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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
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Structural insights into the novel diadenosine 5',5‴-P¹,P⁴-tetraphosphate phosphorylase from Mycobacterium

Shigetarou Mori1, Keigo Shibayama, Jun-Ichi Wachino

  • 1Department of Bacteriology II, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama-shi, Tokyo 208-0011, Japan. mshige@nig.go.jp

Journal of Molecular Biology
|May 14, 2011
PubMed

Insights

Rv2613c, a Mycobacterium tuberculosis protein, acts as a diadenosine tetraphosphate (Ap4A) phosphorylase. Its unique active site structure, distinct from related hydrolases, provides insights for developing new tuberculosis treatments.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Microbiology

Background:

  • Rv2613c is a diadenosine 5',5‴-P(1),P(4)-tetraphosphate (Ap4A) phosphorylase from Mycobacterium tuberculosis H37Rv.
  • Sequence analysis places Rv2613c within the histidine triad (HIT) motif superfamily, sharing characteristics with both Ap(n)A hydrolases and Ap4A phosphorylases.

Purpose of the Study:

  • To determine the crystal structure of Rv2613c, the first reported structure for an Ap(n)A phosphorylase.
  • To elucidate the structural basis for Rv2613c's catalytic activity and substrate binding.

Main Methods:

  • X-ray crystallography to determine the 3D structure of Rv2613c.
  • Site-directed mutagenesis to analyze the role of key active-site residues.
  • Sequence analysis to compare Rv2613c with related proteins.

Main Results:

  • The crystal structure of Rv2613c revealed similarity to other HIT superfamily proteins but with distinct active-site residues (Asn139, Gly146, Ser147).
  • Mutagenesis studies identified Asn139, Gly146, and Ser147 as crucial for catalysis, with Asn139 playing a critical role.
  • The tetrameric structure and Trp160 were implicated in forming the Ap4A binding site.

Conclusions:

  • The unique structural features of Rv2613c's active site explain its phosphorylase activity.
  • These findings provide a structural foundation for designing novel, structure-based inhibitors against Mycobacterium tuberculosis.

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