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

Benjamin J. Read, Gemma Fisher, Oliver L. R. Wissett, Teresa F. G. Machado, John Nicholson, John B. O. Mitchell, Rafael G. da Silva*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
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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.
Original languageEnglish
Pages (from-to)197-209
Number of pages13
JournalACS Infectious Diseases
Issue number1
Early online date20 Dec 2021
Publication statusPublished - 14 Jan 2022


  • Kinetic mechanism
  • ATP phosphoribosyltransferase
  • Enzyme inhibition
  • Protein interaction
  • Acinetobacter baumannii


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