Show simple item record

Files in this item


Item metadata

dc.contributor.authorAlphey, Magnus Stephen
dc.contributor.authorFisher, Gemma
dc.contributor.authorGe, Ying
dc.contributor.authorGould, Eoin Rory
dc.contributor.authorGuerreiro Machado, Teresa Filipa
dc.contributor.authorLiu, Huanting
dc.contributor.authorFlorence, Gordon John
dc.contributor.authorNaismith, James Henderson
dc.contributor.authorda Silva, Rafael G
dc.identifier.citationAlphey , M S , Fisher , G , Ge , Y , Gould , E R , Guerreiro Machado , T F , Liu , H , Florence , G J , Naismith , J H & da Silva , R G 2018 , ' Catalytic and anticatalytic snapshots of a short-form ATP phosphoribosyltransferase ' , ACS Catalysis , vol. 8 , no. 6 , pp. 5601-5610 .
dc.identifier.otherORCID: /0000-0002-8987-5561/work/45160477
dc.identifier.otherORCID: /0000-0002-1308-8190/work/47136606
dc.identifier.otherORCID: /0000-0001-9921-4399/work/56638878
dc.identifier.otherORCID: /0000-0002-9353-3716/work/74510013
dc.descriptionThis work was supported by the University of St Andrews, a Leverhulme Trust grant (RL - 2012 - 025) to G.J.F, the Engineering and Physical Sciences Research Council (EPSRC) [grant number EP/L016419/1] via a CRITICAT Centre for Doctoral Training studentship to TFGM, and the Biotechnology and Biological Sciences Research Council (BBSRC) [grant number BB/M010996/1] via an EASTBIO Doctoral Training Partnership studentship to GF.en
dc.description.abstractAllosteric modulation of catalysis is a common regulatory strategy of flux-controlling biosynthetic enzymes. The enzyme ATP phosphoribosyltransferase (ATPPRT) catalyzes the first reaction in histidine biosynthesis, the magnesium-dependent condensation of ATP and 5-phospho-α-d-ribosyl-1-pyrophosphate (PRPP) to generate N1-(5-phospho-β-d-ribosyl)-ATP (PRATP) and pyrophosphate (PPi). ATPPRT is allosterically inhibited by the final product of the pathway, histidine. Hetero-octameric ATPPRT consists of four catalytic subunits (HisGS) and four regulatory subunits (HisZ) engaged in intricate catalytic regulation. HisZ enhances HisGS catalysis in the absence of histidine while mediating allosteric inhibition in its presence. Here we report HisGS structures for the apoenzyme and complexes with substrates (PRPP, PRPP-ATP, PRPP-ADP), product (PRATP), and inhibitor (AMP), along with ATPPRT holoenzyme structures in complexes with substrates (PRPP, PRPP-ATP, PRPP-ADP) and product (PRATP). These 10 crystal structures provide an atomic view of the catalytic cycle and allosteric activation of Psychrobacter arcticus ATPPRT. In both ternary complexes with PRPP-ATP, the adenine ring is found in an anticatalytic orientation, rotated 180° from the catalytic rotamer. Arg32 interacts with phosphate groups of ATP and PRPP, bringing the substrates in proximity for catalysis. The negative charge repulsion is further attenuated by a magnesium ion sandwiched between the α- and β-phosphate groups of both substrates. HisZ binding to form the hetero-octamer brings HisGS subunits closer together in a tighter dimer in the Michaelis complex, which poises Arg56 from the adjacent HisGS molecule for cross-subunit stabilization of the PPi leaving group at the transition state. The more electrostatically preorganized active site of the holoenzyme likely minimizes the reorganization energy required to accommodate the transition state. This provides a structural basis for allosteric activation in which chemistry is accelerated by facilitating leaving group departure.
dc.relation.ispartofACS Catalysisen
dc.subjectATP phosphoribosyltransferaseen
dc.subjectCatalytic activationen
dc.subjectQD Chemistryen
dc.subjectQH301 Biologyen
dc.titleCatalytic and anticatalytic snapshots of a short-form ATP phosphoribosyltransferaseen
dc.typeJournal articleen
dc.contributor.sponsorThe Leverhulme Trusten
dc.contributor.institutionUniversity of St Andrews. School of Biologyen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. Biomedical Sciences Research Complexen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.description.statusPeer revieweden

This item appears in the following Collection(s)

Show simple item record