Cargando…

Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine

[Image: see text] ATP phosphoribosyltransferase (ATPPRT) catalyzes the first step of histidine biosynthesis, being allosterically inhibited by the final product of the pathway. Allosteric inhibition of long-form ATPPRTs by histidine has been extensively studied, but inhibition of short-form ATPPRTs...

Descripción completa

Detalles Bibliográficos
Autores principales: Thomson, Catherine M., Alphey, Magnus S., Fisher, Gemma, da Silva, Rafael G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2019
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685669/
https://www.ncbi.nlm.nih.gov/pubmed/31251578
http://dx.doi.org/10.1021/acs.biochem.9b00282
_version_ 1783442439805075456
author Thomson, Catherine M.
Alphey, Magnus S.
Fisher, Gemma
da Silva, Rafael G.
author_facet Thomson, Catherine M.
Alphey, Magnus S.
Fisher, Gemma
da Silva, Rafael G.
author_sort Thomson, Catherine M.
collection PubMed
description [Image: see text] ATP phosphoribosyltransferase (ATPPRT) catalyzes the first step of histidine biosynthesis, being allosterically inhibited by the final product of the pathway. Allosteric inhibition of long-form ATPPRTs by histidine has been extensively studied, but inhibition of short-form ATPPRTs is poorly understood. Short-form ATPPRTs are hetero-octamers formed by four catalytic subunits (HisG(S)) and four regulatory subunits (HisZ). HisG(S) alone is catalytically active and insensitive to histidine. HisZ enhances catalysis by HisG(S) in the absence of histidine but mediates allosteric inhibition in its presence. Here, steady-state and pre-steady-state kinetics establish that histidine is a noncompetitive inhibitor of short-form ATPPRT and that inhibition does not occur by dissociating HisG(S) from the hetero-octamer. The crystal structure of ATPPRT in complex with histidine and the substrate 5-phospho-α-d-ribosyl-1-pyrophosphate was determined, showing histidine bound solely to HisZ, with four histidine molecules per hetero-octamer. Histidine binding involves the repositioning of two HisZ loops. The histidine-binding loop moves closer to histidine to establish polar contacts. This leads to a hydrogen bond between its Tyr263 and His104 in the Asp101–Leu117 loop. The Asp101–Leu117 loop leads to the HisZ–HisG(S) interface, and in the absence of histidine, its motion prompts HisG(S) conformational changes responsible for catalytic activation. Following histidine binding, interaction with the histidine-binding loop may prevent the Asp101–Leu117 loop from efficiently sampling conformations conducive to catalytic activation. Tyr263Phe-PaHisZ-containing PaATPPRT, however, is less susceptible though not insensitive to histidine inhibition, suggesting the Tyr263–His104 interaction may be relevant to yet not solely responsible for transmission of the allosteric signal.
format Online
Article
Text
id pubmed-6685669
institution National Center for Biotechnology Information
language English
publishDate 2019
publisher American Chemical Society
record_format MEDLINE/PubMed
spelling pubmed-66856692019-08-08 Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine Thomson, Catherine M. Alphey, Magnus S. Fisher, Gemma da Silva, Rafael G. Biochemistry [Image: see text] ATP phosphoribosyltransferase (ATPPRT) catalyzes the first step of histidine biosynthesis, being allosterically inhibited by the final product of the pathway. Allosteric inhibition of long-form ATPPRTs by histidine has been extensively studied, but inhibition of short-form ATPPRTs is poorly understood. Short-form ATPPRTs are hetero-octamers formed by four catalytic subunits (HisG(S)) and four regulatory subunits (HisZ). HisG(S) alone is catalytically active and insensitive to histidine. HisZ enhances catalysis by HisG(S) in the absence of histidine but mediates allosteric inhibition in its presence. Here, steady-state and pre-steady-state kinetics establish that histidine is a noncompetitive inhibitor of short-form ATPPRT and that inhibition does not occur by dissociating HisG(S) from the hetero-octamer. The crystal structure of ATPPRT in complex with histidine and the substrate 5-phospho-α-d-ribosyl-1-pyrophosphate was determined, showing histidine bound solely to HisZ, with four histidine molecules per hetero-octamer. Histidine binding involves the repositioning of two HisZ loops. The histidine-binding loop moves closer to histidine to establish polar contacts. This leads to a hydrogen bond between its Tyr263 and His104 in the Asp101–Leu117 loop. The Asp101–Leu117 loop leads to the HisZ–HisG(S) interface, and in the absence of histidine, its motion prompts HisG(S) conformational changes responsible for catalytic activation. Following histidine binding, interaction with the histidine-binding loop may prevent the Asp101–Leu117 loop from efficiently sampling conformations conducive to catalytic activation. Tyr263Phe-PaHisZ-containing PaATPPRT, however, is less susceptible though not insensitive to histidine inhibition, suggesting the Tyr263–His104 interaction may be relevant to yet not solely responsible for transmission of the allosteric signal. American Chemical Society 2019-06-25 2019-07-16 /pmc/articles/PMC6685669/ /pubmed/31251578 http://dx.doi.org/10.1021/acs.biochem.9b00282 Text en Copyright © 2019 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Thomson, Catherine M.
Alphey, Magnus S.
Fisher, Gemma
da Silva, Rafael G.
Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title_full Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title_fullStr Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title_full_unstemmed Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title_short Mapping the Structural Path for Allosteric Inhibition of a Short-Form ATP Phosphoribosyltransferase by Histidine
title_sort mapping the structural path for allosteric inhibition of a short-form atp phosphoribosyltransferase by histidine
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685669/
https://www.ncbi.nlm.nih.gov/pubmed/31251578
http://dx.doi.org/10.1021/acs.biochem.9b00282
work_keys_str_mv AT thomsoncatherinem mappingthestructuralpathforallostericinhibitionofashortformatpphosphoribosyltransferasebyhistidine
AT alpheymagnuss mappingthestructuralpathforallostericinhibitionofashortformatpphosphoribosyltransferasebyhistidine
AT fishergemma mappingthestructuralpathforallostericinhibitionofashortformatpphosphoribosyltransferasebyhistidine
AT dasilvarafaelg mappingthestructuralpathforallostericinhibitionofashortformatpphosphoribosyltransferasebyhistidine