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The Myxococcus xanthus rfbABC operon encodes an ATP-binding cassette transporter homolog required for O-antigen biosynthesis and multicellular development.

Authors
  • Guo, D1
  • Bowden, M G
  • Pershad, R
  • Kaplan, H B
  • 1 Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston 77030, USA.
Type
Published Article
Journal
Journal of bacteriology
Publication Date
Mar 01, 1996
Volume
178
Issue
6
Pages
1631–1639
Identifiers
PMID: 8626291
Source
Medline
License
Unknown

Abstract

A wild-type sasA locus is critical for Myxococcus xanthus multicellular development. Mutations in the sasA locus cause defective fruiting body formation, reduce sporulation, and restore developmental expression of the early A-signal-dependent gene 4521 in the absence of A signal. The wild-type sasA locus has been located on a 14-kb cloned fragment of the M. xanthus chromosome. The nucleotide sequence of a 7-kb region containing the complete sasA locus was determined. Three open reading frames encoded by the genes, designated rfbA, B and C were identified. The deduced amino acid sequences of rfbA and rfbB show identity to the integral membrane domains and ATPase domains, respectively, of the ATP-binding cassette (ABC) transporter family. The highest identities are to a set of predicted ABC transporters required for the biosynthesis of lipopolysaccharide O-antigen in certain gram-negative bacteria. The rfbC gene encodes a predicted protein of 1,276 amino acids. This predicted protein contains a region of 358 amino acids that is 33.8% identical to the Yersinia enterocolitica O3 rfbH gene product, which is also required for O-antigen biosynthesis. Immunoblot analysis revealed that the sasA1 mutant, which was found to encode a nonsense codon in the beginning of rfbA, produced less O-antigen than sasA+ strains. These data indicate that the sasA locus is required for the biosynthesis of O-antigen and, when mutated, results in A-signal-independent expression of 4521.

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