Emilio Fernández

University of Córdoba | UCO · Department of Biochemistry and Molecular Biology

In soil environments where tryptophan may be present due to plant exudation and microbial decay, bacterial indole-3-acetic acid (IAA) biosynthesis from this amino acid can promote plant growth. Chlamydomonas reinhardtii can also convert tryptophan into IAA using the extracellular enzyme LAO1. Accumulation of this auxin may result in algal growth ar...

Interactions between algae and bacteria are ubiquitous and play fundamental roles in nutrient cycling and biomass production. Recent studies have shown that the plant auxin indole acetic acid (IAA) can mediate chemical crosstalk between algae and bacteria, resembling its role in plant-bacterial associations. Here, we report a mechanism for algal ex...

A multispecies bacterial community including Microbacterium fakhimi sp. nov., Stenotrophomonas goyi sp. nov., and Bacillus cereus greatly promoted sustained hydrogen production by the microalga Chlamydomonas reinhardtii when cocultivated in mannitol- and yeast extract-containing medium (up to 313 mLxx L-1). Alga viability was also largely prolonged...

Microbacterium fakhimi sp. nov. has been isolated from a contaminated algal culture ( Chlamydomonas reinhardtii ). Its genome has been fully sequenced (3,753,259 base pairs) and a tentative annotation is provided (3,704 genes). Both, genome information and growth tests suggest that M. fakhimi sp. nov. is auxotroph for biotin and thiamine and unable...

The stability and harmony of ecological niches rely on intricate interactions between their members. During evolution, organisms have developed the ability to thrive in different environments, taking advantage of each other. Among these organisms, microalgae are a highly diverse and widely distributed group of major primary producers whose interact...

The stability and harmony of ecological niches rely on intricated interactions between their members. During evolution, organisms have developed the ability to thrive in different environments taking advantage of each other’s metabolic symphonies. Among them, microalgae are a highly diverse and widely distributed group of major primary producers wh...

Interactions between algae and bacteria are widespread in aquatic and terrestrial ecosystems and play fundamental roles in nutrient cycling and biomass production. However, the chemical basis for many of these interactions is poorly characterized and understood. Recent studies have shown that the plant auxin indole acetic acid (IAA) can mediate che...

Nitrous oxide (N2O) is a powerful greenhouse gas and an ozone-depleting compound whose synthesis and release have traditionally been ascribed to bacteria and fungi. Although plants and microalgae have been proposed as N2O producers in recent decades, the proteins involved in this process have been only recently unveiled. In the green microalga Chla...

In the context of algal wastewater bioremediation, this study has identified a novel consortium formed by the bacterium Methylobacterium oryzae and the microalga Chlamydomonas reinhardtii that greatly increase biomass generation (1.22 g·L⁻¹·d⁻¹), inorganic nitrogen removal (>99%), and hydrogen production (33 mL·L⁻¹) when incubated in media containi...

Phosphorus (P) assimilation and polyphosphate (polyP) synthesis were investigated in Chlamydomonas reinhardtii by supplying phosphate (PO43−; 10 mg P·L−1) to P‐depleted cultures of wildtypes, mutants with defects in genes involved in the vacuolar transporter chaperone (VTC) complex, and VTC‐complemented strains. Wildtype C. reinhardtii assimilated...

Nitrogen (N) is an essential constituent of all living organisms and the main limiting macronutrient. Even when dinitrogen gas is the most abundant form of N, it can only be used by fixing bacteria but is inaccessible to most organisms, algae among them. Algae preferentially use ammonium (NH4+) and nitrate (NO3−) for growth, and the reactions for t...

Biological hydrogen production by microalgae is a potential sustainable, renewable and clean source of energy. However, many barriers limiting photohydrogen production in these microorganisms remain unsolved. In order to explore this potential and make biohydrogen industrially affordable, the unicellular microalga Chlamydomonas reinhardtii is used...

The mitogen activated protein kinases (MAPKs) form part of a signaling cascade through phosphorylation reactions conserved in all eukaryotic organisms. The MAPK cascades are mainly composed by threeproteins, MAPKKKs, MAPKKs and MAPKs. Some signals induce MAPKKK-mediated phosphorylation and activation of MAPKK that phosphorylate and activate MAPK. A...

The conservation of orthologs of most subunits of the origin recognition complex (ORC) has served to propose that the whole complex is common to all eukaryotes. However, various uncertainties have arisen concerning ORC subunit composition in a variety of lineages. Also, it is unclear whether the ancestral diversification of ORC in eukaryotes was ac...

Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains contain NO synthase (NOS), which appears to be absent in all other a...

Free access Link (until March 06, 2019): https://authors.elsevier.com/c/1YOuv7sxn0Rhw1 ABSTRACT: Phytoplankton live under constantly changing environments in which concentrations of inorganic nitrogen can be limiting but organic nitrogen sources (urea, amino acids or peptides) are available. Understanding how algae, as primary producers, assimilat...

Phytoplankton live under constantly changing environments in which concentrations of inorganic nitrogen can be limiting but organic nitrogen sources (urea, amino acids or peptides) are available. Understanding how algae, as primary producers, assimilate organic nitrogen is of eco-physiological importance although such studies are rare. Given geneti...

All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, alde...

Ammonium is an important nitrogen (N) source for living organisms, a key metabolite for pH control, and a potent cytotoxic compound. Ammonium is transported by the widespread AMT-Mep-Rh membrane proteins, and despite their significance in physiological processes, the nature of substrate translocation (NH 3 /NH 4⁺ ) by the distinct members of this f...

Nitrogen assimilation and metabolism are essential processes for all living organisms, yet there is still much to be learnt on how they are regulated. The use of Chlamydomonas reinhardtii as a model system has been instrumental not only in identifying conserved regulation mechanisms that control the nitrogen assimilation pathway, but also in unders...

Molybdenum (Mo) is present as a pterin-cofactor in the active center of plant enzymes catalyzing key steps of nitrogen, carbon, and sulfur metabolisms, making them essential for efficient growth under the diverse environmental conditions. Additionally, legume plants also require Mo for symbiotic nitrogen fixation relying on the activity of the bact...

Nitrogen is a key nutrient for land plants and phytoplankton in terrestrial and aquatic ecosystems. The model alga Chlamydomonas reinhardtii can grow efficiently on several inorganic nitrogen sources (e.g. ammonium, nitrate, nitrite) as well as many amino acids. In this study, we show that Chlamydomonas is unable to use proline, hydroxyproline, and...

Background A recent Commentary article entitled “On the pathways feeding the H2 production process in nutrient-replete, hypoxic conditions” by Dr. Scoma and Dr. Tóth, Biotechnology for Biofuels (2017), opened a very interesting debate about the H2 production photosynthetic-linked pathways occurring in Chlamydomonas cultures grown in acetate-contain...

Molybdenum (Mo) is present in the active center of eukaryotic enzymes as a tricyclic pyranopterin chelate compound forming the Mo Cofactor (Moco). Four Moco containing enzymes are known in eukaryotes, nitrate reductase (NR), sulfite oxidase (SO), xanthine oxidoreductase (XOR), and aldehyde oxidase (AO). A fifth Moco enzyme has been recently identif...

Over the last decades, several studies have reported emissions of nitrous oxide (N2 O) from microalgae cultures and aquatic ecosystems characterized by a high level of algal activity (e.g. eutrophic lakes). As N2 O is a potent greenhouse gas (GHG) and an ozone depleting pollutant, these findings suggest that large scale microalgae cultivation (and...

The mARC (mitochondrial Amidoxime Reducing Component) proteins are recently discovered molybdenum (Mo) Cofactor containing enzymes. They are involved in the reduction of several N-hydroxylated compounds (NHC) and nitrite. Some NHC are prodrugs containing an amidoxime structure or mutagens such as 6-hydroxylaminopurine (HAP). We have studied this pr...

The green alga Chlamydomonas is a valuable model system capable of assimilating different forms of nitrogen (N). Nitrate (NO3-) has a relevant role in plant-like organisms, first as a nitrogen source for growth and second as a signalling molecule. Several modules are necessary for Chlamydomonas to handle nitrate, including transporters, nitrate red...

Nitrate reductase (NR) is a key enzyme for nitrogen acquisition by plants, algae, yeasts, and fungi. Nitrate, its main substrate, is required for signaling and is widely distributed in diverse tissues in plants. In addition, NR has been proposed as an important enzymatic source of nitric oxide (NO). Recently, NR has been shown to play a role in NO...

The ubiquitous signalling molecule Nitric Oxide (NO) is characterized not only by the variety of organisms in which it has been described, but also by the wealth of biological processes that it regulates. In contrast to the expanding repertoire of functions assigned to NO, however, the mechanisms of NO action usually remain unresolved, and genes th...

Alignment of the N terminal part of NON1 with homologous sequences of eight algae proteins. A graphical representation of the alignment is provided in Fig 3. Sequence ID numbers of proteins from the different organisms are (from top to bottom): XP_002950714.1 (Volvox carteri), XP_005847655.1 (Chlorella variabilis), XP_005849673.1 (Chlorella variabi...

Additional information on the complementation experiment. (A) 42.49CG2 expression was quantified in the wild type strain 704 grown in standard media containing 4 mM of NO3- (light grey) or 8 mM of NH4+ (dark grey). Samples were harvested 30 minutes, 1 hour, 3 hours and 24 hours after induction in the two conditions. The means were calculated based...

The influence on NON1 expression of the phosphodiesterase inhibitor IBMX, and the guanylate cyclase inhibitors LY83,583 and ODQ. The 704 parental strain was grown on NH4+ 8 mM medium until the cell culture reached exponential phase, and the cells were washed and transferred to media containing (A) NO3- 100 μM or (B) and (C) NO3−4 mM and NH4+ 1 mM....

List of primers used in this study. (DOCX)

Mean relative expression of candidate genes 42.49CG1, 85.37CG, and 209.82CG in the eight mutant strains. Genotypes were grown in four nitrogen contexts and harvested at four times points per condition (see Materials and Methods). Mean relative expression levels were calculated and presented using the same rationale than in Fig 1D. A threefold cut o...

Details of genes analysed in Fig 1. (DOCX)

The NRT2 transporters mediate High Affinity Nitrate/NitriteTransport (HAN/NiT), which are essential for nitrogen acquisition from these inorganic forms. The NRT2 proteins are encoded by a multigene family in plants, and contain 12 transmembrane-spanning domains. Chlamydomonas reinhardtii has six NRT2, two of which (NRT2.5 and NRT2.4) are located in...

Nitric oxide (NO) is a relevant signal molecule involved in many plant processes. However, the mechanisms and proteins responsible for its synthesis are scarcely known. In most photosynthetic organisms NO synthases have not been identified, and Nitrate Reductase (NR) has been proposed as the main enzymatic NO source, a process that in vitro is also...

Nitrate assimilation is a key process for nitrogen (N) acquisition in green microalgae. Among Chlorophyte algae, Chlamydomonas reinhardtii has resulted to be a good model system to unravel important facts of this process, and has provided important insights for agriculturally relevant plants. In this work, the recent findings on nitrate transport,...

Background: Currently, hydrogen fuel is derived mainly from fossil fuels, but there is an increasing interest in clean and sustainable technologies for hydrogen production. In this context, the ability of some photosynthetic microorganisms, particularly cyanobacteria and microalgae, to produce hydrogen is a promising alternative for renewable, cle...

Nitric oxide (NO) has emerged as an important regulator of the nitrogen assimilation pathway in plants. Nevertheless, this free radical is a double-edged sword for cells due to its high reactivity and toxicity. Hemoglobins, which belong to a vast and ancestral family of proteins present in all kingdoms of life, have arisen as important NO scavenger...

Microalgae are capable of biological H2 photoproduction from water, solar energy, and a variety of organic substrates. Acclimation responses to different nutrient regimes finely control photosynthetic activity and can influence H2 production. Hence, nutrient stresses are an interesting scenario to study H2 production in photosynthetic organisms. In...

Hemoglobins are ubiquitous proteins that sense, store and transport oxygen, but the physiological processes in which they are implicated is currently expanding. Recent examples of previously unknown hemoglobin functions, which include scavenging of the signaling molecule nitric oxide (NO), illustrate how the implication of hemoglobins in different...

Ferredoxin from Chlamydomonas reinhardii has been purified to electrophoretic homogeneity by an easy and fast procedure with a high yield (25 -30 mg/250 g wet weight of cells). An average molecular weight of 11800 was calculated from sedimentation coefficient (1.70 S) and Stokes radius (1.75 nm) data, sodium dodecyl sulfate-electrophoresis, and ami...

Nitrate reductase from mutant 305 of Chlamydomonas reinhardii has been purified about 90-fold and biochem ically characterized. The enzyme can use reduced flavins and viologens as electron donors to reduce nitrate but, unlike the nitrate reductase com plex from its parental wild strain, lacks NAD(P)H-nitrate reductase and NAD(P)H-cytochrome c reduc...

Chlamydomonas reinhardii 104 mutant strain cells contain many NAD(P)H-cytochrome c reductase activities unrelated to nitrate reduction in addition to an NAD(P)H-cytochrom e c reductase related to NAD(P)H-nitrate reductase, which have molecular weights from 37000 to 124000. By combining chromatographic procedures and preparative isoelectric focusing...

The Chlamydomonas reinhardtii NIT2 gene plays a central role in nitrate assimilation, thus nit2 mutants are not able to sense or to use nitrate for growth. NIT2 protein is an RWP-RK-type transcriptional factor related to nodule inception (Nin, NLP) proteins from plants. NIT2 expression is down regulated in ammonium and up regulated under nitrogen d...

Microalgae are receiving increasing attention as alternative production systems for renewable energy such as biofuel. The photosynthetic alga Chlamydomonas reinhardtii is widely recognized as the model system to study all aspects of algal physiology, including the molecular mechanisms underlying the accumulation of starch and triacylglycerol (TAG),...

Members of the plant NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family display protein sequence homology with the SLC15/PepT/PTR/POT family of peptide transporters in animals. In comparison to their animal and bacterial counterparts, these plant proteins transport a wide variety of substrates: nitrate, peptides, amino acids, dicarboxylate...

Nitrate and ammonium are major inorganic nitrogen sources for plants and algae. These compounds are assimilated by means of finely regulated processes at transcriptional and post-translational levels. In Chlamydomonas, the expression of several genes involved in high-affinity ammonium (AMT1.1, AMT1.2) and nitrate transport (NRT2.1) as well as nitra...

The viability of plants relies on molybdenum, which after binding to the organic moiety of molybdopterin forms the molybdenum cofactor (Moco) and acquires remarkable redox properties. Moco is in the active site of critical molybdoenzymes, which use to work as small electron transport chains and participate in N and S metabolism, hormone biosynthesi...

Ketocarotenoids are obtained by the action of the β-carotene ketolase, which catalyses the addition of a keto-group at the C4 position of carotenoids β-ion-rings. Most microalgae and higher plants do not posses the carotene ketolase activity and consequently do not synthesize ketocarotenoids, which are highly demanded as feed supplements and as nut...

The ARC (amidoxime reducing component) proteins are molybdenum cofactor (Moco) enzymes named hmARC1 and hmARC2 (human ARCs [hmARCs]) in humans and YcbX in Escherichia coli. They catalyze the reduction of a broad range of N-hydroxylated compounds (NHC) using reducing power supplied by other proteins. Some NHC are prodrugs or toxic compounds. YcbX co...

ABSTRACT: A method was developed to identify insertional mutants of Chlamydomonas reinhardtii disrupted for selected target genes. The approach relies on the generation of thousands of transformants followed by PCR-based screenings that allow for identification of strains harboring the introduced marker gene within specific genes of interest. Our r...

Molybdenum (Mo) is a very scarce element whose function is fundamental in living beings within the active site of Mo-oxidoreductases, playing key roles in the metabolism of N, S, purines, hormone biosynthesis, transformation of drugs and xenobiotics, etc. In eukaryotes, each step from Mo acquisition until its incorporation into a biologically activ...

Almost all living organisms need to obtain molybdenum from the external medium to achieve essential processes for life. Activity of important enzymes such as sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and nitrate reductase is strictly dependent on the presence of Mo in its active site. Cells take up Mo in the form of the oxianion mo...

The assimilation of inorganic nitrogen is an essential process for all plant-like organisms. In the presence of ammonium and nitrate as nitrogen sources, Chlamydomonas reinhardtii preferentially assimilates ammonium and represses the nitrate assimilation pathway through an unknown mechanism that in part involves the guanylate cyclase CYG56. It is d...

The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre-gametes mostly used a low-affinity system (LATS) component, but gametes obtained after light treatment of N-deprived pre-gametes expressed both LATS and high-affinity...

Nitrate assimilation in plants and related organisms is a highly regulated and conserved pathway in which the enzyme nitrate reductase (NR) occupies a central position. Although some progress has been made in understanding the regulation of the protein, transcriptional regulation of the NR gene (NIA1) is poorly understood. This work describes a mec...

Homeostasis of three elements nickel, molybdenum and chloride is analysed. These micronutrients, at amounts varying in orders of magnitude, fulfil important cell functions. In general terms, cells use similar strategies to ensure that the elements are within physiological ranges avoiding high toxic concentrations. These strategies correspond to spe...

Nitrate is an essential nutrient, and is involved in many adaptive responses of plants, such as localized proliferation of roots, flowering or stomatal movements. How such nitrate-specific mechanisms are regulated at the molecular level is poorly understood. Although the Arabidopsis ANR1 transcription factor appears to control stimulation of latera...

Molybdenum is an essential element for almost all living beings, which, in the form of a molybdopterin-cofactor, participates in the active site of enzymes involved in key reactions of carbon, nitrogen, and sulfur metabolism. This metal is taken up by cells in form of the oxyanion molybdate. Bacteria acquire molybdate by an ATP-binding-cassette (AB...