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PMID: 8544814 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Extension of the Rhizobium meliloti succinoglycan biosynthesis gene cluster: identification of the exsA gene encoding an ABC transporter protein, and the exsB gene which probably codes for a regulator of succinoglycan biosynthesis.

Molecular & general genetics : MGG ·Vol. 249 ·No. 5 ·1995-12-15 ·Pages 487-97

Becker A, Küster H, Niehaus K, Pühler A

Abstract

Two new genes, designated exsA and exsB, were identified adjacent to the 24 kb exo gene cluster of Rhizobium meliloti, which is involved in succinoglycan (EPS I) biosynthesis. The derived amino acid sequence of ExsA displayed significant homologies to ATP binding cassette (ABC) transporter proteins. R. meliloti strains mutated in exsA were characterized by a decreased ratio of HMW to LMW EPS I, indicating a function for ExsA in EPS I biosynthesis. The R. meliloti NdvA protein, which is involved in the transport of cyclic beta-(1,2)-glucans, was identified as the closest homologue of ExsA. R. meliloti exsB mutants produced a three-fold increased amount of EPS I in comparison to the wild-type strain. In contrast, high copy number of exsB resulted in a decrease in the EPS I level to 20% of wild type, indicating that the exsB gene product can negatively influence EPS I biosynthesis. It was demonstrated that this influence is not due to transcriptional regulation of the exo genes by the exsB gene product. By plasmid integration it was shown that exsA and exsB represent monocistronic transcription units.

MeSH Terms
ATP-Binding Cassette Transporters/chemistry,genetics Amino Acid Sequence Bacterial Proteins/genetics Base Sequence DNA, Bacterial DNA-Binding Proteins/chemistry,genetics Gene Expression Regulation, Bacterial Genes, Bacterial Genes, Regulator Lipoproteins/genetics Molecular Sequence Data Multigene Family Mutation Open Reading Frames Polysaccharides, Bacterial/biosynthesis,genetics Sequence Analysis Sequence Homology, Amino Acid Sinorhizobium meliloti/genetics Trans-Activators/chemistry,genetics Transcription, Genetic
Chemicals
ATP-Binding Cassette Transporters Bacterial Proteins DNA, Bacterial DNA-Binding Proteins ExsA protein, bacteria ExsB protein, Pseudomonas aeruginosa Lipoproteins Polysaccharides, Bacterial Trans-Activators succinoglycan
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Becker A
Lehrstuhl für Genetik, Fakultät für Biologie, Universität Bielefeld, Federal Republic of Germany.
Küster H
Niehaus K
Pühler A
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Article Info
Journal
Molecular & general genetics : MGG
Abbr.
Mol Gen Genet
ISSN
0026-8925
DOI
10.1007/BF00290574
Published
1995-12-15
Pages
487-97
Language
English
Region
Germany
NLM ID
0125036
Subset
IM
Databases
GENBANK
Z50189
External Links
PubMed source DOI: 10.1007/BF00290574
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