Andres Esteban Marcoleta

Andres Esteban Marcoleta
University of Chile · Facultad de Ciencias

Doctor en Microbiología
Assistant Professor, Faculty of Science, Universidad de Chile

About

40
Publications
33,924
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
452
Citations
Introduction
With our Grupo de Microbiología Integrativa, we use diverse experimental and computational approaches to reach a holistic understanding of different phenomena where microorganisms are key players. Some current topics include host-microbe interactions, bacterial pathogenesis and surrogate host models such as zebrafish and Dictyostelium discoideum, cancer, microbial genetics and evolutionary genomics, horizontal gene transfer, microbial amyloids, antibiotic resistance, and Antarctic microbiology.
Additional affiliations
January 2019 - April 2020
University of Chile
Position
  • Professor (Assistant)
January 2012 - December 2018
University of Chile
Position
  • PostDoc Position
Education
March 2006 - January 2011
University of Chile
Field of study
  • Doctorado en Microbiología
March 2001 - January 2006
University of Chile
Field of study
  • Ingeniería en Biotecnología Molecular

Publications

Publications (40)
Article
The rise of multiresistant bacterial pathogens is currently one of the most critical threats to global health, encouraging a better understanding of the evolution and spread of antimicrobial resistance. In this regard, the role of the environment as a source of resistance mechanisms remains poorly understood. Moreover, we still know a minimal part...
Article
Full-text available
The prognosis of severe COVID-19 patients has motivated research communities to uncover mechanisms of SARS-CoV-2 pathogenesis also on a regional level. In this work, we aimed to understand the immunological dynamics of severe COVID-19 patients with different degrees of illness, and upon long-term recovery. We analyzed immune cellular subsets and SA...
Preprint
Full-text available
The prognosis of severe COVID-19 patients has motivated research communities to uncover mechanisms of SARS-CoV-2 pathogenesis also on a regional level. In this work, we aimed to understand the immunological dynamics of severe COVID-19 patients with different degrees of illness, and upon long-term recovery. We analyzed immune cellular subsets and SA...
Preprint
The rising of multiresistant bacterial pathogens is currently one of the most critical threats to global health, demanding a better understanding of the origin and spread of antibiotic resistance. In this regard, the resistome hosted by the microbiota from natural and remote environments remains poorly explored. Moreover, little is known about the...
Preprint
Full-text available
The evolution of traits including antibiotic resistance, virulence, and increased fitness in Klebsiella pneumoniae and related species has been linked to the acquisition of mobile genetic elements through horizontal transfer. Among them, genomic islands (GIs) preferentially integrating at genes encoding tRNAs and the tmRNA (t(m)DNAs) would be signi...
Article
Full-text available
One of the approaches to address cancer treatment is to develop new drugs not only to obtain compounds with less side effects, but also to have a broader set of alternatives to tackle the resistant forms of this pathology. In this regard, growing evidence supports the use of bacteria-derived peptides such as bacteriocins, which have emerged as prom...
Article
Full-text available
The increasing detection of virulent and/or multidrug resistant bacterial strains makes necessary the development of new antimicrobial agents acting through novel mechanisms and cellular targets. A good choice are molecules aimed to interfere with the cell division machinery or divisome, which is indispensable for bacterial survival and propagation...
Article
Full-text available
We obtained the complete genome sequence of the psychrotolerant extremophile Pseudomonas sp. MPC6, a natural Polyhydroxyalkanoates (PHAs) producing bacterium able to rapidly grow at low temperatures. Genomic and phenotypic analyses allowed us to situate this isolate inside the Pseudomonas fluorescens phylogroup of pseudomonads as well as to reveal...
Article
Full-text available
Extreme environments are a unique source of microorganisms encoding metabolic capacities that remain largely unexplored. In this work, we isolated two Antarctic bacterial strains able to produce poly(3-hydroxyalkanoates) (PHAs), which were classified after 16S rRNA analysis as Pseudomonas sp. MPC5 and MPC6. The MPC6 strain presented nearly the same...
Chapter
Full-text available
Amyloids are supramolecular protein assemblies based on fibrillar arrangements of β‐sheets that were first found as linked to neurodegenerative and systemic human diseases. However, there is now overwhelming evidence on alternative roles of amyloids as functional assemblies and as epigenetic determinants of beneficial traits, both in Fungi and Meta...
Chapter
Important features of host–pathogen interactions have been discovered using nonmammalian hosts. Therefore, model organisms such as the nematode Caenorhabditis elegans, the social amoeba Dictyostelium discoideum, and zebrafish ( Danio rerio ) have been increasingly used for studying bacterial pathogenesis in vivo. These host models are amenable for...
Article
Full-text available
Microcin E492 is a pore-forming bacteriocin with toxic activity against Enterobacteriaceae, which undergoes amyloid aggregation as a mechanism to regulate its toxicity. To be active, it requires the posttranslational attachment to the C-terminus of a glycosylated enterochelin derivative (salmochelin), a process carried out by the proteins MceC, Mce...
Data
Fur does not regulate mceC expression. E. coli wt and Δfur cells were transformed with a reporter fusion between the last codon of mceC and lacZ (mceC’-‘lacZ), and growth in M9 medium. The optical density at 600 nm (A) and the β-galactosidase activity (B) were measured for each condition at different times and phases of growth (Early exponential, O...
Data
Effect of MceX overexpression on the LacZ activity of cells carrying a mceX’-‘lacZ fusion. E. coli cells carrying a plasmid harboring lacZ gene fused to the first codon of mceX were transformed with the compatible plasmid pT5-mceX, allowing the IPTG-inducible expression of mceX. LacZ activity was measured for cells growing in presence of 1 mM IPTG...
Article
Full-text available
Multiresistant and invasive hypervirulent Klebsiella pneumoniae strains have become one of the most urgent bacterial pathogen threats. Recent analyses revealed a high genomic plasticity of this species, harboring a variety of mobile genetic elements associated with virulent strains, encoding proteins of unknown function whose possible role in patho...
Article
Full-text available
Inorganic polyphosphate (polyP) deficiency in enteric bacterial pathogens reduces their ability to invade and establish systemic infections in different hosts. For instance, inactivation of the polyP kinase gene (ppk) encoding the enzyme responsible for polyP biosynthesis reduces invasiveness and intracellular survival of Salmonella enterica serova...
Data
Overrepresentation analysis for proteins found exclusively or enriched in amoebae infected with S. Typhimurium wild type or Δppk.
Data
Proteins found exclusively or enriched in a given experimental condition, classified according to COG categories.
Data
List of all proteins detected in uninfected amoebae, and in amoebae infected with S. Typhimurium wild type or Δppk, and their corresponding PANTHER annotation.
Article
Pathogenic Salmonella strains have a set of virulence factors allowing them to generate systemic infections and damage in a variety of hosts. Among these factors, bacterial proteins secreted by specialized systems are used to penetrate the host's intestinal mucosa, through the invasion and destruction of specialized epithelial M cells in the intest...
Article
Full-text available
The red yeast X. dendrorhous is one of the few natural sources of astaxanthin, a carotenoid used in aquaculture for salmonid fish pigmentation and in the cosmetic and pharmaceutical industries for its antioxidant properties. Genetic control of carotenogenesis is well characterized in this yeast; however, little is known about the regulation of the...
Article
Full-text available
Surrogate host models have been employed to study bacterial virulence mechanisms of important human pathogens. Particularly, zebrafish (Danio rerio) has been used to determine the role of vertebrate innate immunity during bacterial infections. The easy-to-obtain large number of embryos and optical transparency of larvae allow live cell imaging of t...
Preprint
Full-text available
Surrogate host models have been employed to study bacterial virulence mechanisms of important human pathogens. Particularly, zebrafish ( Danio rerio ) has been used to determine the role of vertebrate innate immunity during bacterial infections. The easy-to-obtain large number of embryos and optical transparency of larvae allow live cell imaging of...
Article
Full-text available
Due to the developing of multi-resistant and invasive hypervirulent strains, Klebsiella pneumoniae has become one of the most urgent bacterial pathogen threats in the last years. Genomic comparison of a growing number of sequenced isolates has allowed the identification of putative virulence factors, proposed to be acquirable mainly through horizon...
Article
Full-text available
Microcin E492 (MccE492) is a pore-forming bacteriocin produced and exported by Klebsiella pneumoniae RYC492. Besides its antibacterial activity, excreted MccE492 can form amyloid fibrils in vivo as well as in vitro. It has been proposed that bacterial amyloids can be functional playing a biological role, and in the particular case of MccE492 it wou...
Article
Full-text available
Microcin E492, a channel-forming bacteriocin with the ability to form amyloid fibers, is exported as a mixture of two forms: unmodified (inactive) and post-translationally modified at the C-terminus with a salmochelin-like molecule, which is an essential modification for conferring antibacterial activity. During the stationary phase, the unmodified...
Article
Full-text available
Here, we report the draft genome sequence of the Gram-negative strain Klebsiella pneumoniae RYC492, which produces the amyloid-forming and antibacterial peptide microcin E492. The sequenced genome consists of a 5,095,761-bp assembled open chromosome where the gene cluster for microcin production is located in a putative 31-kb genomic island flanked...
Article
Full-text available
The yeast Xanthophyllomyces dendrorhous is one of the most promising and economically attractive natural sources of astaxanthin. The biosynthesis of this valuable carotenoid is a complex process for which the regulatory mechanisms remain mostly unknown. Several studies have shown a strong correlation between the carbon source present in the medium...
Article
Xanthophyllomyces dendrorhous is a basidiomycetous yeast of considerable biotechnological interest because it synthesizes astaxanthin as its main carotenoid. The carotenoid production increases when it is grown using nonfermentable compounds as the sole carbon source. This work analyzes the expression of the carotenogenic genes and their relationsh...
Article
Full-text available
The yeast Xanthophyllomyces dendrorhous synthesizes astaxanthin, a carotenoid with high commercial interest. The proposed biosynthetic route in this organism is isopentenyl-pyrophosphate (IPP) --> geranyleranyl pyrophosphate (GGPP) --> phytoene --> lycopene --> beta-carotene --> astaxanthin. Recently, it has been published that the conversion of be...
Article
Full-text available
The cloning and nucleotide sequence of the genes (idi, crtE, crtYB, crtl and crtS) controlling the astaxanthin biosynthesis pathway of the wild-type ATCC 24230 strain of Xanthophyllomyces dendrorhous in their genomic and cDNA version were obtained. The idi, crtE, crtYB, crtl and crtS genes were cloned, as fragments of 10.9, 11.5, 15.8, 5.9 and 4 kb...

Questions

Questions (11)
Question
   
In the most general sense, a prion is a misfolded protein that can template the conformational change of a related (or the same) protein from a native-folded (soluble) form to the misfolded state. Hence, people says that a prion can exist in two states active/inactive or soluble/insoluble. Thinking in this definition, many amyloid-forming proteins may be considered as prions, since they also exists in two states (soluble/aggregated), and if you wait until amyloid fibers (inactive protein) form and then add those fibers to a mixture containing the soluble protein, the fibers (or their fragments) will act as seeds templating the conversion of the soluble protein into the amyloid form. So, should a protein be considered as a prion just by the fact that it can seed their own aggregation?
Question
We are looking for applying this technology in Klebsiella pneumoniae cells. Do any of you know any company who offer this kind of service for bacterial cells?. After searching in the internet, I only found the service available for eukaryotic cells.
Question
We are trying to use a gentamicin resistance cassette as a selectable marker in E. coli and Klebsiella. The cassette was PCR amplified from the CRIM plasmid pAH153 described originally by Haldimann and Wanner, and subcloned in another plasmid. The problem is that when we grow strains carrying pAH153 and the derivative mentioned above in gentamicin (10 ug/ml), cell growth is very variable, sometimes ranging from no growth or poor growth, to normal growth. Trying to find an explanation for such variation I found in the literature some evidence indicating that gentamicin activity is highly dependent on pH of the culture medium. So, the questions are if any of you have experimented similar issues with gentamicin selection in gram-negative bacteria, and if you use a medium with adjusted pH for doing so. Thanks
Question
We are measuring gene expression from cDNA samples prepared from bacterial RNA. Before cDNA synthesis, we treated RNA samples with DNAse to remove putative contaminating genomic DNA. However, when we use the non retrotranscribed RNA (treated with DNAse) as a template for qPCR, we obtain an amplification curve with a Ct value that falls in the same range of the Ct obtained using cDNA. We already checked the DNAse, and we saw that in the same conditions used for treating the RNA, the enzyme is capable of degrading several micrograms of a DNA sample (so the enzyme activity seems to be OK). Water controls (water instead of RNA or cDNA template) didn`t amplify, so we discarded contamination of tubes, tips, primers and qPCR kit. Have anyone encountered problems like this? If so, can you tell me possible causes?
Question
People often says that plasmids become unstable if you use them to clone long DNA fragments (over 20 kb), and that for this purpose is better to use cosmids (can carry DNA fragments up to 50 kb). However, as far as I know the only difference between both vectors is the presence of cos sites in the latter, and that those cos sites are important for DNA packaging into viral particles (not involved in vector replication). Considering that, how can we explain that cosmids remain stable with larger DNA segments?. To bring up an example, pHC79 is a cosmid derived from pBR322 plasmid (they are exactly the same except for the presence of lambda cos sites). pHC79 has been successfully used to clone DNA segments up to 50 kb. The question is: Can we expect that pBR322 works as well as pHC79?
Question
I'm interested in using the Bochner-Maloy Tetracycline-sensitivity positive selection strategy, described many years ago (works with different enterobacteriaceae). In this method, culture medium must be supplemented with about 6 ml/L of a Fusaric acid stock solution (2 mg/ml). Do anyone know in which solvent this stock solution should be prepared? For how much time can the stock solution be stored? At which temperature?