Investigation on the linkage units between cell surface substances

点击翻译按钮获取中文摘要

In this project, the structure and role of linkage units between the cell surface substances were investigated. As far as we have studied, teichoic acid chains with rather simple backbone repeating units, such as glycerol teichoic acid, ribitol teichoic acid, poly(GlcNAc-1-P), and poly(galactosyl-glycerol phosphate), seem to be linked to peptidoglycan through special linkage units, irrespective of their structural diversity in the backbone chains and glycosidic branches. Each of the linkage units consists of a linkage sugar part and an outer part containing one or more glycerol phosphate residues. The presence of two types of the linkage sugar parts is shown, namely the ManNAc-GlcNAc (or ManNAc-GlcN) type in a wide variety of bacteria and the Glc-GlcNAc type in a limited number of bacteria. On the other hand, the structures of the outer parts are divesified depending on the bacterial species: Gro-P, in L. plantarum; <(Gro-P)_2> , in B. subtilis; <(Gro-P)_3> , in S. aureus and B. coagul … More ans; <(Gro-P)_7> , in B. pumilus; Glc-Glc-Gro-P, in Listeria. The glycerol phosphate part is expected to provide a valuable markers in phylogenetic classification of gram-positive bacteria.In contrast to above teichoic acids, almost all of teichuronic acids and a minor teichoic acid (in B. coagulans) with complex backbone repeating units are shown to be directly linked to peptidoglycan without any special linkage unit. The types of junction of wall polymers to peptidoglycan seem to be essentially related to the modes of biosynthesis of the polymer chains. The de novo biosynthesis of tiechoic acid chains is shown to proceed through the prior formation of linkage-unit-bound lipid intermediates in the membrane systems of S. aureus, B. subtilis, B. coagulans, and other bacteria. On the other hand, the biosynthesis of teichuronic acids and wall neutral polysaccharides is shown to proceed through the formation of repeating-unit-bound lipid intermediates. The results of this project seem to be valuable for understanding the assembly of cell surface substances. Less