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Separation and Fractionation of Culture Filtrate Proteins (CFPs) from Mycobacterium tuberculosis
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VapC proteins from Mycobacterium tuberculosis share ribonuclease sequence specificity but differ in regulation and

Abigail Sharrock1, Alaine Ruthe1, Emma S V Andrews1

  • 1School of Science, University of Waikato, Hamilton, New Zealand.

Plos One
|September 1, 2018
PubMed

Insights

Mycobacterium tuberculosis toxin-antitoxin systems, particularly VapBC, share ribonuclease activity targeting UAGG sequences. Differences in regulation and toxicity among VapC proteins may explain their role in Mtb growth and persistence.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Mycobacterium tuberculosis (Mtb) harbors numerous Type II toxin-antitoxin (TA) systems.
  • The VapBC family, characterized by VapC proteins with PIN domains and ribonuclease activity, is prevalent in Mtb.

Purpose of the Study:

  • To characterize the ribonuclease activity, regulation, and toxicity of five VapC proteins from Mtb.
  • To investigate the role of VapBC TA systems in Mtb growth and persistence.

Main Methods:

  • Characterization of five VapC proteins using pentaprobe RNA sequences and mass spectrometry.
  • Analysis of auto-regulation and promoter interactions for VapBC29, VapBC1, and VapBC27.
  • Expression of VapC proteins in Mycobacterium smegmatis to assess toxicity.

Main Results:

  • Five Mtb VapC proteins exhibited shared ribonuclease specificity for UAGG sequences.
  • VapBC29 demonstrated auto-regulation, while VapBC1 and VapBC27 did not, potentially due to distinct VapB protein properties.
  • VapC29 was bacteriostatic in M. smegmatis, whereas VapC1 and VapC27 showed no toxicity.
  • Specific regulation of the vapBC29 operon without cross-talk among Type II TA systems was observed.

Conclusions:

  • The conserved UAGG sequence specificity of VapC proteins is notable.
  • Variations in auto-regulation and toxicity among VapBC systems are crucial for understanding their function in Mtb survival and persistence.
  • Further research into these regulatory differences is warranted.

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