Characterization of differential pore-forming activities of ESAT-6 proteins from Mycobacterium tuberculosis and Mycobacterium smegmatis

FEBS Lett. 2016 Feb;590(4):509-19. doi: 10.1002/1873-3468.12072. Epub 2016 Feb 7.

Abstract

Mycobacterium tuberculosis ESAT-6 (MtbESAT-6) plays essential roles in pathogenesis. MtbESAT-6 exhibits a unique pore-forming activity (PFA) that is not found in its ortholog from non-pathogenic Mycobacterium smegmatis (MsESAT-6). Here, we characterized the differential PFAs and found that exchange of I25-H26/T25-A26 between two proteins reciprocally affected their PFAs. MtbESAT-6(IH/TA) had ~ 40% reduction, while MsESAT-6(TA/IH) fully acquired its activity similar to MtbESAT-6. Mutations of A17E, K38T, N67L or R74Q on MtbESAT-6(IH/TA) further reduced the activity, with MtbESAT-6(IH/TA-17) being the lowest. This study suggests I25-H26 as the pH-sensor essential for MsESAT-6 to fully acquire the activity, while multiple residues contributed to MtbESAT-6 PFA.

Keywords: ESAT-6; Mycobacterium tuberculosis; pathogenesis; pore-forming activity; virulence factor.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antigens, Bacterial / chemistry
  • Antigens, Bacterial / genetics
  • Antigens, Bacterial / metabolism*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Hydrogen-Ion Concentration
  • Molecular Sequence Data
  • Mutation
  • Mycobacterium smegmatis / genetics
  • Mycobacterium smegmatis / metabolism*
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / metabolism*
  • Porins / genetics
  • Porins / metabolism*

Substances

  • Antigens, Bacterial
  • Bacterial Proteins
  • ESAT-6 protein, Mycobacterium tuberculosis
  • Porins