Orotidine 5'-monophosphate decarboxylase: the operation of active site chains within and across protein subunits

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dc.creatorTiago Antônio da Silva Brandão
dc.creatorJohn P. Richard
dc.date.accessioned2023-09-29T12:01:44Z
dc.date.accessioned2025-09-08T23:59:39Z
dc.date.available2023-09-29T12:01:44Z
dc.date.issued2020
dc.format.mimetypepdf
dc.identifier.doihttps://doi.org/10.1021/acs.biochem.0c00241
dc.identifier.issn1520-4995
dc.identifier.urihttps://hdl.handle.net/1843/59025
dc.languageeng
dc.publisherUniversidade Federal de Minas Gerais
dc.relation.ispartofBiochemistry
dc.rightsAcesso Aberto
dc.subjectMonomeros
dc.subjectProteinas
dc.subjectAnálise enzimática
dc.subjectMecanismos de reações orgânicas
dc.subjectReações químicas
dc.subjectBioquímica
dc.subject.otherMonomers
dc.subject.otherOligomers
dc.subject.otherOrganic reactions
dc.subject.otherPeptides and proteins
dc.subject.otherSurface interactions
dc.titleOrotidine 5'-monophosphate decarboxylase: the operation of active site chains within and across protein subunits
dc.typeArtigo de periódico
local.citation.epage2040
local.citation.issue21
local.citation.spage2032
local.citation.volume59
local.description.resumoThe D37 and T100′ side chains of orotidine 5′-monophosphate decarboxylase (OMPDC) interact with the C-3′ and C-2′ ribosyl hydroxyl groups, respectively, of the bound substrate. We compare the intra-subunit interactions of D37 with the inter-subunit interactions of T100′ by determining the effects of the D37G, D37A, T100′G, and T100′A substitutions on the following: (a) kcat and kcat/Km values for the OMPDC-catalyzed decarboxylations of OMP and 5-fluoroorotidine 5′-monophosphate (FOMP) and (b) the stability of dimeric OMPDC relative to the monomer. The D37G and T100′A substitutions resulted in 2 kcal mol–1 increases in ΔG† for kcat/Km for the decarboxylation of OMP, while the D37A and T100′G substitutions resulted in larger 4 and 5 kcal mol–1 increases, respectively, in ΔG†. The D37G and T100′A substitutions both resulted in smaller 2 kcal mol–1 decreases in ΔG† for the decarboxylation of FOMP compared to that of OMP. These results show that the D37G and T100′A substitutions affect the barrier to the chemical decarboxylation step while the D37A and T100′G substitutions also affect the barrier to a slow, ligand-driven enzyme conformational change. Substrate binding induces the movement of an α-helix (G′98–S′106) toward the substrate C-2′ ribosyl hydroxy bound at the main subunit. The T100′G substitution destabilizes the enzyme dimer by 3.5 kcal mol–1 compared to the monomer, which is consistent with the known destabilization of α-helices by the internal Gly side chains [Serrano, L., et al. (1992) Nature, 356, 453–455]. We propose that the T100′G substitution weakens the α-helical contacts at the dimer interface, which results in a decrease in the dimer stability and an increase in the barrier to the ligand-driven conformational change.
local.identifier.orcidhttps://orcid.org/0000-0002-7783-3014
local.identifier.orcidhttps://orcid.org/0000-0002-0440-2387
local.publisher.countryBrasil
local.publisher.departmentICX - DEPARTAMENTO DE QUÍMICA
local.publisher.initialsUFMG
local.url.externahttps://pubs.acs.org/doi/10.1021/acs.biochem.0c00241

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