1EE1: Crystal Structure Of Nh3-dependent Nad+ Synthetase From Bacillus Subtilis Complexed With One Molecule Atp, Two Molecules Deamido-nad+ And One Mg2+ Ion

Citation:
Abstract
The NH(3)-dependent NAD(+) synthetase (NADS) participates in the biosynthesis of nicotinamide adenine dinucleotide (NAD(+)) by transforming nicotinic acid adenine dinucleotide (NaAD) to NAD(+). The structural behavior of the active site, including stabilization of flexible loops 82-87 and 204-225, has been studied by determination of the crystal structures of complexes of NADS with natural substrates and a substrate analog. Both loops are stabilized independently of NaAD and solely from the ATP-binding site. Analysis of the binding contacts suggests that the minor loop 82-87 is stabilized primarily by a hydrogen bond with the adenine base of ATP. Formation of a coordination complex with Mg(2+) in the ATP-binding site may contribute to the stabilization of the major loop 204-225. The major loop has a role in substrate recognition and stabilization, in addition to the protection of the reaction intermediate described previously. A second and novel Mg(2+) position has been observed closer to the NaAD-binding site in the structure crystallized at pH 7.5, where the enzyme is active. This could therefore be the catalytically active Mg(2+).
PDB ID: 1EE1Download
MMDB ID: 16370
PDB Deposition Date: 1997
Updated in MMDB: 2007/11
Experimental Method:
x-ray diffraction
Resolution: 2.06  Å
Source Organism:
Similar Structures:
Biological Unit for 1EE1: dimeric; determined by author and by software (PISA)
Molecular Components in 1EE1
Label Count Molecule
Proteins (2 molecules)
2
Nh(3)-dependent Nad(+) Synthetase(Gene symbol: nadE)
Molecule annotation
Chemicals (4 molecules)
1
1
2
2
3
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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