Thermostable Bacterial Collagenolytic Proteases: A Review.

Abstract

Collagenolytic proteases are widely used in the food, medical, pharmaceutical, cosmetic, and textile industries. Mesophilic collagenases exhibit collagenolytic activity under physiological conditions but have limitations in efficiently degrading collagen-rich wastes, such as collagen from fish scales, at high temperatures due to their poor thermostability. Bacterial collagenolytic proteases are members of various proteinase families, including the bacterial collagenolytic metalloproteinase M9 and the bacterial collagenolytic serine proteinase families S1, S8, and S53. Notably, C-terminal domains of collagenolytic proteases, such as the pre-peptidase C-terminal domain, polycystic kidney disease-like domain, collagen-binding domain, proprotein convertase domain, and β-jelly roll domain, exhibit collagen-binding or -swelling activity. These activities can induce conformational changes in collagen or the enzyme active sites, increasing the degradation efficiency of collagen. Thermostable bacterial collagenolytic proteases function at high temperatures, which has the advantage of increasing the degradation efficiency because heat-denatured collagen is more susceptible to proteolysis and can minimize the risk of microbial contamination. To date, only a few thermophile-derived collagenolytic proteases have been characterized. TSS, a thermostable and halotolerant subtilisin-like serine collagenolytic protease, exhibits high collagenolytic activity at 60°C. In this review, we present and summarize current research on the classification and nomenclature of thermostable and mesophilic collagenolytic proteases derived from diverse microorganisms as well as the functional roles of their C-terminal domains. Furthermore, we analyze the cleavage specificity of thermostable collagenolytic proteases in each family and comprehensively discuss the thermostable collagenolytic protease TSS.