GENETIC-ANALYSIS OF MECILLINAM-RESISTANT MUTANTS OF CAULOBACTER-CRESCENTUS DEFICIENT IN STALK BIOSYNTHESIS

Stalk synthesis in Caulobacter crescentus is a developmentally control led and spatially restricted event that requires the synthesis of pept idoglycan at the stalk-cell body junction. We show that the p-lactam a ntibiotic mecillinam prevents stalk synthesis by inhibiting stalk elon gation. In addition, mecillinam causes an increase in the diameter of the stalk at the stalk-cell body junction. We describe two mutations t hat confer resistance to mecillinam and that prevent stalk elongation. These mutations are probably allelic, and they map to a locus previou sly not associated with stalk synthesis.