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LIR motifs and the membrane-targeting domain are complementary in the function of RavZ

Sang-Won Park1, Yong-Woo Jun1, Pureum Jeon2

  • 1Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Sangju 37224, Korea.

BMB Reports
|November 15, 2019
PubMed

Insights

The bacterial protein RavZ inhibits host autophagy by removing mammalian ATG8 proteins from membranes. Both its LIR motifs and membrane-targeting domain contribute to this function through complementary, independent pathways.

Area of Science:

  • Cell Biology
  • Microbiology
  • Molecular Biology

Background:

  • Legionella pneumophila uses the RavZ effector protein to inhibit host autophagy.
  • RavZ disrupts autophagy by irreversibly deconjugating mammalian ATG8 (mATG8) proteins from autophagosome membranes.
  • The specific roles of LIR motifs within RavZ in its function were previously unclear.

Purpose of the Study:

  • To investigate the roles of LIR motifs and the membrane-targeting (MT) domain in the function of the bacterial effector protein RavZ.
  • To elucidate the mechanisms by which RavZ inhibits host autophagy.

Main Methods:

  • Utilized RavZ mutants lacking mATG8 binding or the MT domain.
  • Assessed the ability of wild-type and mutant RavZ to delipidate mATG8-phosphatidylethanolamine (PE).

Main Results:

  • A RavZ mutant unable to bind mATG8 efficiently delipidated mATG8-PE.
  • A RavZ mutant lacking the MT domain showed reduced selective delipidation of mATG8-PE compared to wild-type RavZ.
  • Both LIR motifs and the MT domain contribute to RavZ's overall function.

Conclusions:

  • The LIR motifs and MT domain of RavZ play complementary roles in inhibiting host autophagy.
  • These domains appear to function through independent pathways to regulate RavZ activity.
  • RavZ's inhibition of autophagy involves both direct mATG8 interaction and membrane association.

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