Alpha4 protein as a common regulator of type 2A-related serine/threonine protein phosphatases

The catalytic activity of the C subunit of serine/threonine phosphatase 2A is regulated by the association with A (PR65) and B subunits. It has been reported that the alpha4 protein, a yeast homolog of the Tap42 protein, binds the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases such as protein phosphatase 4 and protein phosphatase 6. In the present study, we showed that alpha4 binds these three phosphatases and the association of alpha4 reduces the activities of these phosphatases in vitro. In contrast, PR65 binds to the C subunit of serine/threonine phosphatase 2A but not to protein phosphatase 4 and protein phosphatase 6. These results suggest that the alpha4 protein is a common regulator of the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases.     

Novel (CA)n marker DXYS241 on the nonrecombinant part of the human Y chromosome

The origin of modern humans can be traced by comparing polymorphic sites in either mitochondria or genomic sequences between humans and other primates. The human Y chromosome has both a non-recombining region and X-Y homologous pseudo-autosomal regions. In the nonrecombining region events during evolution can be directly detected. At least a part of homology between Xq21 and Yp11 is a result of rather recent translocations from the X chromosome to the Y chromosome. DNA markers residing in the nonrecombining region of the human Y chromosome are potentially useful in tracing male-specific gene flow in human evolution. However, the number of available markers in the region is limited. Here, we report a novel X-Y homologous (CA)n repeat locus in the nonrecombining region of the Y chromosome. This marker, DXYS241, has several interesting features. Y- and X-chromosome alleles are distinguishable because the Y-chromosome alleles are shorter than the X-chromosome alleles most of the time. We developed 2 primer sets for specific examination of Y- and X-chromosome alleles. The marker should be useful in establishing relationships between populations based on patrilineal gene flow. Sequences homologous to DXYS241 are also found on the X chromosome of primates. Four events during primate evolution that led to the modern human Y chromosome were identified.     

Salt-inducible multidrug efflux pump protein in the moderately halophilic bacterium Chromohalobacter sp

It has been known that halophilic bacteria often show natural resistance to antibiotics, dyes, and toxic metal ions, but the mechanism and regulation of this resistance have remained unexplained. We have addressed this question by identifying the gene responsible for multidrug resistance. A spontaneous ofloxacin-resistant mutant derived from the moderately halophilic bacterium Chromohalobacter sp. strain 160 showed a two- to fourfold increased resistance to structurally diverse compounds, such as tetracycline, cefsulodin, chloramphenicol, and ethidium bromide (EtBr), and tolerance to organic solvents, e.g., hexane and heptane. The mutant produced an elevated level of the 58-kDa outer membrane protein. This mutant (160R) accumulated about one-third the level of EtBr that the parent cells did. An uncoupler, carbonyl cyanide m-chlorophenylhydrazone, caused a severalfold increase in the intracellular accumulation of EtBr, with the wild-type and mutant cells accumulating nearly equal amounts. The hrdC gene encoding the 58-kDa outer membrane protein has been cloned. Disruption of this gene rendered the cells hypersusceptible to antibiotics and EtBr and led to a high level of accumulation of intracellular EtBr. The primary structure of HrdC has a weak similarity to that of Escherichia coli TolC. Interestingly, both drug resistance and the expression of HrdC were markedly increased in the presence of a high salt concentration in the growth medium, but this was not observed in hrdC-disrupted cells. These results indicate that HrdC is the outer membrane component of the putative efflux pump assembly and that it plays a major role in the observed induction of drug resistance by salt in this bacterium.     

Production of <Emphasis Type="SmallCaps">l</Emphasis>-lactic acid from a mixture of xylose and glucose by co-cultivation of lactic acid bacteria

The production of optically pure lactic acid in a high yield from xylose or a mixture of xylose and glucose, which is a model hydrolysate of lignocellulose, is described. In a single cultivation, Enterococcus casseliflavus produced 38 g/l of lactic acid with an optical purity of 96% enantiomeric excess (ee) and 6.4 g/l of acetic acid from 50 g/l of xylose when MRS medium was used. When a mixture of 50 g/l of xylose and 100 g/l of glucose was used as the carbon source in a cultivation of E. casseliflavus alone, glucose was converted to lactic acid in the early phase of the cultivation but xylose was hardly consumed. In a co-cultivation where E. casseliflavus and Lactobacillus casei specific for glucose were simultaneously inoculated, little or no lactic acid was produced after the glucose was almost consumed. A co-cultivation with two-stage inoculation (in which E. casseliflavus was added at a cultivation time of 40 h after L. casei cells were inoculated) resulted in complete consumption of 50 g/l of xylose and 100 g/l of glucose. In the co-cultivation, 95 g/l of lactic acid with a high optical purity of 96% ee was obtained at 192 h. Such a co-cultivation using two microorganisms specific for each sugar is considered to be one promising cultivation technique for the efficient production of lactic acid from a sugar mixture derived from lignocellulose.     

Expression and purification of cytokine receptor homology domain of human granulocyte-colony-stimulating factor receptor fusion protein in Escherichia coli

Direct expression of the cytokine receptor homology (CRH) domain of granulocyte-colony-stimulating factor (G-CSF) receptor is lethal to Escherichia coli. For the efficient and stable production of an active CRH domain in E. coli, we fused the CRH domain with different proteins, such as maltose-binding protein (MalE), glutathione S-transferase, and thioredoxin (Trx). Among these, Trx appeared to be the best in terms of the protein expression level, purification efficiency by affinity chromatography, and binding activity to its ligand, G-CSF. The yield of active Trx-CRH fusion protein increased about 200-fold compared to that of previously reported MalE-CRH fusion.     

The relationships among exercise behavior, functional ADL, and psychological health in the elderly

The purpose of this study was to examine the relationships among exercise behavior, the ability to live independently as assessed by functional activities of daily living (ADL), and psychological health as measured by the Philadelphia Geriatric Center morale scale, using data from 202 elderly residents aged 70 and living in their own home. The main results obtained from the analysis were as follows. 1. Exercise behavior had a significant effect on functional ADL. In particular, subjects who had been exercising regularly for 6 months or longer had higher functional ADL than subjects who did not exercise. 2. For psychological health, the functional ADL level was statistically significant, whereas exercise behavior was not. 3. Multiple regression analysis showed a positive and significant association between psychological health and functional ADL, but not between psychological health and exercise behavior, gender or family type. The results of this study demonstrated that elderly people's efforts to maintain and enhance their psychological health play important roles in their ability to live independently, and that regular exercise is necessary to an elderly person's ability to live independently.     

Secretion of Escherichia coli DsbA and DsbC proteins from Brevibacillus choshinensis: stimulation of human epidermal growth factor production

DsbA and DsbC, members of the thioredoxin super-family of redox proteins, which are expressed in the periplasmic space of Escherichia coli, were cloned into and successfully secreted from Brevibacillus choshinensis at 100 g ml^–1. Both proteins were active in exchanging disulfide bonds of bovine insulin in vitro. Furthermore, DsbA secreted by B. choshinensis promoted the conversion of non-native human epidermal growth factor to the native form.