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Modulation of the Activity of Mycobacterium tuberculosis LipY by Its PE Domain

Christopher K Garrett1, Lindsey J Broadwell2, Cassandra K Hayne1

  • 1Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.

Plos One
|August 14, 2015
PubMed

Insights

The PE domain of Mycobacterium tuberculosis LipY protein inhibits its lipase activity. This inhibition requires the PE domain to remain attached to LipY, but does not affect the enzyme's thermal stability.

Area of Science:

  • Microbiology
  • Protein Biochemistry
  • Tuberculosis Pathogenesis

Background:

  • Mycobacterium tuberculosis possesses over 160 PE/PPE genes, contributing to virulence.
  • PE/PPE proteins are secreted via ESX secretion systems, including LipY exported by ESX-5.
  • LipY contains a triglyceride lipase domain and a PE domain; the PE domain is cleaved upon export.

Purpose of the Study:

  • To investigate the regulatory role of LipY's PE domain on its enzymatic activity.
  • To confirm the inhibitory function of the PE domain on LipY's lipase activity.
  • To assess the impact of the PE domain on LipY's thermal stability.

Main Methods:

  • Developed an improved purification method for LipY variants using detergent micelles.
  • Conducted enzymatic assays to measure LipY activity.
  • Determined the melting temperatures of full-length LipY and a variant lacking the PE domain (LipYΔPE).

Main Results:

  • Confirmed that the PE domain down-regulates LipY's enzymatic activity.
  • Established that PE domain-mediated inhibition is dependent on its attachment to LipY.
  • Found no significant difference in thermal stability between full-length LipY and LipYΔPE.

Conclusions:

  • LipY's PE domain actively down-regulates its lipase activity.
  • The PE domain's inhibitory effect is contingent on its physical association with the lipase.
  • The PE domain does not influence the overall thermal stability of the LipY enzyme.

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