Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids - Archive ouverte HAL Access content directly
Journal Articles Biochemical Journal Year : 2007

Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids

Karen Côtes
  • Function : Author
Rabeb Dhouib
  • Function : Author
Isabelle Douchet
  • Function : Author
Henri Chahinian
  • Function : Author
Alain de Caro
  • Function : Author
Frédéric Carrière
Stéphane Canaan
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Abstract

The Rv0183 gene of the M. tuberculosis H37Rv strain, which has been annotated as a probable lysophospholipase, was cloned and expressed in E. coli. The purified Rv0183 protein did not show any activity when lysophospholipid substrates were used, but preferentially hydrolyzed monoacylglycerol substrates with a specific activity of 290 U.mg -1} at 37°C. Rv0183 hydrolyzes both long chain di- and triacylglycerols, as determined using the monomolecular film technique, although the turnover was lower than with monoacylglycerol. The enzyme shows an optimum activity at pH values ranging from 7.5 to 9.0 using monoolein as substrate and is inactivated by serine esterase inhibitors such as E600, PMSF and tetrahydrolipstatin. The catalytic triad is composed of Ser 110, Asp 226 and His 256, as confirmed by the results of site directed mutagenesis. Rv0183 shows 35% sequence identity with the human and mouse monoglyceride lipases and well below 15% with the other bacterial lipases characterized so far. Homologs of Rv0183 can be identified in other mycobacterial genomes such as M. bovis, M. smegmatis, and even M. leprae, which is known to contain a low number of genes involved in the replication process within the host cells. The results of immunolocalization studies performed with polyclonal antibodies raised against the purified recombinant Rv0183 suggested that the enzyme was present only in the cell wall and the culture medium of M. tuberculosis. Our results identify Rv0183 as the first exported lipolytic enzyme to be characterized in M. tuberculosis and suggest that Rv0183 may be involved in the degradation of the host cell lipids.

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hal-00478817 , version 1 (30-04-2010)

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Karen Côtes, Rabeb Dhouib, Isabelle Douchet, Henri Chahinian, Alain de Caro, et al.. Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids. Biochemical Journal, 2007, 408 (3), pp.417-427. ⟨10.1042/BJ20070745⟩. ⟨hal-00478817⟩

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