Structural highlights
FunctionHIS1_CAMJR Catalyzes the condensation of ATP and 5-phosphoribose 1-diphosphate to form N'-(5'-phosphoribosyl)-ATP (PR-ATP). Has a crucial role in the pathway because the rate of histidine biosynthesis seems to be controlled primarily by regulation of HisG enzymatic activity. Publication Abstract from PubMedATP-phosphoribosyltransferase (ATP-PRT) catalyses the first committed step of histidine biosynthesis in plants and micro-organisms. Two forms of ATP-PRT have been reported, which differ in their molecular architecture and mechanism of allosteric regulation. The short-form ATP-PRT is a hetero-octamer, with four HisG chains that comprise only the catalytic domains and four separate chains of HisZ required for allosteric regulation by histidine. The long-form ATP-PRT is homohexameric, with each chain comprising two catalytic domains and a covalently linked regulatory domain that binds histidine as an allosteric inhibitor. Here, we describe a truncated long-form ATP-PRT from Campylobacter jejuni devoid of its regulatory domain ( Cje ATP-PRT(core)). Results showed that Cje ATP-PRT(core) is dimeric, exhibits attenuated catalytic activity, and is insensitive to histidine, indicating the covalently linked regulatory domain plays a role in both catalysis and regulation. Crystal structures were obtained for Cje ATP-PRT(core) in complex with both substrates, and for the first time, the complete product of the reaction. These structures reveal the key features of the active site, and provide insights into how substrates move into position during catalysis. A dimeric catalytic core relates the short and long forms of ATP-phosphoribosyltransferase.,Mittelstadt G, Jiao W, Livingstone E, Moggre GJ, Nazmi AR, Parker EJ Biochem J. 2017 Dec 5. pii: BCJ20170762. doi: 10.1042/BCJ20170762. PMID:29208762[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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