A membrane-associated lipomannan in micrococci

Abstract

Membranes of Micrococcus lysodeikticus, Micrococcus flavus and Micrococcus sodonensis contain acidic lipomannans. Lipoteichoic acids could not be detected in these organisms, and the suggestion that they are substituted for by the lipomannans is strengthened by the chemical and physical resemblances between the two polymers. The mannans contain glycerol, ester-linked fatty acids and mono-esterified succinic acid residues, giving them both hydrophobic and charged properties. The M. lysodeikticus mannan has a chain of about 60 hexose units with two branch points, and is joined at its reducing end to the 1-position of a glycerol moiety bearing two fatty acid residues. Succinic acid on the mannan enables it to bind Mg2+ efficiently, and the polymer is firmly associated with the cytoplasmic membrane, probably by intercalation of its fatty acids with those of the membrane lipids.