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.
J Am Chem Soc ; 141(15): 6136-6140, 2019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-30921515

RESUMO

While cryo-EM is revolutionizing structural biology, its impact on enzymology is yet to be fully demonstrated. The ketol-acid reductoisomerase (KARI) catalyzes conversion of (2 S)-acetolactate or (2 S)-aceto-2-hydroxybutyrate to 2,3-dihydroxy-3-alkylbutyrate. We found that KARI from archaea Sulfolobus solfataricus (Sso-KARI) is unusual in being a dodecamer, bispecific to NADH and NADPH, and losing activity above pH 7.8. While crystals were obtainable only at pH 8.5, cryo-EM structures were solved at pH 7.5 and 8.5 for Sso-KARI:2Mg2+. The results showed that the distances of the two catalytic Mg2+ ions are lengthened in both structures at pH 8.5. We next solved cryo-EM structures of two Sso-KARI complexes, with NADH+inhibitor and NADPH+inhibitor at pH 7.5, which indicate that the bispecificity can be attributed to a unique asparagine at the cofactor binding loop. Unexpectedly, Sso-KARI also differs from other KARI enzymes in lacking "induced-fit", reflecting structural rigidity. Thus, cryo-EM is powerful for structural and mechanistic enzymology.


Assuntos
Álcoois/metabolismo , Archaea/enzimologia , Cetol-Ácido Redutoisomerase/química , Cetonas/metabolismo , Álcoois/química , Cristalografia por Raios X , Concentração de Íons de Hidrogênio , Cetol-Ácido Redutoisomerase/metabolismo , Cetonas/química , Modelos Moleculares , Conformação Molecular
2.
Acta Crystallogr F Struct Biol Commun ; 75(Pt 2): 73-79, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30713157

RESUMO

Programmed cell death 5 (PDCD5) is a vital signaling protein in the apoptosis pathway in eukaryotes. It is known that there are two dissociated N-terminal regions and a triple-helix core in eukaryotic PDCD5. Structural and functional studies of PDCD5 from hyperthermophilic archaea have been limited to date. Here, the PDCD5 homolog Sso0352 (SsoPDCD5) was identified in Sulfolobus solfataricus, the SsoPDCD5 protein was expressed and crystallized, and the phase was identified by single-wavelength anomalous diffraction. The native SsoPDCD5 crystal belonged to space group C2 and diffracted to 1.49 Šresolution. This is the first crystal structure of a PDCD5 homolog to be solved. SsoPDCD5 shares a similar triple-helix bundle with eukaryotic PDCD5 but has a long α-helix in the N-terminus. A structural search and biochemical data suggest that SsoPDCD5 may function as a DNA-binding protein.


Assuntos
Proteínas Reguladoras de Apoptose/química , Proteínas de Neoplasias/química , Sulfolobus solfataricus/enzimologia , Sequência de Aminoácidos , Proteínas Reguladoras de Apoptose/isolamento & purificação , Proteínas Reguladoras de Apoptose/metabolismo , Cristalização , Cristalografia por Raios X , Humanos , Modelos Moleculares , Proteínas de Neoplasias/isolamento & purificação , Proteínas de Neoplasias/metabolismo , Ligação Proteica , Conformação Proteica , Homologia de Sequência
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...