Collagen degrading activity associated with Mycobacterium species

Background-The mechanism of Mycobacterium tuberculosis penetration into tis sues is poorly understood but it is reasonable to assume that there is a co ntribution from proteases capable of disrupting the extracellular matrix of the pulmonary epithelium and the blood vessels. A study was undertaken to identify and characterise collagen degrading activity of M tuberculosis. Methods-Culture filtrate protein extract (CFPE) was obtained from reference mycobacterial strains and mycobacteria isolated from patients with tubercu losis. The collagen degrading activity of CFPE was determined according to the method of Johnson-Wint using H-3-type I collagen. The enzyme was identi fied by the Birkedal-Hansen and Taylor method and its molecular mass determ ined by SDS-PAGE and Sephacryl S-300 gel filtration chromatography using an electroelution purified enzyme. Results-CFPE from Mycobacterium tuberculosis strain H37Rv showed collagenol ytic activity that was four times higher than that of the avirulent strain H37Ra. The 75 kDa enzyme responsible was divalent cation dependent. Other m ycobacterial species and those isolated from patients with tuberculosis als o had collagen degrading activity. Conclusions-Mycobacterium species possess a metalloprotease with collagen d egrading activity. The highest enzymatic activity was found in the virulent reference strain H37Rv.