Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
PLoS One ; 9(6): e97198, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24937088

RESUMO

Human rhinovirus strains differ greatly in their virulence, and this has been correlated with the differing substrate specificity of the respective 2A protease (2Apro). Rhinoviruses use their 2Apro to cleave a spectrum of cellular proteins important to virus replication and anti-host activities. These enzymes share a chymotrypsin-like fold stabilized by a tetra-coordinated zinc ion. The catalytic triad consists of conserved Cys (C105), His (H34), and Asp (D18) residues. We used a semi-automated NMR protocol developed at NMRFAM to determine the solution structure of 2Apro (C105A variant) from an isolate of the clinically important rhinovirus C species (RV-C). The backbone of C2 2Apro superimposed closely (1.41-1.81 Å rmsd) with those of orthologs from RV-A2, coxsackie B4 (CB4), and enterovirus 71 (EV71) having sequence identities between 40% and 60%. Comparison of the structures suggest that the differential functional properties of C2 2Apro stem from its unique surface charge, high proportion of surface aromatics, and sequence surrounding the di-tyrosine flap.


Assuntos
Cisteína Endopeptidases/química , Rhinovirus/enzimologia , Proteínas Virais/química , Sequência de Aminoácidos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Estrutura Terciária de Proteína
2.
J Am Chem Soc ; 135(22): 8117-20, 2013 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-23682711

RESUMO

Escherichia coli [2Fe-2S]-ferredoxin (Fdx) is encoded by the isc operon along with other proteins involved in the 'house-keeping' mechanism of iron-sulfur cluster biogenesis. Although it has been proposed that Fdx supplies electrons to reduce sulfane sulfur (S(0)) produced by the cysteine desulfurase (IscS) to sulfide (S(2-)) as required for the assembly of Fe-S clusters on the scaffold protein (IscU), direct experimental evidence for the role of Fdx has been lacking. Here, we show that Fdx (in either oxidation state) interacts directly with IscS. The interaction face on Fdx was found to include residues close to its Fe-S cluster. In addition, C328 of IscS, the residue known to pick up sulfur from the active site of IscS and deliver it to the Cys residues of IscU, formed a disulfide bridge with Fdx in the presence of an oxidizing agent. Electrons from reduced Fdx were transferred to IscS only in the presence of l-cysteine, but not to the C328S variant. We found that Fdx, IscU, and CyaY (the bacterial frataxin) compete for overlapping binding sites on IscS. This mutual exclusion explains the mechanism by which CyaY inhibits Fe-S cluster biogenesis. These results (1) show that reduced Fdx supplies one electron to the IscS complex as S(0) is produced by the enzymatic conversion of Cys to Ala and (2) explain the role of Fdx as a member of the isc operon.


Assuntos
Liases de Carbono-Enxofre/metabolismo , Elétrons , Ferredoxinas/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Ferro/metabolismo , Enxofre/metabolismo , Sítios de Ligação , Liases de Carbono-Enxofre/química , Cristalografia por Raios X , Escherichia coli/química , Escherichia coli/metabolismo , Ferredoxinas/química , Ferro/química , Proteínas de Ligação ao Ferro/química , Modelos Moleculares , Enxofre/química , Frataxina
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...