Isolation and Characterization of a New Extracellular Bacteriolytic Endopeptidase of <Emphasis Type="Italic">Lysobacter</Emphasis> sp. XL1

The previously unstudied bacteriolytic enzyme L(4) was isolated from the culture liquid of the bacterium Lysobacter sp. XL1 in electrophoretically homogeneous state. The enzyme L(4) is a diaminopimelinoyl-alanine endopeptidase relative to peptidoglycan of Lysobacter sp. XL1. The enzyme is an alkaline protein of approximately 21 kD. The N-terminal amino acid sequence of the enzyme has been determined - A V V N G V N Y V Gx T T A ... The maximal activity of the enzyme was observed in 0.05 M Tris-HCl at pH 8.0 and 50-55 degrees C. The half-inactivation temperature of the enzyme is 52 degrees C. The endopeptidase L(4) is not a metalloenzyme since it is not affected by EDTA. The enzyme is inhibited by p-chloromercuribenzoic acid by 72% and by phenylmethylsulfonyl fluoride by 43%, which indicates the involvement of serine and thiol groups in its functioning.     

The Effect of the Extracellular Bacteriolytic Enzymes of Lysobacter sp. on Gram-Negative Bacteria

The effect of the extracellular bacteriolytic enzymes of Lysobacter sp. on gram-negative bacteria was studied. These enzymes were found to be able to hydrolyze the peptidoglycan that was isolated from the gram-negative bacteria, the hydrolysis being completely inhibited by the cell wall lipopolysaccharide of these bacteria. The native cells of the gram-negative bacteria became susceptible to the bacteriolytic enzymes after the permeability of the outer membrane of the cells was altered by treating them with polymyxin B.     

Extracellular yeast-lytic enzyme of the bacterium <Emphasis Type="Italic">Lysobacter</Emphasis> sp. XL 1

An enzyme exhibiting yeast-lytic activity has been isolated from the culture liquid of the bacterium Lysobacter sp. XL 1. The optimal conditions for the hydrolysis of Saccharomyces cerevisiae cells by the enzyme have been established: 0.15 M sodium acetate buffer, pH 6.0, 50 degrees C. The yeast-lytic activity of the enzyme is inhibited by EDTA, p-chloromercuribenzoate, and phenylmethylsulfonyl fluoride. According to the data of SDS-PAGE, the molecular weight of the protein is 36 kD. The enzyme hydrolyzes casein, hemoglobin, and synthetic peptide Abz-Ala-Ala-Phe-pNA, i.e. it exhibits proteolytic activity. The properties of the enzyme and its molecular weight correspond to those of a previously isolated extracellular metalloproteinase. The N-terminal amino acid sequence of the protein exhibits 67% homology with the N-terminal sequence of achromolysine of Achromobacter lyticus (EC 3.4.24.-).     

Specificity of the action of lysoamidase on Staphylococcus aureus 209P cell walls

Specificity of Staphylococcus aureus 209P cell wall hydrolysis by the L1 and L2-bacteriolytic enzymes from lysoamidase lytic complex was studied. L1-peptidase was shown to display both glycyl-glycine endopeptidase and N-acetylmuramyl-L-alanine amidase enzymatic activities on the S. aureus peptidoglycan molecule, whereas L2-peptidase acts as N-acetylmuramyl-L-alanine amidase.     

Influence of Acidic Exopolysaccharide of Xanthomonas campestris IBPM 124 on the Kinetic Parameters of Extracellular Bacteriolytic Enzymes

Interactions of a negatively charged exopolysaccharide of Xanthomonas campestris IBPM 124 with its extracellular enzymes (muramidase, endopeptidase, and neutral phosphatase) and also with egg lysozyme, lysostaphin, muramidase of Streptomyces globisporus, and a bacteriolytic enzyme complex of Streptomyces albus were studied. All these enzymes were positively charged under the conditions of their maximal activity. It was shown that interaction of the acidic exopolysaccharide from X. campestris with these enzymes changed their kinetic parameters. The change was either positive (increase in reaction rate) or negative (decrease in reaction rate) and depended on the enzyme and type of substrate cleaved. Due to such interactions, the acidic exopolysaccharide secreted by X. campestris into the environment not only retained and transported positively charged exoenzymes into the near-cellular space, but also regulated their activity.     

The Mechanism of Action of the Extracellular Bacteriolytic Enzymes of Lysobacter sp. on Gram-Positive Bacteria: The Role of the Cell Wall Anionic Polymers of Target Bacteria

The study of the extracellular bacteriolytic enzymes of Lysobacter sp. showed that they can efficiently hydrolyze the peptidoglycan of gram-positive bacteria provided that there is an electrostatic interaction of these enzymes with the cell wall anionic polymers, teichoic and teichuronic acids in particular. The hydrolytic action of bacteriolytic enzymes on the cell wall largely depends on the negative charge of the teichoic and teichuronic acids rather than on their chemical composition.