S. Swart et al., SEVERAL PHENOTYPIC CHANGES IN THE CELL-ENVELOPE OF AGROBACTERIUM-TUMEFACIENS CHVB MUTANTS ARE PREVENTED BY CALCIUM LIMITATION, Archives of microbiology, 161(4), 1994, pp. 310-315
The chvB gene of Agrobacterium tumefaciens encodes a 235 kDa proteinac
eous intermediate involved in the synthesis of beta-1,2-glucan. chvB m
utants show a pleiotropic phenotype. Besides not to produce cyclic bet
a-1,2-glucan, chvB mutants have been reported to be avirulent, attachm
ent-deficient, and nonmotile. In this study we report additional diffe
rences from the parent strain, probably all linked to changes in the c
ell envelope. This pleiotropic phenotype - except for attachment and v
irulence - could largely be prevented by growing chvB cells with low l
evels of calcium. Although a role for beta-1,2-glucan in osmoadaptatio
n has been proposed, the mode of action of beta-1,2-glucan is not know
n. We speculate that in A. tumefaciens beta-1,2-glucan stabilizes memb
ranes, which would be important especially in hypotonic media containi
ng calcium.