1ytk

File:1ytk.gif

spinqualitylabelsall models 1ytk, resolution 2.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of a nicotinate phosphoribosyltransferase from Thermoplasma acidophilum with nicotinate mononucleotide

OverviewOverview

We have determined the crystal structure of nicotinate, phosphoribosyltransferase from Themoplasma acidophilum (TaNAPRTase). The, TaNAPRTase has three domains, an N-terminal domain, a central functional, domain, and a unique C-terminal domain. The crystal structure revealed, that the functional domain has a type II phosphoribosyltransferase fold, that may be a common architecture for both nicotinic acid and quinolinic, acid (QA) phosphoribosyltransferases (PRTase) despite low sequence, similarity between them. Unlike QAPRTase, TaNAPRTase has a unique extra, C-terminal domain containing a zinc knuckle-like motif containing 4, cysteines. The TaNAPRTase forms a trimer of dimers in the crystal. The, active site pocket is formed at dimer interfaces. The complex structures, with phosphoribosylpyrophosphate (PRPP) and nicotinate mononucleotide, (NAMN) showed, surprisingly, that functional residues lining on the active, site of TaNAPRTase are quite different from those of QAPRTase, although, their substrates are quite similar to each other. The phosphate moiety of, PRPP and NAMN is anchored to the phosphate-binding loops formed by, backbone amides, as found in many alpha/beta barrel enzymes. The, pyrophosphate moiety of PRPP is located at the entrance of the active site, pocket, whereas the nicotinate moiety of NAMN is located deep inside., Interestingly, the nicotinate moiety of NAMN is intercalated between, highly conserved aromatic residues Tyr(21) and Phe(138). Careful, structural analyses combined with other NAPRTase sequence subfamilies, reveal that TaNAPRTase represents a unique sequence subfamily of NAPRTase., The structures of TaNAPRTase also provide valuable insight for other, sequence subfamilies such as pre-B cell colony-enhancing factor, known to, have nicotinamide phosphoribosyltransferase activity.

About this StructureAbout this Structure

1YTK is a Single protein structure of sequence from Thermoplasma acidophilum dsm 1728 with NCN and TRS as ligands. Active as Nicotinate phosphoribosyltransferase, with EC number 2.4.2.11 Full crystallographic information is available from OCA.

ReferenceReference

Crystal structure of a nicotinate phosphoribosyltransferase from Thermoplasma acidophilum., Shin DH, Oganesyan N, Jancarik J, Yokota H, Kim R, Kim SH, J Biol Chem. 2005 May 6;280(18):18326-35. Epub 2005 Mar 6. PMID:15753098

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