes: a fast (sub-7ms) intramolecular (concentration-independent) process, which we assign to the protein collapse at low pH, and a slower intermolecular (concentration-dependent) process of protein dimerization/oligomerization, starting at 4-10s after acidification. To the best of our knowledge, this is the first work on the experimental detection of these earliest processes in the fibrillation of Syn.
    No preview · Article · Nov 2015 · Journal of photochemistry and photobiology. B, Biology
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    ABSTRACT: 2,3-Butanediol is an important bulk chemical with a wide range of applications. In bacteria, this metabolite is synthesised from pyruvate via a three-step pathway involving α-acetolactate synthase, α-acetolactate decarboxylase and 2,3-butanediol dehydrogenase. Thus far, the best producers of 2,3-butanediol are pathogenic strains, hence, the development of more suitable organisms for industrial scale fermentation is needed. Herein, 2,3-butanediol production was engineered in the Generally Regarded As Safe (GRAS) organism Corynebacterium glutamicum. A two-stage fermentation process was implemented: first, cells were grown aerobically on acetate; in the subsequent production stage cells were used to convert glucose into 2,3-butanediol under non-growing and oxygen-limiting conditions. A gene cluster, encoding the 2,3-butanediol biosynthetic pathway of Lactococcus lactis, was assembled and expressed in background strains, C. glutamicum ΔldhA, C. glutamicum ΔaceEΔpqoΔldhA and C. glutamicum ΔaceEΔpqoΔldhAΔmdh, tailored to minimize pyruvate-consuming reactions, i.e., to prevent carbon loss in lactic, acetic and succinic acids. Producer strains were characterized in terms of activity of the relevant enzymes in the 2,3-butanediol forming pathway, growth, and production of 2,3-butanediol under oxygen-limited conditions. Productivity was maximized by manipulating the aeration rate in the production phase. The final strain, C. glutamicum ΔaceEΔpqoΔldhAΔmdh(pEKEx2-als,aldB,P tuf butA), under optimized conditions produced 2,3-butanediol with a 0.66 mol mol −1 yield on glucose, an overall productivity of 0.2 g L −1 h −1 and a titer of 6.3 g L −1 . We have successfully developed C. glutamicum into an efficient cell factory for 2,3-butanediol production. The use of the engineered strains as a basis for production of acetoin, a widespread food flavour, is proposed.
    Full-text · Article · Oct 2015 · Microbial Cell Factories
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    ABSTRACT: Phosphatidylinositol is critical for intracellular signalling and anchoring of carbohydrates and proteins to outer cellular membranes. The defining step in phosphatidylinositol biosynthesis is catalysed by CDP-alcohol phosphotransferases, transmembrane enzymes that use CDP-diacylglycerol as donor substrate for this reaction, and either inositol in eukaryotes or inositol phosphate in prokaryotes as the acceptor alcohol. Here we report the structures of a related enzyme, the phosphatidylinositol-phosphate synthase from Renibacterium salmoninarum, with and without bound CDP-diacylglycerol to 3.6 and 2.5 Å resolution, respectively. These structures reveal the location of the acceptor site, and the molecular determinants of substrate specificity and catalysis. Functional characterization of the 40%-identical ortholog from Mycobacterium tuberculosis, a potential target for the development of novel anti-tuberculosis drugs, supports the proposed mechanism of substrate binding and catalysis. This work therefore provides a structural and functional framework to understand the mechanism of phosphatidylinositol-phosphate biosynthesis.
    Full-text · Article · Oct 2015 · Nature Communications
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    ABSTRACT: Functional metagenomic screening strategies, which are independent of known sequence information, can lead to the identification of truly novel genes and enzymes. Since E. coli has been used exhaustively for this purpose as a host, it is important to establish alternative expression hosts and to use them for functional metagenomic screening for new enzymes. In this study we show that Thermus thermophilus HB27 is an excellent screening host and can be used as an alternative provider of truly novel biocatalysts. In a previous study we constructed the mutant strain BL03 that was no longer able to grow on defined minimal medium supplemented with tributyrin as the sole carbon source and could be used as a host to screen for metagenomic DNA fragments that could complement growth on tributyrin. Several thousand single fosmid clones from thermophilic metagenomic libraries from heated compost and hot spring water samples were subjected to a comparative screening for esterase activity in both T. thermophilus strain BL03 and E. coli EPI300. We scored a greater number of active clones in the thermophilic bacterium than in the mesophilic E. coli. From all clones functionally screened in E. coli, only two thermostable α/β-fold hydrolase enzymes with high amino acid sequence similarity to already characterized enzymes were identifiable. In contrast, five further fosmids were found that conferred lipolytic activities in T. thermophilus. Four open reading frames (ORFs) were found which did not share significant similarity to known esterase enzymes. Two of the genes were expressed in both hosts and the novel thermophilic esterases, which based on their primary structures could not be assigned to known esterase or lipase families, were purified and preliminarily characterized. Our work underscores the benefit of using additional screening hosts other than E. coli for the identification of novel biocatalysts with industrial relevance.
    Full-text · Article · Apr 2015 · Frontiers in Microbiology
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    ABSTRACT: The solute pool of the actinobacterium Rubrobacter xylanophilus has been investigated as a function of the growth temperature and concentration of NaCl in the medium (Empadinhas et al. Extremophiles 11: 667–673, 2007). Changing the carbon source from glucose to maltose in a minimal growth medium led to the accumulation of an unknown organic compound whose structure was investigated by NMR and confirmed by chemical synthesis in the present study as: (2R)-2-(1-O-α-d-mannopyranosyl)-3-(1-O-α-d-glucopyranosyl)-d-glycerate (MGlyG). In addition to this newly identified diglycoside, the solute pool of R. xylanophilus included trehalose, mannosylglycerate, di-myo-inositol phosphate and di-N-acetyl-glucosamine phosphate. The structure of MGlyG was established by NMR and confirmed by chemical synthesis. The availability of g-amounts of the synthetic material allowed us to perform stabilization tests on three model enzymes (malate dehydrogenase, staphylococcal nuclease, and lysozyme), and compare the efficacy of MGlyG with other natural glyceryl glycosides, such as α-d-mannosyl-d-glycerate, α-d-glucosyl-d-glycerate and α-d-glucosyl-(1 → 6)-α-d-glucosyl-(1 → 2)-d-glycerate.
    No preview · Article · Jan 2015 · Extremophiles
  • Carla D Jorge · Nuno Borges · Helena Santos
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    ABSTRACT: We describe a novel biosynthetic pathway for glycerophosphoinositides in Rhodothermus marinus in which inositol is activated by CTP; this is unlike all known pathways, which involve activation of the lipid group instead. This work was motivated by the detection in the R. marinus genome of a gene with high similarity to CTP:L-myo-inositol-1-phosphate cytidylyltransferase, the enzyme that synthesizes CDP-inositol, a metabolite only known in the synthesis of di-myo-inositol phosphate. However, this solute is absent in R. marinus. The fate of radiolabeled CDP-inositol was investigated in cell extracts to reveal that radioactive inositol was incorporated into the chloroform-soluble fraction. Mass spectrometry showed that the major lipid product has a molecular mass of 810 Da and contains inositol phosphate and alkyl chains attached to glycerol by ether bonds. The occurrence of ether-linked lipids is rare in bacteria and has not been described previously in R. marinus. The relevant synthase was identified by functional expression of the candidate gene in Escherichia coli. The enzyme catalyses the transfer of L-myo-inositol-1-phosphate from CDP-inositol to dialkylether glycerol yielding dialkylether-glycerophosphoinositol. Database searching showed homologous proteins in two bacterial classes, Sphingobacteria and Alphaproteobacteria. This is the first report of the involvement of CDP-inositol in phospholipid synthesis. This article is protected by copyright. All rights reserved.
    No preview · Article · Dec 2014 · Environmental Microbiology
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    ABSTRACT: Halophilic and halotolerant microorganisms adapted to thrive in hot environments accumulate compatible solutes that usually have a negative charge either associated with a carboxylic group or a phosphodiester unit. Mannosylglycerate (MG) has been detected in several members of (hyper)thermophilic bacteria and archaea, in which it responds primarily to osmotic stress. The outstanding ability of MG to stabilize protein structure in vitro as well as in vivo has been convincingly demonstrated. These findings led to an increasingly supported link between MG and microbial adaptation to high temperature. However, the accumulation of MG in many red algae has been known for a long time, and the peculiar distribution of MG in such distant lineages was intriguing. Knowledge on the biosynthetic machinery together with the rapid expansion of genome databases allowed for structural and phylogenetic analyses and provided insight into the distribution of MG. The two pathways for MG synthesis have distinct evolutionary histories and physiological roles: in red algae MG is synthesised exclusively via the single-step pathway and most probably is unrelated with stress protection. In contrast, the two-step pathway is strongly associated with osmoadaptation in (hyper)thermophilic prokaryotes. The phylogenetic analysis of the two-step pathway also reveals a second cluster composed of fungi and mesophilic bacteria, but MG has not been demonstrated in members of this cluster; we propose that the synthase is part of a more complex pathway directed at the synthesis of yet unknown molecules containing the mannosyl-glyceryl unit.
    No preview · Article · Aug 2014 · Extremophiles
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    ABSTRACT: Phospholipids have major roles in the structure and function of all cell membranes. Most integral membrane proteins from the large CDP-alcohol phosphatidyltransferase family are involved in phospholipid biosynthesis across the three domains of life. They share a conserved sequence pattern and catalyse the displacement of CMP from a CDP-alcohol by a second alcohol. Here we report the crystal structure of a bifunctional enzyme comprising a cytoplasmic nucleotidyltransferase domain (IPCT) fused with a membrane CDP-alcohol phosphotransferase domain (DIPPS) at 2.65 Å resolution. The bifunctional protein dimerizes through the DIPPS domains, each comprising six transmembrane α-helices. The active site cavity is hydrophilic and widely open to the cytoplasm with a magnesium ion surrounded by four highly conserved aspartate residues from helices TM2 and TM3. We show that magnesium is essential for the enzymatic activity and is involved in catalysis. Substrates docking is validated by mutagenesis studies, and a structure-based catalytic mechanism is proposed.
    Full-text · Article · Jun 2014 · Nature Communications
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    ABSTRACT: The nutritionally versatile soil bacterium Acinetobacter baylyi ADP1 copes with salt stress by the accumulation of compatible solutes, a strategy that is widespread in nature. This bacterium synthesizes the sugar alcohol mannitol de novo in response to osmotic stress. In a previous study, we identified MtlD, a mannitol-1-phosphate dehydrogenase, which is essential for mannitol biosynthesis and which catalyzes the first step in mannitol biosynthesis, the reduction of fructose-6-phosphate (F-6-P) to the intermediate mannitol-1-phosphate (Mtl-1-P). Until now, the identity of the second enzyme, the phosphatase that catalyzes the dephosphorylation of Mtl-1-P to mannitol, was elusive. Here we show that MtlD has a unique sequence among known mannitol-1-phosphate dehydrogenases with a haloacid dehalogenases (HAD)-like phosphatase domain at the N-terminus. This domain is indeed shown to have a phosphatase activity. Phosphatase activity is strictly Mg(2+) dependent. NMR analysis revealed that purified MtlD catalyzes not only reduction of F-6-P but also dephosphorylation of Mtl-1-P. MtlD of A. baylyi is the first bifunctional enzyme of mannitol biosynthesis that combines Mtl-1-P dehydrogenase and phosphatase activities in a single polypeptide chain. Bioinformatic analysis revealed that the bifunctional enzyme is wide-spread among Acinetobacter strains but only rarely present in other phylogenetic tribes.
    No preview · Article · May 2014 · Environmental Microbiology
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    ABSTRACT: Marine hyperthermophiles accumulate small organic compounds, known as compatible solutes, in response to supra-optimal temperature or salinity. Pyrococcus furiosus is a hyperthermophilic archaeon that grows optimally at temperatures near 100°C. This organism accumulates mannosylglycerate (MG) and di-myo-inositol phosphate (DIP) in response to osmotic and heat stress, respectively. It has been assumed that MG and DIP are involved in cell protection; however, firm evidence for the roles of these solutes in stress adaptation is still missing, largely due to the lack of genetic tools to produce suitable mutants of hyperthermophiles. Recently, such tools were developed for P. furiosus, making this organism an ideal target for that purpose. In this work, genes coding for the synthases in the biosynthetic pathways of MG and DIP were deleted by double-crossover homologous recombination. The growth profiles and solute patterns of the two mutants and the parent strain were investigated under optimal growth conditions and also at a supra-optimal temperature and NaCl concentration. DIP was a suitable replacement for MG during heat stress, but substitution of MG by DIP and aspartate led to a less efficient growth under osmotic stress. The results suggest that the cascade of molecular events leading to MG synthesis is tuned for osmotic adjustment, while the machinery for induction of DIP synthesis responds to either stress agent. MG is as effective as DIP to protect cells against heat, despite the finding that DIP consistently increases in response to heat stress in the nine (hyper)thermophiles examined thus far.
    Preview · Article · May 2014 · Applied and Environmental Microbiology
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    ABSTRACT: Halobacillus halophilus, a moderately halophilic bacterium isolated from salt marshes, produces various compatible solutes to cope with osmotic stress. Glutamate and glutamine are dominant compatible solutes at mild salinities. Glutamine synthetase activity in cell suspensions of Halobacillus halophilus wild type was shown to be salt dependent and chloride modulated. A possible candidate to catalyze glutamine synthesis is glutamine synthetase A2, whose transcription is stimulated by chloride. To address the role of GlnA2 in the biosynthesis of the osmolytes glutamate and glutamine, a deletion mutant (ΔglnA2) was generated and characterized in detail. We compared the pool of compatible solutes and performed transcriptional analyses of the principal genes controlling the solute production in the wild type strain and the deletion mutant. These measurements did not confirm the hypothesized role of GlnA2 in the osmolyte production. Most likely the presence of another, yet to be identified enzyme has the main contribution in the measured activity in crude extracts and probably determines the total chloride-modulated profile. The role of GlnA2 remains to be elucidated.
    Full-text · Article · Apr 2014 · Frontiers in Microbiology
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    ABSTRACT: Wild-type Corynebacterium glutamicum produces a mixture of lactic, succinic, and acetic acids from glucose under oxygen deprivation. We investigated the effect of CO2 on the production of organic acids in a two-stage process: cells were grown aerobically in glucose, and subsequently, organic acid production by nongrowing cells was studied under anaerobic conditions. The presence of CO2 caused up to a 3-fold increase in the succinate yield (1 mol per mol of glucose) and about 2-fold increase in acetate, both at the expense of l-lactate production; moreover, dihydroxyacetone formation was abolished. The redistribution of carbon fluxes in response to CO2 was estimated by using 13C-labeled glucose and 13C nuclear magnetic resonance (NMR) analysis of the labeling patterns in end products. The flux analysis showed that 97% of succinate was produced via the reductive part of the tricarboxylic acid cycle, with the low activity of the oxidative branch being sufficient to provide the reducing equivalents needed for the redox balance. The flux via the pentose phosphate pathway was low (∼5%) regardless of the presence or absence of CO2. Moreover, there was significant channeling of carbon to storage compounds (glycogen and trehalose) and concomitant catabolism of these reserves. The intracellular and extracellular pools of lactate and succinate were measured by in vivo NMR, and the stoichiometry (H+:organic acid) of the respective exporters was calculated. This study shows that it is feasible to take advantage of natural cellular regulation mechanisms to obtain high yields of succinate with C. glutamicum without genetic manipulation.
    No preview · Article · Mar 2014 · Applied and Environmental Microbiology
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    ABSTRACT: Details of the beamline, detector and overall Wilson B in the article by Nogly et al. (2012, Acta Cryst. F68, 1113-1115) are corrected.
    Full-text · Article · Nov 2013 · Acta Crystallographica Section F Structural Biology and Crystallization Communications
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    ABSTRACT: The first structure of a bacterial α-phosphoglucomutase with an overall fold similar to eukaryotic phosphomannomutases is reported. Unlike most α-phosphoglucomutases within the α-D-phosphohexomutase superfamily, it belongs to subclass IIb of the haloacid dehalogenase superfamily (HADSF). It catalyzes the reversible conversion of α-glucose 1-phosphate to glucose 6-phosphate. The crystal structure of α-phosphoglucomutase from Lactococcus lactis (APGM) was determined at 1.5 Å resolution and contains a sulfate and a glycerol bound at the enzyme active site that partially mimic the substrate. A dimeric form of APGM is present in the crystal and in solution, an arrangement that may be functionally relevant. The catalytic mechanism of APGM and its strict specificity towards α-glucose 1-phosphate are discussed.
    Full-text · Article · Oct 2013 · Acta Crystallographica Section D Biological Crystallography
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    ABSTRACT: The effect of pH on the glucose metabolism of non-growing cells of L. lactis MG1363 was studied by in vivo NMR in the range 4.8 to 6.5. Immediate pH effects on glucose transporters and/or enzyme activities were distinguished from transcriptional/translational effects by using cells grown at the optimal pH of 6.5 or pre-adjusted to low pH by growth at 5.1. In cells grown at pH 5.1, glucose metabolism proceeds at a rate 35% higher than in non-adjusted cells at the same pH. Besides the upregulation of stress-related genes (such as dnaK and groEL), cells adjusted to low pH overexpressed H(+)-ATPase subunits as well as glycolytic genes. At sub-optimal pHs, the total intracellular pool of lactic acid reached approximately 500 mM in cells grown at optimal pH and about 700 mM in cells grown at pH 5.1. These high levels, together with good pH homeostasis (internal pH always above 6), imply intracellular accumulation of the ionized form of lactic acid (lactate anion), and the concomitant export of the equivalent protons. The average number, n, of protons exported with each lactate anion was determined directly from the kinetics of accumulation of intra- and extracellular lactic acid as monitored online by (13)C-NMR. In cells non-adjusted to low pH, n varies between 2 and 1 during glucose consumption, suggesting an inhibitory effect of intracellular lactate on proton export. We confirmed that extracellular lactate did not affect the lactate: proton stoichiometry. In adjusted cells, n was lower and varied less, indicating a different mix of lactic acid exporters less affected by the high level of intracellular lactate. A qualitative model for pH effects and acid stress adaptation is proposed on the basis of these results.
    Full-text · Article · Jul 2013 · PLoS ONE
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    ABSTRACT: BACKGROUND: Protein aggregation in the brain is a central hallmark in many neurodegenerative diseases. In Parkinson's disease, α-synuclein (α-Syn) is the major component of the intraneuronal inclusions found in the brains of patients. Current therapeutics is merely symptomatic, and there is a pressing need for developing novel therapies. Previously we showed that mannosylglycerate (MG), a compatible solute typical of marine microorganisms thriving in hot environments, is highly effective in protecting a variety of model proteins against thermal denaturation and aggregation in vitro. METHODS: Saccharomyces cerevisiae cells expressing eGFP-tagged α-Syn, were further engineered to synthesize MG. The number of cells with fluorescent foci was assessed by fluorescence microscopy. Fluorescence spectroscopy and transmission electron microscopy were used to monitor fibril formation in vitro. RESULTS: We observed a 3.3-fold reduction in the number of cells with α-Syn foci and mild attenuation of α-Syn-induced toxicity. Accordingly, sucrose gradient analysis confirmed a clear reduction in the size-range of α-Syn species in the cells. MG did not affect the expression levels of α-Syn or its degradation rate. Moreover, MG did not induce molecular chaperones (Hsp104, Hsp70 and Hsp40), suggesting the implication of other mechanisms for α-Syn stabilization. MG also inhibited α-Syn fibrillation in vitro. CONCLUSIONS: MG acts as a chemical chaperone and the stabilization mechanism involves direct solute/protein interactions. GENERAL SIGNIFICANCE: This is the first demonstration of the anti-aggregating ability of MG in the intracellular milieu. The work shows that MG is a good candidate to inspire the development of new drugs for protein-misfolding diseases.
    No preview · Article · Apr 2013 · Biochimica et Biophysica Acta
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    ABSTRACT: Double quantum and triple quantum filtered (23)Na nuclear magnetic resonance techniques were used to characterise in detail the isotropic and anisotropic binding and dynamics of intra- and extracellular Na(+) in different cellular systems, in the absence and presence of Li(+). The kinetics of Li(+) influx by different cell types was evaluated. At steady state, astrocytes accumulated more Li(+) than red blood cells (RBCs), while a higher intracellular Li(+) concentration was found in chromaffin than in SH-SY5Y cells. Anisotropic and isotropic motions were detected for extracellular Na(+) in all cellular systems studied. Isotropic intracellular Na(+) motions were observed in all types of cells, while anisotropic Na(+) motions in the intracellular compartment were only detected in RBCs. (23)Na triple quantum signal efficiency for intracellular Na(+) was SH-SY5Y > chromaffin > RBCs, while the reverse order was observed for the extracellular ions. (23)Na double quantum signal efficiency for intracellular Na(+) was non-zero only in RBCs, and for extracellular Na(+) the order RBCs > chromaffin > SH-SY5Y cells was observed. Li(+) loading generally decreased intracellular Na(+) isotropic movements in the cells, except for astrocytes incubated with a low Li(+) concentration and increased anisotropic intracellular Na(+) movements in RBCs. Li(+) effects on the extracellular signals were more complex, reflecting Li(+)/Na(+) competition for isotropic and anisotropic binding sites at the extracellular surface of cell membranes and also at the surface of the gel used for cell immobilisation. These results are relevant and contribute to the interpretation of the in vivo pharmacokinetics and sites of Li(+) action.
    No preview · Article · Apr 2013 · Biophysics of Structure and Mechanism
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    ABSTRACT: The lactic acid bacteria (LAB) are a functionally related group of low-GC Gram-positive bacteria known essentially for their roles in bioprocessing of foods and animal feeds. Due to extensive industrial use and enormous economical value, LAB have been intensively studied and a large body of comprehensive data on their metabolism and genetics was generated throughout the years. This knowledge has been instrumental in the implementation of successful applications in the food industry, such as the selection of robust starter cultures with desired phenotypic traits. The advent of genomics, functional genomics and high-throughput experimentation combined with powerful computational tools currently allows for a systems level understanding of these food industry workhorses. The technological developments in the last decade have provided the foundation for the use of LAB in applications beyond the classic food fermentations. Here we discuss recent metabolic engineering strategies to improve particular cellular traits of LABand to design LAB cell factories for the bioproduction of added value chemicals.
    No preview · Article · Apr 2013 · Biotechnology advances
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    ABSTRACT: The nutritionally versatile and naturally competent soil bacterium Acinetobacter baylyi copes with salt stress by the accumulation of compatible solutes. NMR analyses revealed that cells amassed glutamate and the rather unusual sugar alcohol mannitol upon an increase of the external NaCl concentration. To unravel the path of mannitol biosynthesis, the genome was inspected for genes potentially involved in its biosynthesis. A gene encoding a potential mannitol-1-phosphate dehydrogenase (mtlD) was identified in the genome of A. baylyi. Expression of mtlD was highly induced at high salinity. mtlD was overexpressed and the purified protein indeed produced mannitol-1-phosphate from fructose-6-phosphate. The enzyme preferred NADPH over NADH and the specific activity of fructose-6-phosphate reduction with NADPH was 130 U mg(-1) . Enzymatic activity was strictly salt-dependent. Deletion of mtlD resulted in a complete loss of salt-dependent mannitol biosynthesis. We provide clear evidence that osmo-induced synthesis of the compatible solute mannitol is by a two-step pathway and that the mannitol-1-phosphate dehydrogenase mediating the first step of this pathway is regulated by salinity on the transcriptional as well as on the activity level.
    Full-text · Article · Jan 2013 · Environmental Microbiology
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    ABSTRACT: The accumulation of organic solutes was investigated in the thermophilic bacteria Persephonella marina and Marinitoga piezophila, two representatives of the deepest lineages in the domain Bacteria. These organisms grow optimally at around 70 °C in medium containing 3 % NaCl. A new disaccharide, accumulating in Persephonella marina, was identified as α(1-6)glucosyl-α(1-2)glucosylglycerate (GGG), by nuclear magnetic resonance. This identification was validated by comparison with the spectra of the compound obtained by chemical synthesis. Besides GGG, the solute pool of Persephonella marina comprised β-glutamate, di-myo-inositol-1,3'-phosphate and 2-O-α-glucosylglycerate. In contrast, amino acids such as α-glutamate, proline and alanine were the dominant components of the solute pool of Marinitoga piezophila and sugar derivatives were absent. The ability of GGG to protect protein structure against heat denaturation was assessed using model proteins. A genomic search for the biosynthetic pathways of known ionic solutes in Aquificales and Thermotogales shows the inability of this analysis to predict the nature of compatible solutes and underlines the need for efficient cultivation techniques.
    Full-text · Article · Nov 2012 · Extremophiles

Publication Stats

4k Citations
562.75 Total Impact Points


  • 1996-2015
    • New University of Lisbon
      • • Institute of Chemical and Biological Technology (ITQB)
      • • Department of Chemistry
      Lisboa, Lisbon, Portugal
  • 1994-2010
    • University of Groningen
      • • Department of Molecular Genetics
      • • Department of Microbial Ecology
      Groningen, Province of Groningen, Netherlands
  • 2009
    • Goethe-Universität Frankfurt am Main
      • Institut für Molekulare Biowissenschaften
      Frankfurt am Main, Hesse, Germany
    • University of Leeds
      • School of Physics and Astronomy
      Leeds, England, United Kingdom
  • 2008
    • Spanish National Research Council
      • Biological Research Centre
      Madrid, Madrid, Spain
  • 2003-2008
    • Universität Konstanz
      • Department of Biology
      Constance, Baden-Württemberg, Germany
  • 1998-2006
    • University of Coimbra
      • Department of Chemistry
      Coímbra, Coimbra, Portugal
  • 1982-2005
    • Instituto Técnico y Cultural
      Santa Clara de Portugal, Michoacán, Mexico
  • 2002
    • NIZO food research
      Ede, Gelderland, Netherlands
  • 1999
    • MIT Portugal
      Porto Salvo, Lisbon, Portugal