Partial characterization of a major autolysin from Mycobacterium phlei

dAutolytic enzyme profiles of fast- and slow-growing mycobacteria were exam ined using SDS-PACE zymography with incorporated mycobacterial peptidoglyca n sacculi as substrate. Each species tested (Mycobacterium phlei, Mycobacte rium smegmatis, Mycobacterium aurum, Mycobacterium fortuitum and Mycobacter ium kansasii) appeared to produce a different set of enzymes on the basis o f differing number and molecular masses. A major autolysin from M. phlei wa s purified to apparent homogeneity by DEAE-cellulose chromatography, prepar ative gel electrophoresis and Mono Q FPLC. This enzyme had an estimated mol ecular mass of 38 kDa, an isoelectric point of 5.5 and a ph optimum of ph 7 .5. Digestion of purified peptidoglycan by the enzyme resulted in the appea rance of reducing sugars, suggesting that the 38 kDa autolysin is a beta-gl ycosidase. Partial internal amino acid sequence of the autolysin was determ ined and should facilitate identification, cloning and overexpression of th e encoding gene.