epsABCJ genes are involved in the biosynthesis of the exopolysaccharide mauran produced by Halomonas maura

• Published in: Microbiology (Society for General Microbiology) Vol. 151; no. 9; pp. 2841 - 2851
• Main Authors: Arco, Yolanda, Llamas, Inmaculada, Martinez-Checa, Fernando, Argandona, Montserrat, Quesada, Emilia, Moral, Ana del
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.09.2005; Society for General Microbiology
• Subjects: Amino Acid Sequence; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biotechnology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Genetic engineering; Genetic technics; Genetics; Halomonas - cytology; Halomonas - genetics; Halomonas - metabolism; Halomonas maura; Methods. Procedures. Technologies; Microbiology; Molecular cloning; Molecular Sequence Data; Multigene Family - physiology; Polysaccharides, Bacterial - biosynthesis; Polysaccharides, Bacterial - chemistry; Polymerase chain reaction; Halomonas; Gene; Transposon; Sequence alignment; Bacteria; Biosynthesis; Electron microscopy; Polysaccharide; Halomonadaceae; Sea
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.27981-0

Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain Correspondence Ana del Moral admoral{at}ugr.es The moderately halophilic strain Halomonas maura S-30 produces a high-molecular-mass acidic polymer (4·7 x 10 6  Da) composed of repeating units of mannose, galactose, glucose and glucuronic acid. This exopolysaccharide (EPS), known as mauran, has interesting functional properties that make it suitable for use in many industrial fields. Analysis of the flanking regions of a mini-Tn 5 insertion site in an EPS-deficient mutant of H. maura , strain TK71, led to the identification of five ORFs ( epsABCDJ ), which form part of a gene cluster ( eps ) with the same structural organization as others involved in the biosynthesis of group 1 capsules and some EPSs. Conserved genetic features were found such as JUMPstart and ops elements, which are characteristically located preceding the gene clusters for bacterial polysaccharides. On the basis of their amino-acid-sequence homologies, their putative hydropathy profiles and the effect of their mutations, it is predicted that EpsA (an exporter-protein homologue belonging to the OMA family) and EpsC (a chain-length-regulator homologue belonging to the PCP family) play a role in the assembly, polymerization and translocation of mauran. The possibility that mauran might be synthesized via a Wzy-like biosynthesis system, just as it is for many other polysaccharides, is also discussed. This hypothesis is supported by the fact that EpsJ is homologous with some members of the PST-exporter-protein family, which seems to function together with each OMA–PCP pair in polysaccharide transport in Gram-negative bacteria, transferring the assembled lipid-linked repeating units from the cytoplasmic membrane to the periplasmic space. Maximum induction of the eps genes is reached during stationary phase in the presence of 5 % (w/v) marine salts. Abbreviations: EPS, extracellular polysaccharide or exopolysaccharide The GenBank/EMBL/DDBJ accession number for the sequence reported in this paper is AY918062 . HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS INT J SYST EVOL MICROBIOL MICROBIOLOGY J GEN VIROL J MED MICROBIOL ALL SGM JOURNALS Copyright © 2005 Society for General Microbiology.