Three different binding sites of Cks1 are required for p27-ubiquitin ligation

Previous studies have shown that the cyclin-dependent kinase (Cdk) inhibitor p27(Kip1) is targeted for degradation by an SCF(Skp2) ubiquitin ligase complex and that this process requires Cks1, a member of the highly conserved Suc1/Cks family of cell cycle regulatory proteins. All proteins of this family have Cdk-binding and anion-binding sites, but only mammalian Cks1 binds to Skp2 and promotes the association of Skp2 with p27 phosphorylated on Thr-187. The molecular mechanisms by which Cks1 promotes the interaction of the Skp2 ubiquitin ligase subunit to p27 remained obscure. Here we show that the Skp2-binding site of Cks1 is located on a region including the alpha2- and alpha1-helices and their immediate vicinity, well separated from the other two binding sites. All three binding sites of Cks1 are required for p27-ubiquitin ligation and for the association of Skp2 with Cdk-bound, Thr-187-phosphorylated p27. Cks1 and Skp2 mutually promote the binding of each other to a peptide similar to the 19 C-terminal amino acids of p27 containing phosphorylated Thr-187. This latter process requires the Skp2- and anion-binding sites of Cks1, but not its Cdk-binding site. It is proposed that the Skp2-Cks1 complex binds initially to the C-terminal region of phosphorylated p27 in a process promoted by the anion-binding site of Cks1. The interaction of Skp2 with the substrate is further strengthened by the association of the Cdk-binding site of Cks1 with Cdk2/cyclin E, to which phosphorylated p27 is bound.     

A new class of biflavonoids: 2'-hydroxygenistein dimers from the roots of white lupin

Two novel isoflavonoid dimers presumably originating from 2'-hydroxygenistein, 5,7,4'-trihydroxycoumaranochroman-4-one-(3-->5"')-5",7",2"'4"'- tetrahydroxyisoflavone (1, lupinalbisone A) and 5,7,4'-trihydroxycoumaranochroman-4-one-(3-6")-5",7",2"',4"'-te trahydroxyisoflavone (2, lupinalbisone B) were isolated from the roots of Lupinus albus L., and their structures involving relative stereochemistry were elucidated by spectroscopic methods. Using horse radish peroxidase and 2'-hydroxygenistein (3) as the substrate revealed the formation of these dimers together with 5,7,4'-trihydroxycoumaronochromone (4, lupinalbin A). Dimerization of 3 caused a remarkable increase of antifungal activity.     

Feeding strategy design for recombinant human growth hormone production by Bacillus subtilis

Bioprocess and Biosystems Engineering - Defined and semi-defined medium-based feeding strategies were developed to enhance recombinant human growth hormone (rhGH) production by Bacillus subtilis...     

Low Incidence of Renal Dysfunction among HIV-Infected Patients on a Tenofovir-Based First Line Antiretroviral Treatment Regimen in Myanmar

Background

Since 2004, Médecins Sans Frontières-Switzerland has provided treatment and care for people living with HIV in Dawei, Myanmar. Renal function is routinely monitored in patients on tenofovir (TDF)-based antiretroviral treatment (ART), and this provides an opportunity to measure incidence and risk factors for renal dysfunction.

Methods

We used routinely collected program data on all patients aged ≥15 years starting first-line TDF-based ART between January 2012 and December 2013. Creatinine clearance (CrCl) was assessed at base line and six-monthly, with renal dysfunction defined as CrCl < 50ml/min/1.73m². We calculated incidence of renal dysfunction and used Cox regression analysis to identify associated risk factors.

Results

There were 1391 patients, of whom 1372 had normal renal function at baseline. Of these, 86 (6.3%) developed renal dysfunction during a median time of follow-up 1.14 years with an incidence rate of 5.4 per 100 person-years: 78 had CrCl between 30–50ml/min/1.73m² and were maintained on TDF–based ART, but 5 were changed to another regimen: 4 because of CrCl <30ml/min/1.73m². Risk factors for renal dysfunction included age ≥45 years, diagnosed diabetes, underlying renal disease, underweight and CD4 count <200cells/mm³. There were 19 patients with baseline renal dysfunction and all continued on TDF-based ART: CrCl stayed between 30–49 ml/min/1.73m² in five patients while the remainder regained normal renal function.

Conclusions

In a resource-poor country like Myanmar, the low incidence of renal toxicity in our patient cohort suggests that routine assessment of CrCl may not be needed and could be targeted to high risk groups if resources permit.     

Will Limited Land, Water, and Energy Control Human Population Numbers in the Future?

Nearly 60% of the world’s human population is malnourished and the numbers are growing. Shortages of basic foods related to decreases in per capita cropland, water, and fossil energy resources contribute to spreading malnutrition and other diseases. The suggestion is that in the future only a smaller number of people will have access to adequate nourishment. In about 100 years, when it is reported that the planet will run out of fossil energy, we suggest that a world population of about two billion might be sustainable if it relies on renewable energy technologies and also reduces per capita use of the earth’s natural resources.     

Coexistent mosaic monosomy 21 and fragile X syndrome in a mentally retarded male patient

Fragile X syndrome (FXS) is a well-recognized mental retardation syndrome with characteristic facial features and behavioural phenotype. Monosomy 21 is a rare cytogenetic aberration for which clinical features were incompletely defined since full monosomy 21 is incompatible with life. A 5-year-old male patient with FXS and low-grade mosaicism for full monosomy 21 (46,XY[96%]/45,XY,-21[4%]) is presented. He had lack of speech and severely impaired social skills, hyperactivity, stereotypical hand movements, a special interest towards moving colourful items and a short attention span for other objects around. He had macrocephaly, a rather long face, prominent occiput and prominent midface, retrognathia, down-slanting palpebral fissures, hypertelorism and cup-shaped, posteriorly rotated and low-set ears. Full monosomy in the aberrant cell line was proven by whole chromosome painting. FXS was previously reported to accompany sex chromosome aneuploidies; however, to the best of our knowledge, the present patient is the first FXS patient with an aberration involving autosomes. He contributes to the current knowledge on monosomy 21 phenotype, having dysmorphic facial findings despite the concurrent phenotypic expression of the FXS. As a last conclusion, cytogenetic analysis must be done to all mentally retarded patients with minor dysmorphic features.     

Development of a prototype wound dressing technology which can detect and report colonization by pathogenic bacteria

A new methodology for detecting the microbiological state of a wound dressing in terms of its colonization with pathogenic bacteria such as Staphylococcus aureus or Pseudomonas aeruginosa has been developed. Here we report how stabilized lipid vesicles containing self-quenched carboxyfluorescein dye are sensitive to lysis only by toxins/virulence factors from P. aeruginosa and S. aureus but not by a non-toxic Escherichia coli species. The development of the stabilized vesicles is discussed and their response to detergent (triton), bacterial toxin (α-hemolysin) and lipases (phospholipase A₂). Finally, fabrics with stabilized vesicles attached via plasma deposited maleic anhydride coupling are shown visibly responding to S. aureus (MSSA 476) and P. aeruginosa (PAO1) but not E. coli DH5α in a prototype dressing.     

犬细小病毒VP2基因在枯草芽孢杆菌中的表达及鉴定

从犬细小病毒/犬瘟热二联苗中提取CPV基因组,根据GenBank发表的CPV-VP2基因序列设计一对引物,对VP2基因进行PCR扩增,并克隆至TA Cloning(R) Kit Dual Promoter( pCRⅡ),获得克隆栽体pCRⅡ-VP2.将重组质粒亚克隆到枯草芽孢杆菌表达载体pHT43上,获得重组表达栽体pHT43-VP2.经双酶切鉴定及序列比对分析后,将pHT43-VP2载体转化入枯草芽孢杆菌WB600中进行诱导表达,产物使用PAGE胶蛋白回收法纯化.结果表明,在69 kD处存在目的蛋白,ELISA检测发现,纯化后的目的蛋白与阳性血清存在特异性反应.