ATP-dependent chromatin-remodeling complexes contribute to the proper temporal and spatial patterns of gene expression in mammalian embryos and therefore play important roles in a number of developmental processes. SWI/SNF-like chromatin-remodeling complexes use one of two different ATPases as their catalytic subunit: brahma (BRM, also known as SMARCA2) and brahma-related gene 1 (BRG1, also known as SMARCA4). We have conditionally deleted a floxed Brg1 allele with a Tie2-Cre transgene, which is expressed in developing hematopoietic and endothelial cells. Brg1(fl/fl):Tie2-Cre(+) embryos die at midgestation from anemia, as mutant primitive erythrocytes fail to transcribe embryonic alpha- and beta-globins, and subsequently undergo apoptosis. Additionally, vascular remodeling of the extraembryonic yolk sac is abnormal in Brg1(fl/fl):Tie2-Cre(+) embryos. Importantly, Brm deficiency does not exacerbate the erythropoietic or vascular abnormalities found in Brg1(fl/fl):Tie2-Cre(+) embryos, implying that Brg1-containing SWI/SNF-like complexes, rather than Brm-containing complexes, play a crucial role in primitive erythropoiesis and in early vascular development. 相似文献
Co(III) has been stoichiometrically incorporated into jack bean concanavalin A. The Co(III) protein still possesses a binding site for an additional divalent transition metal ion which together with Ca(II) can induce the sugar binding ability. No H2O2 oxidation of Co(II) occurs with demetallized concanavalin A activated with Ca(II) and Co(II) unless Co(II) is present in a stoichiometric excess. Evidence is presented to indicate that kinetically stable Co(III) is bound to a completely different location than the thermodynamically stable Co(II) protein site. 相似文献
Plant biomass, once reduced to its composite sugars, can be converted to fuel substitutes. One means of overcoming the recalcitrance of lignocellulose is pretreatment followed by enzymatic hydrolysis. However, currently available commercial enzyme cocktails are inhibited in the presence of residual pretreatment chemicals. Recent studies have identified a number of cellulolytic enzymes from bacteria that are tolerant to pretreatment chemicals such as ionic liquids. The challenge now is generation of these enzymes in copious amounts, an arena where fungal organisms such as Aspergillus niger have proven efficient. Fungal host strains still need to be engineered to increase production titers of heterologous protein over native enzymes, which has been a difficult task. Here, we developed a forward genetics screen coupled with whole-genome resequencing to identify specific lesions responsible for a protein hyper-production phenotype in A. niger. This strategy successfully identified novel targets, including a low-affinity glucose transporter, MstC, whose deletion significantly improved secretion of recombinant proteins driven by a glucoamylase promoter.
Janus kinases comprise carboxyterminal kinase, pseudokinase, SH2-like, and N-terminal FERM domains. We identified three patient-derived mutations in the FERM domain of Jak3 and investigated the functional consequences of these mutations. These mutations inhibited receptor binding and also abrogated kinase activity, suggesting interactions between the FERM and kinase domains. In fact, the domains were found to physically associate, and coexpression of the FERM domain enhanced activity of the isolated kinase domain. Conversely, staurosporine, which alters kinase domain structure, disrupted receptor binding, even though the catalytic activity of Jak3 is dispensable for receptor binding. Thus, the Jak FERM domain appears to have two critical functions: receptor interaction and maintenance of kinase integrity. 相似文献
Several reports have shown that urotensin 2 (UTS2) and its receptor (UTS2R) are involved in glucose metabolism and insulin resistance, which lead to development of type 2 diabetes mellitus (T2DM) in humans. In the present study, we annotated both bovine UTS2 and UTS2R genes and identified 5 single nucleotide polymorphisms (SNPs) for the former gene and 14 mutations for the latter gene. Four mutations were genotyped on a Wagyu x Limousin reference population, including 6 F1 bulls, 113 F1 dams and ~250 F2 progeny. Among 12 phenotypes related to fat deposition and fatty acid composition, we observed that the UTS2 gene was significantly associated with the amount of skeletal saturated fatty acids, while its receptor (UTS2R) gene had significant effects on amounts of saturated and monounsaturated fatty acids, Δ9 desaturase activity for converting 16:0 into 16:1, muscle fat (marbling) score and Longissimus Dorsi muscle area. However, in this population, these markers were not associated with subcutaneous fat depth or percent kidney, pelvic and heart fat. We also found that mutations in the promoter regions altered the promoter activities in both genes and coding SNPs might affect the mRNA stability in the UTS2R gene. Overall, our present study provides the first evidence that both UTS2 and UTS2R genes regulate skeletal muscle fat accumulation and fatty acid metabolism, thus indicating their potential pathological functions related to obesity and T2DM in humans. 相似文献