1e3h
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(New page: 200px<br /><applet load="1e3h" size="450" color="white" frame="true" align="right" spinBox="true" caption="1e3h, resolution 2.60Å" /> '''SEMET DERIVATIVE OF ...)
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Revision as of 01:51, 25 November 2007
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SEMET DERIVATIVE OF STREPTOMYCES ANTIBIOTICUS PNPASE/GPSI ENZYME
Overview
BACKGROUND: Polynucleotide phosphorylase (PNPase) is a polyribonucleotide, nucleotidyl transferase (E.C.2.7.7.8) that degrades mRNA in prokaryotes., Streptomyces antibioticus PNPase also assays as a guanosine 3'-diphosphate, 5'-triphosphate (pppGpp) synthetase (E.C.2.7.6.5). It may function to, coordinate changes in mRNA lifetimes with pppGpp levels during the, Streptomyces lifecycle. RESULTS: The structure of S. antibioticus PNPase, without bound RNA but with the phosphate analog tungstate bound at the, PNPase catalytic sites was determined by X-ray crystallography and shows a, trimeric multidomain protein with a central channel. The structural core, has a novel duplicated architecture formed by association of two, homologous domains. The tungstate derivative structure reveals the PNPase, active site in the second of these core domains. Structure-based sequence, analysis suggests that the pppGpp synthetase active site is located in the, first core domain. CONCLUSIONS: This is the first structure of a PNPase, and shows the structural basis for the trimer assembly, the arrangement of, accessory RNA binding domains, and the likely catalytic residues of the, PNPase active site. A possible function of the trimer channel is as a, contribution to both the processivity of degradation and the regulation of, PNPase action by RNA structural elements.
About this Structure
1E3H is a Single protein structure of sequence from Streptomyces antibioticus with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
A duplicated fold is the structural basis for polynucleotide phosphorylase catalytic activity, processivity, and regulation., Symmons MF, Jones GH, Luisi BF, Structure. 2000 Nov 15;8(11):1215-26. PMID:11080643
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