Studies on the Chemical Structure of the Streptococcal Cell Wall

Abstract

Recent studies on the chemical composition of the bacterial cell wall indicate that the basic structural component, which is responsible for the rigidity of the wall, is similar in all bacteria examined (1). This component, designated as the cell wall mucopeptide, is composed of N-acetylglucosamine, N-acetylmuramic acid (3-O-lactyl-N-acetylglucosamine), and a limited number of amino acids. In the case of streptococci these two amino sugars and alanine, lysine, glycine, and glutamic acid have been identified in hydrolysates of trypsinized cell walls. However, this analysis of hydrolysates does not provide information on the arrangement of these substances in the chemical structure of the cell wall. The data reported here indicate that the two amino sugars and the four amino acids do in fact comprise a mucopeptide fraction. This substance is distinct from the other major cell wall component, the group-specific carbohydrate hapten, which contains rhamnose and N-acetylglucosamine.The work of Salton (2) has shown that the lysis of certain bacteria by lysozyme is accompanied by the release of the cell wall mucopeptide into soluble fragments. Lysis of streptococcal cell wall by phage-associated lysin is shown to be associated with a similar release of fragments of mucopeptide. These findings support the growing evidence which suggests that the specific linkage split by lysozyme and other cell wall-dissolving enzymes resides in the mucopeptide fraction.Materials and Methods Streptococcal Strains.--Group A streptococcal strains T12, D58, and $43/100, and Group A-variant strains T27A and K43 var. were used to prepare cell walls.Preparation of Call Wal/s.--The cell wails were prepared by the method of Salton and Home which employs a Mickle disintegrator (3). Differential centrifugation was used to separate the cell walls from the fine particulate material; and the walls were then treated with trypsin in phosphate-buffered saline, dialyzed against water, and finally lyophilized.

Variation in the Group-Specific Carbohydrate of Group C Hemolytic Streptococci

“…Both carbohydrates contain rhamnose but that of Group A contains N-acetylglucosamine while that of Group C contains N-acetylgalactosamine (1). The specific carbohydrate of an antigenic variant of Group A streptococci, designated A-variant, is composed primarily of rhamnose (4). The work of McCarty (2) with induced enzymes from soil organisms has identified the principle determinants of specificity in the Groups A and A-variant carbohydrates.…”

“…The methods for preparing cell wails and the isolation of the group-specific carbohydrates have been previously described (4). In these studies all of the carbohydrate preparations were extracted by Fuller's formamide procedure (5).…”

“…Analytical Mahods.--Analyses for rhamnose, glucosamine, and galactosamine were performed by previously described methods (4).…”

The Bacterial Induction of Homograft Sensitivity

“…The inability of Group C streptococci to induce homograft sensitivity militates against this possibility. When coupled with other studies of streptococci (14)(15)(16)(17) it may also provide a guide to the localization of the factor(s) in Group A streptococci responsible for the induction of homograft sensitivity. Reports of the immunologic identity of Group A and Group C cell walls (with the exception of a single amino-sugar determinant) by Krause and McCarty (14,15) and Araujo and Krause (16), and Freimer's (17) demonstration of immunological differences between Group A and Group C cytoplasmic membranes, may be of particular relevance to this question.…”

New Approaches for the Laboratory Recognition of M Types of Group a Streptococci

“…Streptococcal Group-Specific Carbohydrate.--The preparation of Group A carbohydrate was previously described (8).…”