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Martin J.-F.,University of León | Garcia-Estrada C.,Institute of Biotechnology of Leon | Ullan R.V.,Institute of Biotechnology of Leon
Biomolecular Concepts | Year: 2013

Peroxisomes are ubiquitous organelles that enclose catalases, fatty acid-oxidizing enzymes, and a variety of proteins involved in different cellular processes. Interestingly, the late enzymes involved in penicillin biosynthesis, and the isopenicillin N epimerization enzymes involved in cephalosporin biosynthesis are located inside peroxisomes in the producer fungi Penicillium chrysogenum and Acremonium chrysogenum. Peroxisome proteins are targeted to those organelles by peroxisomal targeting signals located at the C-terminus (PTS1) or near the N-terminal end (PTS2) of those proteins. Peroxisomal membrane proteins (PMPs) are largely recruited by the interaction with specific sequences in the Pex19 protein. The compartmentalization into peroxisomes of several steps of the biosynthesis of penicillin, cephalosporin, and other secondary metabolites raises the question of how the precursors and/or intermediates of the biosynthesis of β-lactam antibiotics are transported into peroxisomes and the mechanisms of secretion of the final products (penicillin or cephalosporin) from peroxisomes to the extracellular medium. Recent advances in peroxisome proteomics, immunoelectron microscopy, and fluorescence labeling have shown that the transport of these intermediates is mediated by membrane proteins of the major facilitator superfamily class (drug/H + antiporters) containing 12 transmembrane-spanning domains (TMS). In some cases, the transport of the substrates (e.g., fatty acids) or intermediates may be mediated by ATP-binding cassette (ABC) transporters. Knowledge on the transport and secretion mechanisms is of paramount importance to understand the complex mechanisms of cell differentiation and their crosstalk with the biosynthesis of different secondary metabolites that act as biochemical signals between the producer cells and also as communication signals with competing microorganisms (e.g., antimicrobial agents or plant elicitors). © 2013 by Walter de Gruyter Berlin Boston.


Prieto C.,Institute of Biotechnology of Leon | Garcia-estrada C.,Institute of Biotechnology of Leon | Lorenzana D.,Institute of Biotechnology of Leon | Martin J.F.,Institute of Biotechnology of Leon
Bioinformatics | Year: 2012

Non-ribosomal peptide synthetases (NRPSs) are multi-modular enzymes, which biosynthesize many important peptide compounds produced by bacteria and fungi. Some studies have revealed that an individual domain within the NRPSs shows significant substrate selectivity. The discovery and characterization of non-ribosomal peptides are of great interest for the biotechnological industries. We have applied computational mining methods in order to build a database of NRPSs modules that bind to specific substrates. We have used this database to build a hidden Markov model predictor of substrates that bind to a given NRPS. © The Author 2011. Published by Oxford University Press. All rights reserved.


Craig M.,University of Liège | Lambert S.,University of Liège | Jourdan S.,University of Liège | Tenconi E.,University of Liège | And 6 more authors.
Environmental Microbiology Reports | Year: 2012

Iron is one of the most abundant elements on earth but is found in poorly soluble forms hardly accessible to microorganisms. To subsist, they have developed iron-chelating molecules called siderophores that capture this element in the environment and the resulting complexes are internalized by specific uptake systems. While biosynthesis of siderophores in many bacteria is regulated by iron availability and oxidative stress, we describe here a new type of regulation of siderophore production. We show that in Streptomyces coelicolor, their production is also controlled by N-acetylglucosamine (GlcNAc) via the direct transcriptional repression of the iron utilization repressor dmdR1 by DasR, the GlcNAc utilization regulator. This regulatory nutrient-metal relationship is conserved among streptomycetes, which indicates that the link between GlcNAc utilization and iron uptake repression, however unsuspected, is the consequence of a successful evolutionary process. We describe here the molecular basis of a novel inhibitory mechanism of siderophore production that is independent of iron availability. We speculate that the regulatory connection between GlcNAc and siderophores might be associated with the competition for iron between streptomycetes and their fungal soil competitors, whose cell walls are built from the GlcNAc-containing polymer chitin. Alternatively, GlcNAc could emanate from streptomycetes' own peptidoglycan that goes through intense remodelling throughout their life cycle, thereby modulating the iron supply according to specific needs at different stages of their developmental programme. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.


PubMed | Institute of Biotechnology of Leon
Type: Journal Article | Journal: Microbial biotechnology | Year: 2011

Penicillins and cephalosporins are -lactam antibiotics widely used in human medicine. The biosynthesis of these compounds starts by the condensation of the amino acids L--aminoadipic acid, L-cysteine and L-valine to form the tripeptide -L--aminoadipyl-l-cysteinyl-D-valine catalysed by the non-ribosomal peptide ACV synthetase. Subsequently, this tripeptide is cyclized to isopenicillin N that in Penicillium is converted to hydrophobic penicillins, e.g. benzylpenicillin. In Acremonium and in streptomycetes, isopenicillin N is later isomerized to penicillin N and finally converted to cephalosporin. Expression of genes of the penicillin (pcbAB, pcbC, pendDE) and cephalosporin clusters (pcbAB, pcbC, cefD1, cefD2, cefEF, cefG) is controlled by pleitropic regulators including LaeA, a methylase involved in heterochromatin rearrangement. The enzymes catalysing the last two steps of penicillin biosynthesis (phenylacetyl-CoA ligase and isopenicillin N acyltransferase) are located in microbodies, as shown by immunoelectron microscopy and microbodies proteome analyses. Similarly, the Acremonium two-component CefD1-CefD2 epimerization system is also located in microbodies. This compartmentalization implies intracellular transport of isopenicillin N (in the penicillin pathway) or isopenicillin N and penicillin N in the cephalosporin route. Two transporters of the MFS family cefT and cefM are involved in transport of intermediates and/or secretion of cephalosporins. However, there is no known transporter of benzylpenicillin despite its large production in industrial strains.


PubMed | Institute of Biotechnology of Leon
Type: Journal Article | Journal: The Biochemical journal | Year: 2010

The mechanisms of compartmentalization of intermediates and secretion of penicillins and cephalosporins in -lactam antibiotic-producing fungi are of great interest. In Acremonium chrysogenum, there is a compartmentalization of the central steps of the CPC (cephalosporin C) biosynthetic pathway. In the present study, we found in the early CPC cluster a new gene named cefP encoding a putative transmembrane protein containing 11 transmembrane spanner. Targeted inactivation of cefP by gene replacement showed that it is essential for CPC biosynthesis. The disrupted mutant is unable to synthesize cephalosporins and secretes a significant amount of IPN (isopenicillin N), indicating that the mutant is blocked in the conversion of IPN into PenN (penicillin N). The production of cephalosporin in the disrupted mutant was restored by transformation with both cefP and cefR (a regulatory gene located upstream of cefP), but not with cefP alone. Fluorescence microscopy studies with an EGFP (enhanced green fluorescent protein)-SKL (Ser-Lys-Leu) protein (a peroxisomal-targeted marker) as a control showed that the red-fluorescence-labelled CefP protein co-localized in the peroxisomes with the control peroxisomal protein. In summary, CefP is a peroxisomal membrane protein probably involved in the import of IPN into the peroxisomes where it is converted into PenN by the two-component CefD1/CefD2 protein system.

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