1nsy
From Proteopedia
CRYSTAL STRUCTURE OF NH3-DEPENDENT NAD+ SYNTHETASE FROM BACILLUS SUBTILIS
Overview
NAD+ synthetase catalyzes the last step in the biosynthesis of nicotinamide adenine dinucleotide. The three-dimensional structure of NH3-dependent NAD+ synthetase from Bacillus subtilis, in its free form and in complex with ATP, has been solved by X-ray crystallography (at 2.6 and 2.0 angstroms resolution, respectively) using a combination of multiple isomorphous replacement and density modification techniques. The enzyme consists of a tight homodimer with alpha/beta subunit topology. The catalytic site is located at the parallel beta-sheet topological switch point, where one AMP molecule, one pyrophosphate and one Mg2+ ion are observed. Residue Ser46, part of the neighboring 'P-loop', is hydrogen bonded to the pyrophosphate group, and may play a role in promoting the adenylation of deamido-NAD+ during the first step of the catalyzed reaction. The deamido-NAD+ binding site, located at the subunit interface, is occupied by one ATP molecule, pointing towards the catalytic center. A conserved structural fingerprint of the catalytic site, comprising Ser46, is very reminiscent of a related protein region observed in glutamine-dependent GMP synthetase, supporting the hypothesis that NAD+ synthetase belongs to the newly discovered family of 'N-type' ATP pyrophosphatases.
About this Structure
1NSY is a Single protein structure of sequence from Bacillus subtilis. Full crystallographic information is available from OCA.
Reference
Crystal structure of NH3-dependent NAD+ synthetase from Bacillus subtilis., Rizzi M, Nessi C, Mattevi A, Coda A, Bolognesi M, Galizzi A, EMBO J. 1996 Oct 1;15(19):5125-34. PMID:8895556 Page seeded by OCA on Sat May 3 02:56:25 2008
