A Novel Lipase Belonging to the Hormone-sensitive Lipase Family Induced under Starvation to Utilize Stored Triacylglycerol in Mycobacterium tuberculosis

摘要: Twenty-four putative lipase/esterase genes of Mycobacterium tuberculosis H37Rv were expressed in Escherichia coli and assayed for long-chain triacylglycerol (TG) hydrolase activity. We show here that the product Rv3097c (LIPY) hydrolyzed TG with high specific LIPY was purified after solubilization from inclusion bodies; enzyme displayed a K(m) 7.57 mM V(max) 653.3 nmol/mg/min triolein optimal activity between pH 8.0 9.0. inhibited by active serine-directed reagents inactivated at temperatures above 37 degrees C. Detergents their critical micellar concentrations divalent cations LIPY. The N-terminal half showed sequence homology proline glutamic acid-polymorphic GC-rich repetitive sequences protein family M. tuberculosis. C-terminal possesses amino acid domains homologous hormone-sensitive lipase conserved active-site motif GDSAG. shows low identity annotated lipases other bacterial lipases. demonstrate hypoxic cultures tuberculosis, which had accumulated TG, stored when subjected to nutrient starvation. Under such conditions, lipY induced more than all lipases, suggesting central role it utilization TG. also lipY-deficient mutant, drastically decreased under nutrient-deprived condition. Thus, may be responsible during dormancy reactivation pathogen.