No abstract

Hydrogenases are the key enzymes for the biological hydrogen production, which can be classified as H(2)-uptake hydrogenase and H(2)-production hydrogenase. The genes encoding a membrane-bound [NiFe]-hydrogenase (MBH), which is mainly responsible for hydrogen uptake, from the photosynthetic bacterium Allochromatium vinosum was cloned and sequenced. It consist of two structural genes (hydS, hydL) and two intergenic genes (isp1, isp2), which are therefore organized as hydS-isp1-isp2-hydL. This is different from the arrangement of other typical hydrogenase gene clusters. A deletion mutant-strain PhihydSL, lacking isp1, isp2, partial hydS and hydL genes, was constructed by marker-exchange mutagenesis. Under dark fermentative conditions, the hydrogen production yield by this mutant increased by 62%. The result suggests that the disruption of MBH could greatly improve the hydrogen production in the cells by decreasing the hydrogen uptake.

K48-linked ubiquitination determines antigen degradation and plays vital roles in the process of cross-presentation of bone marrow precursor cell (BMPC)-derived dendritic cells (DCs). Although previous studies revealed that K48 and K27-linked ubiquitination regulates innate immunity, the exact roles of K48 and K27-linked ubiquitination in cross-presentation and BMPC-based adaptive immunity are still uncertain. In this study, we investigated the effects of K48-and K27-mutant ubiquitin (Ub) on BMPCbased adaptive immune response by observing the effects of MG132, Ub deficiency, and K48/K27-mutant Ub on cross-presentation, T cell proliferation, IFN-γ secretion, BMPC-based CTL priming, and thereby the efficiency of cytolytic capacity of BMPCactivate T cells. We demonstrated that MG132, Ub deficiency, and K48-mutant Ub impair cross-presentation, T cell proliferation, IFN-γ secretion, BMPC-based CTL priming, and the cytolytic capacity of BMPC-activated T cells. Moreover, although K27only Ub decreases cross-presentation, the replenishment of K27-mutant Ub restores Ub deficiency impaireds the abilities of T cell proliferation, IFN-γ secretion, CTL priming, and the cytolytic capacity of BMPC-activated T cells. Thus, these data suggest that K48-and K27-linked ubiquitination contributes to BMPC-mediated adaptive immune response by affecting BMPC cross-presentation and the cytolytic capacity by up-regulating both perforin and granzyme B in BMPC-activated T cells. K48-and K27-mutant Ub might have potential clinical therapeutic function in adaptive immune response-associated diseases.