3qpy

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Crystal structure of a mutant (K57A) of 3-deoxy-D-manno-octulosonate 8-phosphate synthase (KDO8PS) from Neisseria meningitidis

Structural highlights

3qpy is a 4 chain structure with sequence from Neisseria meningitidis MC58. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.95Å
Ligands:	, ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

KDSA_NEIMB

Publication Abstract from PubMed

3-Deoxy-D-manno-octulosonate 8-phosphate synthase (KDO8PS) catalyzes the reaction between three-carbon phosphoenolpyruvate (PEP) and five-carbon D-arabinose 5-phosphate (A5P), generating KDO8P, a key intermediate in the biosynthetic pathway to 3-deoxy-D-manno-octulosonate, a component of the lipopolysaccharide of the Gram-negative bacterial cell wall. Both metal-dependent and metal-independent forms of KDO8PS have been characterized. KDO8PS is evolutionarily and mechanistically related to the first enzyme of the shikimate pathway, the obligately divalent metal-ion-dependent 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) that couples PEP and four-carbon D-erythrose 4-phosphate (E4P) to give DAH7P. In KDO8PS an absolutely conserved KANRS motif forms part of the A5P binding site, whereas in DAH7PS an absolutely conserved KPR(S/T) motif accommodates E4P. Here, we have characterized four mutants of this motif (AANRS, KAARS, KARS and KPRS) in metal-dependent KDO8PS from Acidithiobacillus ferrooxidans and metal-independent KDO8PS from Neisseria meningitidis in order to test the roles of the universal Lys and the AlaAsn portion of the KANRS motif. The X-ray structures, determined for the N. meningitidis KDO8PS mutants, indicated no gross structural penalty resulting from mutation, but the subtle changes observed in the active sites of these mutant proteins correlated with their altered catalytic function: 1) the AANRS mutations destroyed catalytic activity; 2) the KAARS mutations lowered substrate selectivity, as well as activity; 3) replacing KANRS by KARS or KPRS destroyed KDO8PS activity, but did not produce a functional DAH7PS. Thus, Lys is critical to catalysis and other changes are necessary to switch substrate specificity for both the metal-independent and metal-dependent forms of these enzymes.

Targeting the role of a key conserved motif for substrate selection and catalysis by 3-deoxy-D-manno-octulosonate 8-phosphate synthase.,Allison TM, Hutton RD, Cochrane FC, Yeoman JA, Jameson GB, Parker EJ Biochemistry. 2011 Mar 25. PMID:21438567^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Allison TM, Hutton RD, Cochrane FC, Yeoman JA, Jameson GB, Parker EJ. Targeting the role of a key conserved motif for substrate selection and catalysis by 3-deoxy-D-manno-octulosonate 8-phosphate synthase. Biochemistry. 2011 Mar 25. PMID:21438567 doi:10.1021/bi200251f