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Functional characterization of EngA(MS), a P-loop GTPase of Mycobacterium smegmatis

Nisheeth Agarwal1, Madhu Pareek, Preeti Thakur

  • 1Vaccine and Infectious Disease Research Center, Translational Health Science and Technology Institute, Gurgaon, Haryana, India. nisheeth@thsti.res.in

Plos One
|April 17, 2012
PubMed

Insights

Mycobacterium smegmatis EngA (MSMEG_3738) is a conserved P-loop GTPase that binds to ribosomal subunits. GTP binding is crucial for its interaction with the 50S ribosomal subunit, regulated by its N-terminal domain.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Bacterial P-loop GTPases regulate essential cellular processes like cell division and ribosomal assembly.
  • While conserved in mycobacteria, the specific functions of most P-loop GTPases remain unclear.
  • This study focuses on characterizing a novel P-loop GTPase from Mycobacterium smegmatis.

Purpose of the Study:

  • To characterize the function of the P-loop GTPase MSMEG_3738 (EngA(MS)) from Mycobacterium smegmatis.
  • To investigate the interaction of EngA(MS) with ribosomal components.
  • To elucidate the role of GTP and specific domains in EngA(MS) function.

Main Methods:

  • Comparative genome sequence analysis and phylogenetic analysis of MSMEG_3738.
  • Homology modeling to predict the protein structure.
  • Purification of recombinant EngA(MS) from E. coli and assessment of GTP hydrolysis activity.
  • Co-elution studies with ribosomal RNA and subunits.
  • Site-directed mutagenesis to analyze domain-specific interactions.

Main Results:

  • EngA(MS) is a highly conserved P-loop GTPase with a typical cloverleaf structure.
  • Purified EngA(MS) exhibits GTP hydrolysis activity, inhibited by GDP.
  • EngA(MS) co-purifies with 16S and 23S ribosomal RNA and associates with 30S, 50S, and 70S ribosomal subunits.
  • GTP is essential for EngA(MS) interaction with the 50S ribosomal subunit.
  • The C-terminal domain is required for GTP-dependent interaction, while the N-terminal domain regulates this interaction.

Conclusions:

  • EngA(MS) is a functional GTPase associated with the mycobacterial ribosome.
  • GTP binding and the C-terminal domain are critical for ribosome association.
  • The N-terminal domain plays a regulatory role in EngA(MS)-ribosome interaction, suggesting involvement in ribosome assembly or function.

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