Regulation of active site coupling in glutamine-dependent NAD(+) synthetase.

Abstract

NAD(+) is an essential metabolite both as a cofactor in energy metabolism and redox homeostasis and as a regulator of cellular processes. In contrast to humans, Mycobacterium tuberculosis NAD(+) biosynthesis is absolutely dependent on the activity of a multifunctional glutamine-dependent NAD(+) synthetase, which catalyzes the ATP-dependent formation of NAD(+) at the synthetase domain using ammonia derived from L-glutamine in the glutaminase domain. Here we report the kinetics and structural characterization of M. tuberculosis NAD(+) synthetase. The kinetics data strongly suggest tightly coupled regulation of the catalytic activities. The structure, the first of a glutamine-dependent NAD(+) synthetase, reveals a homooctameric subunit organization suggesting a tight dependence of catalysis on the quaternary structure, a 40-A intersubunit ammonia tunnel and structural elements that may be involved in the transfer of information between catalytic sites.

• Authors: Nicole LaRonde-LeBlanc, Melissa Resto, Barbara Gerratana
• Journal: Nature structural & molecular biology (Nat Struct Mol Biol) Vol. 16 Issue 4 Pg. 421-9 (Apr 2009) ISSN: 1545-9985 [Electronic] United States
• PMID: 19270703 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Protein Subunits
• Glutamine
• NAD
• Ammonia
• Amide Synthases
• NAD+ synthase

Topics

• Amide Synthases (chemistry)
• Ammonia (metabolism)
• Catalytic Domain
• Crystallography, X-Ray
• Glutamine (metabolism)
• Kinetics
• Models, Molecular
• Mycobacterium tuberculosis (enzymology)
• NAD (metabolism)
• Protein Multimerization
• Protein Structure, Quaternary
• Protein Subunits