Patchiness of murein insertion into the sidewall of Escherichia coli

1 Centro de Biologia Molecular ‘Severo Ochoa’, Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, Facultad de Ciencias, 28049 Madrid, Spain 2 Max-Planck-Institut für Entwicklungsbiologie, 72076 Tübingen, Germany 3 Biology Department, Indiana University, Bloomington, IN 47405-6801, USA Correspondence Arthur L. Koch Koch{at}Indiana.edu This paper extends, with computer techniques, the authors' previous work on the kinetics of pole wall and sidewall synthesis in Escherichia coli . These findings extend the conclusion that the nascent poles are made of entirely new material and that no new material is inserted into old poles. This requires re-evaluation of ideas in the literature about wall growth and cell division. Mechanisms of various types have been suggested for the growth of Gram-negative rod-shaped bacteria and these will also require major re-evaluation because of the finding, reported here, that the sidewall is made in several modes: patches of new murein, bands of new material largely going circumferentially around the cell, and areas of the sidewall that are enlarged by an intimate and regular admixture of new with the old muropeptides.