Structure des parois de Bacillus megaterium KM II. étude des complexes mucopeptidique et phosphomucopolysaccharidique

Bacillus megaterium KM cell walls are composed of two distinct heteropolymers. The first, referred as to X-teichoic acid, presents a molecular weight of about 11000. It consists of about 10 subunits containing P, glucose and GlcNHAc in the molar ratio 1/2/1.3 as well as a polyol compound. It does not play any role in maintaining the rigidity of the wall. The second can be visualized as a three-dimensional network of structural subunits consisting of four mucopeptide residues with an average composition GlcNHAc1- (N-acetylmuramic acid)1-Ala2.20-Glu1- ([alpha],[epsilon]-diaminopimelic acid)1. They also contain glucose. This mucopeptide is the basal structure of the wall. The two heteropolymers are present in equimolar proportions. They are covalently bound through glucosido-muraminyl bridges branched on some of the alanine residues of the basal mucopeptide thanks to amidic linkages.