Studies on the quaternary structure of the first enzyme for histidine biosynthesis

Tebar, A. R.; Fernández, Vı́ctor M.; Martín-del-Río, Rafael

doi:10.1007/bf01943865

Cited by 17 publications

(24 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2c) and inactive higher oligomeric forms (37)(38)(39). Gel filtration experiments showed similar behavior for the mt ATP-PRTase (see "Experimental Procedures").…”

Section: Resultsmentioning

confidence: 75%

Crystal Structure of ATP Phosphoribosyltransferase fromMycobacterium tuberculosis

Cho

Sharma

Sacchettini

2003

Journal of Biological Chemistry

172

View full text Add to dashboard Cite

The N-1-(5-phosphoribosyl)-ATP transferase catalyzes the first step of the histidine biosynthetic pathway and is regulated by a feedback mechanism by the product histidine. The crystal structures of the N-1-(5-phosphoribosyl)-ATP transferase from Mycobacterium tuberculosis in complex with inhibitor histidine and AMP has been determined to 1.8 Å resolution and without ligands to 2.7 Å resolution. The active enzyme exists primarily as a dimer, and the histidine-inhibited form is a hexamer. The structure represents a new fold for a phosphoribosyltransferase, consisting of three continuous domains. The inhibitor AMP binds in the active site cavity formed between the two catalytic domains. A model for the mechanism of allosteric inhibition has been derived from conformational differences between the AMP:His-bound and apo structures.The N-1-(5Ј-phosphoribosyl)-ATP transferase (ATP-PRTase) 1 encoded by the hisG locus catalyzes the condensation of ATP with PRPP, the first reaction in the histidine biosynthetic pathway. The reaction is a Mg 2ϩ -dependent transfer of the phosphoribosyl moiety from 5Ј-phosphoribosyl 1Ј-pyrophosphate (PRPP) to the N1 nitrogen of adenosine ring of ATP yielding phosphoribosyl-ATP and inorganic pyrophosphate (PP i ) (Scheme 1) (1). The activity and the expression of ATPPRTase are regulated by feedback inhibition and by repression of the his operon in response to host iron, respectively (2, 3).Given the high energetic costs associated with the synthesis of a histidine molecule and the direct connections of the histidine pathway with purine, pyrimidine, and tryptophan biosynthesis, a multilevel regulatory control has been selectively retained in all bacteria studied to date. Whereas the transcriptional regulation based on nutrient conditions controls the steady-state level of enzyme over several bacterial generations, the feedback inhibition of ATP-PRTase serves as a fine-tuning control that provides rapid regulation of biosynthetic activity as a function of the available histidine.The ATP-PRTase-catalyzed reaction has been studied for more than 4 decades and was originally believed to proceed via the formation of a 5Ј-phosphoribosyl enzyme covalent intermediate (4, 5). Detailed kinetic studies refuted the presence of such an intermediate (6). Steady-state studies of the enzymatic reaction in both directions were consistent with a sequential mechanism (7) where ATP binding precedes binding of PRPP (8). The ATP-PRTase reaction has also been shown to be completely reversible as addition of pyrophosphate to phosphoribosyl-ATP yields ATP and PRPP (9). The synergistic inhibition of the enzyme was demonstrated to occur allosterically by histidine and competitively by AMP, ADP, or guanosine tetraphosphate (10). AMP and ADP are both competitive inhibitors with respect to PRPP and ATP (1). Histidine inhibition was first thought to be "noncompetitive" with PRPP and ATP (1). A single histidine was later proposed to interact with more than one molecule of the enzyme, in a site shown to be allosteric in natu...

show abstract

“…2c) and inactive higher oligomeric forms (37)(38)(39). Gel filtration experiments showed similar behavior for the mt ATP-PRTase (see "Experimental Procedures").…”

Section: Resultsmentioning

confidence: 75%

Crystal Structure of ATP Phosphoribosyltransferase fromMycobacterium tuberculosis

Cho

Sharma

Sacchettini

2003

Journal of Biological Chemistry

172

View full text Add to dashboard Cite

show abstract

“…We reported [2] that ATP associates the enzyme, although not so highly and specifically as histidine does. It is conceivable that EATP could substitute for ATP in association of the enzyme, and this would explain the appearance of positive cooperativity in the binding of PRPP ( fig.5).…”

Section: Discussionmentioning

confidence: 81%

“…It is known that histidine in the range 0.05 to 1 mM associates the E.coZi enzyme [2, lo]. We have previously shown by gel filtration [2] that the main species of the enzyme in the absence of ligands is the dimer, and that 0.4 mM histidine displaces the equilibrium dimer-tetramer-hexamer towards the hexamer. The same results are found by ultracentrifugation studies in the presence of 0.4 mM histidine (A. R. Tebar, unpublished experiments).…”

Section: Discussionmentioning

confidence: 99%

“…Tebar et al [2] studied the effect of PRPP on the quaternary structure of the enzyme; PRPP totally reversed the association produced by histidine, displacing the pattern toward the dimeric form. Here, when the synthetase is free of histidine, it exists preferentially as a dimer, so PRPP has no effect on the fluorescence quantum yield.…”

Section: Discussionmentioning

confidence: 99%

“…The source of the enzyme and the purification procedure have been reported [2]. Fluorescence intensities were measured in a Perkin-Elmer MFP3 spectrofluorimeter, at 22"C, adding increasing amounts of a concentrated solution of the ligand to 3 ml of enzyme solution.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Fluorescence studies of phosphoribosyladenosine triphosphate synthetase of Escherichia coli

1975

View full text Add to dashboard Cite

Campylobacter jejuni adenosine triphosphate phosphoribosyltransferase is an active hexamer that is allosterically controlled by the twisting of a regulatory tail

et al. 2016

View full text Add to dashboard Cite

Adenosine triphosphate phosphoribosyltransferase (ATP-PRT) catalyzes the first committed step of the histidine biosynthesis in plants and microorganisms. Here, we present the functional and structural characterization of the ATP-PRT from the pathogenic e-proteobacteria Campylobacter jejuni (CjeATP-PRT). This enzyme is a member of the long form (HisG L ) ATP-PRT and is allosterically inhibited by histidine, which binds to a remote regulatory domain, and competitively inhibited by AMP. In the crystalline form, CjeATP-PRT was found to adopt two distinctly different hexameric conformations, with an open homohexameric structure observed in the presence of substrate ATP, and a more compact closed form present when inhibitor histidine is bound. CjeATP-PRT was observed to adopt only a hexameric quaternary structure in solution, contradicting previous hypotheses favoring an allosteric mechanism driven by an oligomer equilibrium.Abbreviations: ATP-PRT, adenosine triphosphate phosphoribosyltransferase; BTP, 1,3-bis[tris(hydroxymethyl)methylamino]propane; CjeATP-PRT, ATP-PRT from Campylobacter jejuni; EcoATP-PRT, Escherichia coli ATP-PRT; His, l-histidine; ITC, isothermal titration calorimetry; MtuATP-PRT, Mycobacterium tuberculosis ATP-PRT; PDB, Protein Data Bank; PR-ATP, phosphoribosyl ATP; PRPP, phosphoribosyl pyrophosphate; PRT, phosphoribosyltransferase; RMSD, root-mean-square difference; SenATP-PRT, Salmonella enterica subsp. enterica Typhimurium ATP-PRT Additional Supporting Information may be found in the online version of this article.Significance Statement: ATP-phosphoribosyltransferase catalyzes the first dedicated step in the biosynthesis of the essential amino acid histidine in microorganisms. We report the functional characterization of this enzyme from human pathogen Campylobacter jejuni. The enzyme is inhibited by histidine, allowing for tuned production of histidine in response to cellular demands. Our results reveal how the enzyme structure becomes compressed when histidine binds and exposes the molecular details of how this enzyme performs its function. Instead, this study supports the conclusion that the ATP-PRT long form hexamer is the active species; the tightening of this structure in response to remote histidine binding results in an inhibited enzyme.

show abstract

Studies on the quaternary structure of the first enzyme for histidine biosynthesis

Cited by 17 publications

References 15 publications

Crystal Structure of ATP Phosphoribosyltransferase fromMycobacterium tuberculosis

Crystal Structure of ATP Phosphoribosyltransferase fromMycobacterium tuberculosis

Fluorescence studies of phosphoribosyladenosine triphosphate synthetase of Escherichia coli

Campylobacter jejuni adenosine triphosphate phosphoribosyltransferase is an active hexamer that is allosterically controlled by the twisting of a regulatory tail

Contact Info

Product

Resources

About