The gtaB Marker in Bacillus subtilis 168 Is Associated with a Deficiency in UDPglucose Pyrophosphorylase

Abstract

Fifty-six mutants of Bacillus subtilis 168 were selected for resistance to bacteriophages .vphi. 29 or .vphi. 25. The mutations were all linked to previously described teichoic acid markers gtaA, gtaB or gtaC, for the first and last of which, the gene products have previously been identified. Each linkage group was shown to have two distinct phenotypes with respect to phage resistance and cell-wall galactosamine content. Recombination indexes of 0.35, 0.13 and 0.41 for groups A, B and C respectively were consistent with the presence of two average-sized genes in groups A and C. Correlation between genetic and phenotypic differences supported this conclusion and led to the designation of two new markers, gtaD and gtaE. Two- and three-factors transformation crosses suggested the order hisA-gtaB-gtaD-gtaA-tag-1 and gtaC-gtaE-argC. Assays for UDPglucose pyrophosphorylase and phosphoglucomutase activities in soluble extracts of representative mutants revealed that, in contrast to previous findings, the former activity was virtually undetectable in all nine group B mutants examined, suggesting that gtaB is the structural gene of this enzyme. Our results allow us to account for discrepancies with respect to previous reports. The thermosensitive mutation previously designated rodC1 was shown to be 90% cotransformable with tag-1. In view of their extremely similar phenotypes the former mutation was renamed tag-3, and the likely order obtained was gtaA-tag-3-tag-1. This suggests that many mutations associated with deformation of cell shape in B. subtilis are located in the region where teichoic acid genes map.