The physiology of teichoic acid deficient staphylococci

Abstract

Cell walls isolated from a teichoic acid deficient mutant (52A5) of Staphylococcus aureus strain H were found to have lower capacities to bind cations than did walls of the parent strain. Both types of walls had higher binding affinities for Mg2+ and Ca2+ than for K+ and Na+. The reduced number of phosphate groups in 52A5 walls was reflected in a higher apparent pKa of 4.3 for displacement of Mg2+ (or Ca2+) during acid titration with HCl. The comparable pKa value for displacement of bound Mg2+ from parent-strain walls was 3.7. The reduced capacity of 52A5 walls to bind cations was not reflected in any significant increase in sensitivity to the growth inhibitory actions of ethylenediaminetetraacetate, low pH, or high NaCl concentrations. However, the 52A5 strain was somewhat more sensitive to the inhibitory effects of high pH. Also, mutant walls were found to be structurally more compact than walls of the parent strain, presumably because of less extensive electrostatic repulsion within the wall matrix.