The Lysis of Group a Hemolytic Streptococci by Extracellular Enzymes of Streptomyces Albus

Abstract

In the preceding paper (1) evidence is presented for the view that lysis of group A streptococci by filtrates of Streptomyces albus is initiated by a nonproteolytic enzyme of undetermined nature. The potent proetolytic enzyme present in the filtrates is by itself incapable of dissolvingstreptococci and it appears to play a secondary role in lysis. The present investigation is concerned with the identity of the substrate in the streptococcal cell which is attacked by the non-proteolytic enzyme in the first stages of lysis. Identification of this substrate should not only provide an indication of the type of enzyme involved but in addition should lead to a better understanding of the structure of the streptococcal cell.The experiments herein described indicate that the bacterial cell wall is the structure attacked in enzymatic lysis of streptococci. Studies on the chemical composition of the streptococcal cell wall are presented, and the data are related to previously known facts concerning the serological constituents of group A streptococci. Materials and MethodsGroup A Streptococci.--Group A strains of several serological types were employed. The organisms were grown in Todd-Hewitt broth, collected by centrifugation and washed three times with 0.85 per cent sodium chloride. The washed cells were treated with several volumes of acetone, washed with acetone and finally dried in vacuo.Streptomyces albus Enzyme Preparations.--The concentrates of the lytic enzymes were prepared by the methods described in the preceding paper (1).Analytical Methods.--Total nitrogen was determined by the direct nesslerizafion microKjeldahl procedure of Koch and McMeekin (2). Total phosphorus determinations were made by the method of Allen (3). Quantitative hexosamine analyses were made by a modification (4) of the Elson and Morgan procedure (5) after hydrolysis with 2 N HCI at 100°C. in sealed ampoules. Reducing sugars were determined after hydrolysis by the Hanes modification (6) of the Hagedorn-Jensen method. Methylpentose was determined without prior hydrolysis of the sample by the eysteine sulfuric acid method of Dische and Shetties (7). 569

Immunochemical Studies on the Specific Carbohydrate of Group G Streptococci

“…Rhamnose has been identified as a major component of the carbohydrates of Groups A, A-variant, C-variant, and C streptococci (2,3,9,13), and the present findings indicate Group G is similar to the others in this respect. In the variant carbohydrates rhamnose ollgosaccharides have been identified as the major determinant of antigenic specificity but in the case of Groups A and C this sugar has relatively little antigenic significance (2).…”

GacA is essential for Group A Streptococcus and defines a new class of monomeric dTDP‐4‐dehydrorhamnose reductases (RmlD)

“…Teichoic or teichuronic acids are typical and well‐studied SCWP in Gram‐positive bacteria and play an important role in normal cell function and infection (Weidenmaier and Peschel, 2008). Many β‐hemolytic streptococcal species appear to lack expression of typical teichoic or teichuronic acid structures (Sutcliffe et al ., 2008; Caliot et al ., 2012) and instead express a rhamnose‐rich polymer, which comprises approximately half of the cell wall mass (McCarty, 1952). Historically, expression of these evolutionary conserved glycans underlies classification of β‐hemolytic streptococci in Lancefield groups (A, B, C, G …) (Lancefield, 1933), a feature that is still applied in contemporary rapid test kits to diagnose streptococcal infections.…”

The Cell Walls of Group D Streptococci

“…Chloroform was used as a preservative. The resulting lysate was deproteinized by the method of McCarty (10), and the water-soluble carbohydrate purified as in the formamide procedure.…”