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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
11:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

Amino-terminal extension present in the methionine aminopeptidase type 1c of Mycobacterium tuberculosis is

Pavitra Kanudia1, Monica Mittal, Sangaralingam Kumaran

  • 1Institute of Microbial Technology, Council of Scientific and Industrial Research, Sector 39A, Chandigarh 160 036, India.

BMC Biochemistry
|July 7, 2011
PubMed
Abstract

Insights

Mycobacterium tuberculosis methionine aminopeptidase 1c (MtMetAP1c) activity and stability are enhanced by a unique N-terminal extension. This extension regulates active site residues via an "action-at-a-distance" mechanism, a novel finding for methionine aminopeptidases.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Enzymology

Background:

  • Methionine aminopeptidases (MetAP) are essential enzymes catalyzing N-terminal methionine removal during protein synthesis.
  • This process is crucial for proper protein localization, processing, and degradation in all organisms.
  • MetAP activity is mandatory for 50-70% of newly synthesized proteins.

Purpose of the Study:

  • To investigate the biochemical and structural properties of two metalloproteases from Mycobacterium tuberculosis: MtMetAP1a and MtMetAP1c.
  • To elucidate the role of specific structural features, particularly the N-terminal extension of MtMetAP1c, in enzyme function.

Main Methods:

  • Gene cloning and expression of histidine-tagged MtMetAP1a and MtMetAP1c in E. coli.
  • Enzyme activity assays and circular dichroism spectroscopy for stability studies.
  • Protein structure modeling, site-directed mutagenesis, and molecular dynamic simulations.

Main Results:

  • MtMetAP1c exhibited a significantly higher enzyme turnover rate than MtMetAP1a for the Met-Ala-Ser substrate.
  • MtMetAP1a demonstrated higher thermostability (up to 50 °C) compared to MtMetAP1c.
  • A unique 40-amino acid N-terminal extension in MtMetAP1c was found to contribute to its activity and stability, with Val-18 and Pro-19 identified as crucial residues.

Conclusions:

  • The N-terminal extension of MtMetAP1c plays a significant role in enzyme functionality, likely through an "action-at-a-distance" mechanism regulating active site residues.
  • This study reports for the first time the unique functional contribution of an N-terminal extension in methionine aminopeptidases.

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