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Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism.

Publication ,  Journal Article
Murray, DS; Chinnam, N; Tonthat, NK; Whitfill, T; Wray, LV; Fisher, SH; Schumacher, MA
Published in: J Biol Chem
December 13, 2013

Glutamine synthetase (GS), which catalyzes the production of glutamine, plays essential roles in nitrogen metabolism. There are two main bacterial GS isoenzymes, GSI-α and GSI-β. GSI-α enzymes, which have not been structurally characterized, are uniquely feedback-inhibited by Gln. To gain insight into GSI-α function, we performed biochemical and cellular studies and obtained structures for all GSI-α catalytic and regulatory states. GSI-α forms a massive 600-kDa dodecameric machine. Unlike other characterized GS, the Bacillus subtilis enzyme undergoes dramatic intersubunit conformational alterations during formation of the transition state. Remarkably, these changes are required for active site construction. Feedback inhibition arises from a hydrogen bond network between Gln, the catalytic glutamate, and the GSI-α-specific residue, Arg(62), from an adjacent subunit. Notably, Arg(62) must be ejected for proper active site reorganization. Consistent with these findings, an R62A mutation abrogates Gln feedback inhibition but does not affect catalysis. Thus, these data reveal a heretofore unseen restructuring of an enzyme active site that is coupled with an isoenzyme-specific regulatory mechanism. This GSI-α-specific regulatory network could be exploited for inhibitor design against Gram-positive pathogens.

Duke Scholars

Published In

J Biol Chem

DOI

EISSN

1083-351X

Publication Date

December 13, 2013

Volume

288

Issue

50

Start / End Page

35801 / 35811

Location

United States

Related Subject Headings

  • Protein Subunits
  • Protein Structure, Quaternary
  • Protein Multimerization
  • Models, Molecular
  • Kinetics
  • Isoenzymes
  • Glutamine
  • Glutamate-Ammonia Ligase
  • Feedback, Physiological
  • Biochemistry & Molecular Biology
 

Citation

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Murray, D. S., Chinnam, N., Tonthat, N. K., Whitfill, T., Wray, L. V., Fisher, S. H., & Schumacher, M. A. (2013). Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism. J Biol Chem, 288(50), 35801–35811. https://doi.org/10.1074/jbc.M113.519496
Murray, David S., Nagababu Chinnam, Nam Ky Tonthat, Travis Whitfill, Lewis V. Wray, Susan H. Fisher, and Maria A. Schumacher. “Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism.J Biol Chem 288, no. 50 (December 13, 2013): 35801–11. https://doi.org/10.1074/jbc.M113.519496.
Murray DS, Chinnam N, Tonthat NK, Whitfill T, Wray LV, Fisher SH, et al. Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism. J Biol Chem. 2013 Dec 13;288(50):35801–11.
Murray, David S., et al. “Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism.J Biol Chem, vol. 288, no. 50, Dec. 2013, pp. 35801–11. Pubmed, doi:10.1074/jbc.M113.519496.
Murray DS, Chinnam N, Tonthat NK, Whitfill T, Wray LV, Fisher SH, Schumacher MA. Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism. J Biol Chem. 2013 Dec 13;288(50):35801–35811.

Published In

J Biol Chem

DOI

EISSN

1083-351X

Publication Date

December 13, 2013

Volume

288

Issue

50

Start / End Page

35801 / 35811

Location

United States

Related Subject Headings

  • Protein Subunits
  • Protein Structure, Quaternary
  • Protein Multimerization
  • Models, Molecular
  • Kinetics
  • Isoenzymes
  • Glutamine
  • Glutamate-Ammonia Ligase
  • Feedback, Physiological
  • Biochemistry & Molecular Biology