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Allosteric inhibition of Acinetobacter baumannii ATP phosphoribosyltransferase by protein:dipeptide and protein:protein Interactions

Authors :
Benjamin J. Read
Gemma Fisher
Oliver L. R. Wissett
Teresa F. G. Machado
John Nicholson
John B. O. Mitchell
Rafael G. da Silva
EPSRC
University of St Andrews. School of Biology
University of St Andrews. School of Chemistry
University of St Andrews. Biomedical Sciences Research Complex
University of St Andrews. EaSTCHEM
Publication Year :
2022

Abstract

This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) (Grant BB/M010996/1) via EASTBIO Doctoral Training Partnership studentships to B.J.R. and G.F., and by the Engineering and Physical Sciences Research Council (EPSRC) [grant number EP/L016419/1] via a CRITICAT Centre for Doctoral Training studentship to T.F.G.M. ATP phosphoribosyltransferase (ATPPRT) catalyzes the first step of histidine biosynthesis in bacteria, namely, the condensation of ATP and 5-phospho-α-d-ribosyl-1-pyrophosphate (PRPP) to generate N1-(5-phospho-β-d-ribosyl)-ATP (PRATP) and pyrophosphate. Catalytic (HisGS) and regulatory (HisZ) subunits assemble in a hetero-octamer where HisZ activates HisGS and mediates allosteric inhibition by histidine. In Acinetobacter baumannnii, HisGS is necessary for the bacterium to persist in the lung during pneumonia. Inhibition of ATPPRT is thus a promising strategy for specific antibiotic development. Here, A. baumannii ATPPRT is shown to follow a rapid equilibrium random kinetic mechanism, unlike any other ATPPRT. Histidine noncompetitively inhibits ATPPRT. Binding kinetics indicates histidine binds to free ATPPRT and to ATPPRT:PRPP and ATPPRT:ATP binary complexes with similar affinity following a two-step binding mechanism, but with distinct kinetic partition of the initial enzyme:inhibitor complex. The dipeptide histidine-proline inhibits ATPPRT competitively and likely uncompetitively, respectively, against PRPP and ATP. Rapid kinetics analysis shows His-Pro binds to the ATPPRT:ATP complex via a two-step binding mechanism. A related HisZ that shares 43% sequence identity with A. baumannii HisZ is a tight-binding allosteric inhibitor of A. baumannii HisGS. These findings lay the foundation for inhibitor design against A. baumannii ATPPRT. Postprint

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.doi.dedup.....1f8f27fefe60c1f31613e0c53eee030d