Title

A novel lipase belonging to the hormone-sensitive lipase family induced under starvation to utilize stored triacylglycerol in Mycobacterium tuberculosis

Authors

Authors

C. Deb; J. Daniel; T. D. Sirakova; B. Abomoelak; V. S. Dubey;P. E. Kolattukudy

Comments

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Abbreviated Journal Title

J. Biol. Chem.

Keywords

CRYSTAL-STRUCTURE; MOUSE-TISSUES; FATTY-ACIDS; PERSISTENCE; EXPRESSION; ESTERASE; GENE; PHAGOSOMES; INFECTION; BIOLOGY; Biochemistry & Molecular Biology

Abstract

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

Journal Title

Journal of Biological Chemistry

Volume

281

Issue/Number

7

Publication Date

1-1-2006

Document Type

Article

Language

English

First Page

3866

Last Page

3875

WOS Identifier

WOS:000235275300014

ISSN

0021-9258

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