RESUMO
Iron-sulfur (Fe-S) clusters are ubiquitous and are necessary to sustain basic life processes. The intracellular Fe-S clusters do not form spontaneously and many proteins are required for their biosynthesis and delivery. The bacterial P-loop NTPase family protein ApbC participates in Fe-S cluster assembly and transfers the cluster into apoproteins, with the Walker A motif and CxxC motif being essential for functionality of ApbC in Fe-S protein biogenesis. However, the structural basis underlying the ApbC activity and the motifs' role remains unclear. Here, we report the crystal structure of Escherichia coli ApbC at 2.8 Å resolution. The dimeric structure is in a W shape and the active site is located in the 2-fold center. The function of the motifs can be annotated by structural analyses. ApbC has an additional N-terminal domain that differs from other P-loop NTPases, possibly conferring its inherent specificity in vivo.
Assuntos
Proteínas de Escherichia coli , Escherichia coli , Proteínas Ferro-Enxofre , Sequência de Aminoácidos , Domínio Catalítico , Cristalografia por Raios X , Escherichia coli/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas Ferro-Enxofre/química , Proteínas Ferro-Enxofre/metabolismo , Proteínas Ferro-Enxofre/genética , Modelos Moleculares , Conformação Proteica , Multimerização ProteicaRESUMO
The chemical constituents of Draconis Sanguis were preliminarily studied by macroporous resin, silica gel, dextran gel, and high-performance liquid chromatography. One retro-dihydrochalcone, four flavonoids, and one stilbene were isolated. Their chemical structures were identified as 4-hydroxy-2,6-dimethoxy-3-methyldihydrochalcone(1), 4'-hydroxy-5,7-dimethoxy-8-methylflavan(2), 7-hydroxy-4',5-dimethoxyflavan(3),(2S)-7-hydroxy-5-methoxy-6-methylflavan(4),(2S)-7-hydroxy-5-methoxyflavan(5), and pterostilbene(6) by modern spectroscopy, physicochemical properties, and literature comparison. Compound 1 was a new compound. Compounds 2 and 6 were first found in the Arecaceae family. Compound 5 had the potential to prevent and treat diabetic kidney disease.
Assuntos
Arecaceae , Diabetes Mellitus , Nefropatias Diabéticas , Medicamentos de Ervas Chinesas , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/prevenção & controle , Flavonoides/análise , Medicamentos de Ervas Chinesas/química , Cromatografia Líquida de Alta Pressão/métodosRESUMO
Nitrite and microplastics (MPs) are environmental pollutants that threaten intestinal integrity and affect immune function of shrimp. In this study, the shrimp Litopenaeus vannamei were exposed to the individual and combined stress of nitrite and microplastics for 14 days, and the changes of intestinal histology and physiological functions were investigated. After single and combined stress, affectations occurred in intestinal tissue; the antioxidant enzyme activities (MDA, H2O2, CAT increased) and gene expression levels (CAT, SOD, GPx, HSP70 up-regulated) changed. The expression levels of detoxification genes (CYP450, UGT down-regulated, GST up-regulated), apoptosis genes (CASP-3 up-regulated) and endoplasmic reticulum stress genes (Bip, GRP94 down-regulated) changed. Furthermore, the stress also increased intestinal microbial diversity, causing bacterial composition variation, especially beneficial bacteria and pathogenic bacteria. These results suggested that nitrite and microplastics stress had adverse effects on the intestinal health of L. vannamei by affecting intestinal tissue morphology, immune response and microbial community.