Autoradiographic analysis of diaminopimelic acid incorporation in filamentous cells of Escherichia coli: repression of peptidoglycan synthesis around the nucleoid

Abstract

Peptidoglycan synthesis rate in nonconstricting filaments of Escherichia coli dnaX(Ts) has been studied by autoradiography of incorporated [3H]diaminopimelic acid. Analysis of autoradiograms of whole cells and sacculi showed that peptidoglycan is synthesized at a reduced rate in the nucleoid-containing parts of these filaments. The lower rate of peptidoglycan synthesis in the cell center coincides with a higher local rate of protein synthesis. DNA-less cell formation in dnaX(Ts), dnaX(Ts) sfiA, and the minB minicell-forming mutant is accompanied by a local increase in peptidoglycan synthesis at the constriction site.