Allosteric Inhibition of Acinetobacter baumannii ATP Phosphoribosyltransferase by Protein:Dipeptide and Protein:Protein Interactions

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 N 1-(5-phospho-β-d-ribosyl)-ATP (PRATP) and pyrophosphate. Catalytic (HisGS) and regulatory (HisZ) subun...

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Bibliographic Details
Published in:ACS infectious diseases 2022-01, Vol.8 (1), p.197-209
Main Authors: Read, Benjamin J, Fisher, Gemma, Wissett, Oliver L. R, Machado, Teresa F. G, Nicholson, John, Mitchell, John B. O, da Silva, Rafael G
Format: Article
Language:English
Subjects:
Acinetobacter baumannii - metabolism
ATP Phosphoribosyltransferase - genetics
ATP Phosphoribosyltransferase - metabolism
Dipeptides
Histidine
Kinetics
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Summary: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 N 1-(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.
ISSN:2373-8227
2373-8227
DOI:10.1021/acsinfecdis.1c00539