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

verfasst von
Anke Becker, Helge Küster, Karsten Niehaus, Alfred Pühler
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 β-(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.

Externe Organisation(en)
Universität Bielefeld
Typ
Artikel
Journal
MGG Molecular & General Genetics
Band
249
Seiten
487-497
Anzahl der Seiten
11
ISSN
0026-8925
Publikationsdatum
01.09.1995
Publikationsstatus
Veröffentlicht
Peer-reviewed
Ja
ASJC Scopus Sachgebiete
Genetik
Elektronische Version(en)
https://doi.org/10.1007/BF00290574 (Zugang: Unbekannt)