Role a Agrobacterium tumefaciens ChvA protein in export of. beta. -1,2-glucan
- Univ. of Washington, Seattle (USA)
Functional chvA and chvB genes are required for attachment of Agrobacterium tumefaciens to plant cells, an early step in crown gall tumor formation. Strains defective in these loci do not secrete normal amounts of cyclic {beta}-1,2-glucan. Whereas chvB is required for {beta}-1,2-glucan synthesis, the role of chvA in glucan synthesis or export has not been clearly defined. We found that cultures of chvA mutants contained as much neutral {beta}-1,2-glucan in the cell pellets as did the wild type, with no detectable accumulation of glucan in the culture supernatant. The cytoplasm of chvA mutant cells contained over three times more soluble {beta}-1,2-glucan than did the cytoplasm of the wild-type parent. Unlike the wild type, chvA mutants contained no detectable periplasmic glucan. The amino acid sequence of chvA is highly homologous to the sequences of bacterial and eucaryotic export proteins, as observed previously in the case of ndvA, a rhizobial homolog of chvA. Strong sequence homology within this family of export proteins is concentrated in the carboxy-terminal portions of the proteins, but placement of consensus ATP-binding sites, internal signal sequences, and hydrophobic domains are conserved over their entire lengths. These data suggest a model for {beta}-1,2-glucan synthesis in A. tumefaciens in which glucan is synthesized inside the inner membrane with the participation of ChvB and transported across the inner membrane with the participation of ChvA.
- DOE Contract Number:
- FG06-86ER13532
- OSTI ID:
- 7019011
- Journal Information:
- Journal of Bacteriology; (USA), Journal Name: Journal of Bacteriology; (USA) Vol. 41:3; ISSN JOBAA; ISSN 0021-9193
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ADHESION
AMINO ACID SEQUENCE
BACTERIA
BIOLOGICAL FUNCTIONS
CELL CONSTITUENTS
CELL MEMBRANES
CYTOPLASM
FUNCTIONS
GENES
MATHEMATICAL MODELS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
MICROORGANISMS
MOLECULAR STRUCTURE
MUTANTS
ORGANIC COMPOUNDS
PATHOGENS
PLANT CELLS
PROTEINS