Functional expression and purification of bovine enterokinase light chain in recombinant Escherichia coli

Enterokinase (EC 3.4.21.9) is a serine proteinase of the intestinal brush border that exhibits specificity for the sequence (Asp)(4)-Lys and converts trypsinogen into its active form, trypsin. A codon optimized sequence coding light chain (catalytic subunit) of bovine enterokinase gene (sBEKLC) was synthesized, and it was fused with DsbA to construct the expression vector (pET39-sBEKLC). Then, the plasmid was transformed into E. coli BL21 (DE3) for expression. Under optimal conditions, the volumetric productivity of fusion protein reached 151.2 mg L(-1), i.e., 80.6 mg sBEKLC L(-1). The cold osmotic shock technique was successfully used to extract sBEKLC from periplasmic space, and nickel affinity chromatography was employed to obtain mature sBEKLC. Finally, about 6.8 mg of bioactive sBEKLC was purified from 1 liter fermentation broth and could be used to cleave one tested fusion protein with an inter-domain enteropeptidase recognition site. This work will be helpful for large-scale production of this increasingly demanded enterokinase.     

Home range and habitat use of male Reeves’s pheasant (Syrmaticus reevesii) during winter in Dongzhai National Nature Reserve, Henan Province, China

Home range and habitat use of male Reeves’s pheasant (Syrmaticus reevesii) were studied during winter of 2001∼2002 and 2002∼2003 in the Dongzhai National Nature Reserve, Henan Province. Results from five individuals of Reeves’s pheasant with over 30 relocations, indicated that the average size of home range was 10.03 ± 1.17 hm² by Minimum Convex Polygon method, 8.60 ± 0.35 hm² by 90% Harmonic Mean Transformation method, and 9.50 ± 1.90 hm² by 95% Fixed Kernel method. It was observed that the winter range is smaller than that in the breeding season. The mean core area of the home range was found to be 1.88 ± 0.37 hm². Although the habitat composition of the core area varied greatly for individuals, a large part of the habitats used were composed of confier and broadleaf mixed forests, masson pine forests, fir forests, and shrubs. Habitat use within the study area was non-random, while habitats within home ranges were randomly used. Habitat use was dictated by tree diameter at breast height, shrub height and coverage at 2.0 m. The proximity between forests and shrubs were also found to be important in providing refuge for the birds during winter. Recommendations for conservation management include protecting the existing habitats in Dongzhai National Nature Reserve, increasing suitable habitat for Reeves’s Pheasant through artificial plantations (e.g. firs), and restoring some parts of the large shrub area into forests. __________ Translated from Biodiversity Science, 2005, 13 (5) [译自: 生物多样性, 2005,13(5)]     

Protein kinase A RII-like (R2D2) proteins exhibit differential localization and AKAP interaction

A-kinase anchoring proteins (AKAPs) bind to protein kinase A (PKA) via an amphipathic helix domain that interacts with a dimerization/docking domain on the regulatory (R) subunit of PKA. Four other mammalian proteins (ROPN1, ASP, SP17, and CABYR) also contain a highly conserved RII dimerization/docking (R2D2) domain, suggesting all four proteins may interact with all AKAPs in a manner similar to RII. All four of these proteins were originally detected in the flagellum of mammalian sperm. In this report, we demonstrate that all four R2D2 proteins are expressed in a wide variety of tissues and three of the proteins SP17, CABYR, and ASP are located in motile cilia of human bronchus and fallopian tubes. In addition, we detect SP17 in primary cilia. We also provide evidence that ROPN1 and ASP bind to a variety of AKAPs and this interaction can be disrupted with anchoring inhibitor peptides. The interaction of SP17 and CABYR with AKAPs appears to be much more limited. None of the R2D2 proteins appears to bind cAMP, a fundamental characteristic of the regulatory subunits of PKA. These observations suggest that R2D2 proteins utilize docking interactions with AKAPs to accomplish their function of regulating cilia and flagella. Based on location, affinity for AKAPs and lack of affinity for cAMP, it appears that each R2D2 protein has a unique role in this process.     

金雀异黄素对不同淋巴转移能力的小鼠肝癌细胞株的抑制作用

MTT法检测大豆提取物金雀异黄素（genistein,Gen）对不同淋巴转移能力的腹水型小鼠肝癌细胞株HepA-H和HepA-L的生长抑制作用。应用电镜观察细胞形态和流式细胞术检测细胞凋亡。将HepA-H和HepA-L接种NIH小鼠,制备荷瘤动物模型,Gen腹腔给药后第14天取淋巴结观察,并计算转移率。TUNEL法检测淋巴结凋亡细胞,并计算凋亡指数。实验发现：（1）Gen对两株细胞均具有良好的生长抑制作用,且对HepA-H的抑制优于HepA-L;（2）Gen在体外诱导两株细胞发生凋亡,且HepA-H的凋亡率高于HepA-L,并呈量效关系;（3）Gen抑制荷瘤动物肿瘤生长和肿瘤淋巴转移,且对HepA-H的抑制强于HepA-L,实验组H的凋亡指数（3．87％）也显著高于实验组L（1．69％）。故研究认为Gen显著抑制HepA-H和HepA-L肝癌细胞淋巴转移的作用机制,可能与诱导细胞凋亡有关,对高淋巴转移细胞的抑制作用强于低淋巴转移细胞,提示Gen抗肿瘤作用具有一定的选择性。     

A rare protein fluorescence behavior where the emission is dominated by tyrosine: case of the 33-kDa protein from spinach photosystem II

An abnormal fluorescence emission of protein was observed in the 33-kDa protein which is one component of the three extrinsic proteins in spinach photosystem II particle (PS II). This protein contains one tryptophan and eight tyrosine residues, belonging to a "B type protein". It was found that the 33-kDa protein fluorescence is very different from most B type proteins containing both tryptophan and tyrosine residues. For most B type proteins studied so far, the fluorescence emission is dominated by the tryptophan emission, with the tyrosine emission hardly being detected when excited at 280 nm. However, for the present 33-kDa protein, both tyrosine and tryptophan fluorescence emissions were observed, the fluorescence emission being dominated by the tyrosine residue emission upon a 280 nm excitation. The maximum emission wavelength of the 33-kDa protein tryptophan fluorescence was at 317 nm, indicating that the single tryptophan residue is buried in a very strong hydrophobic region. Such a strong hydrophobic environment is rarely observed in proteins when using tryptophan fluorescence experiments. All parameters of the protein tryptophan fluorescence such as quantum yield, fluorescence decay, and absorption spectrum including the fourth derivative spectrum were explored both in the native and pressure-denatured forms.     

Identification of a diverse synthetic abietane diterpenoid library and insight into the structure-activity relationships for antibacterial activity

A diverse natural product-like (NPL) synthetic abietane diterpenoid library containing 86 compounds were obtained and the SARs were studied based on their antibacterial potential. Further in vitro cytotoxic and in silico drug-like properties evaluation showed that the potent antibacterial compound 84 had good drug-like properties and displayed low cytotoxicity toward noncancerous mammalian cells, indicating the study of AA and DHAA might be a good starting point for the search of novel antimicrobial molecules. Future work should be focused on the optimization of their potency and selectivity.     

Characterization of the 3a protein of SARS-associated coronavirus in infected vero E6 cells and SARS patients

Proteomics was used to identify a protein encoded by ORF 3a in a SARS-associated coronavirus (SARS-CoV). Immuno-blotting revealed that interchain disulfide bonds might be formed between this protein and the spike protein. ELISA indicated that sera from SARS patients have significant positive reactions with synthesized peptides derived from the 3a protein. These results are concordant with that of a spike protein-derived peptide. A tendency exists for co-mutation between the 3a protein and the spike protein of SARS-CoV isolates, suggesting that the function of the 3a protein correlates with the spike protein. Taken together, the 3a protein might be tightly correlated to the spike protein in the SARS-CoV functions. The 3a protein may serve as a new clinical marker or drug target for SARS treatment.     

Cysteinyl-tRNA(Cys) formation in Methanocaldococcus jannaschii: the mechanism is still unknown

Most organisms form Cys-tRNA(Cys), an essential component for protein synthesis, through the action of cysteinyl-tRNA synthetase (CysRS). However, the genomes of Methanocaldococcus jannaschii, Methanothermobacter thermautotrophicus, and Methanopyrus kandleri do not contain a recognizable cysS gene encoding CysRS. It was reported that M. jannaschii prolyl-tRNA synthetase (C. Stathopoulos, T. Li, R. Longman, U. C. Vothknecht, H. D. Becker, M. Ibba, and D. S?ll, Science 287:479-482, 2000; R. S. Lipman, K. R. Sowers, and Y. M. Hou, Biochemistry 39:7792-7798, 2000) or the M. jannaschii MJ1477 protein (C. Fabrega, M. A. Farrow, B. Mukhopadhyay, V. de Crécy-Lagard, A. R. Ortiz, and P. Schimmel, Nature 411:110-114, 2001) provides the "missing" CysRS activity for in vivo Cys-tRNA(Cys) formation. These conclusions were supported by complementation of temperature-sensitive Escherichia coli cysS(Ts) strain UQ818 with archaeal proS genes (encoding prolyl-tRNA synthetase) or with the Deinococcus radiodurans DR0705 gene, the ortholog of the MJ1477 gene. Here we show that E. coli UQ818 harbors a mutation (V27E) in CysRS; the largest differences compared to the wild-type enzyme are a fourfold increase in the K(m) for cysteine and a ninefold reduction in the k(cat) for ATP. While transformants of E. coli UQ818 with archaeal and bacterial cysS genes grew at a nonpermissive temperature, growth was also supported by elevated intracellular cysteine levels, e.g., by transformation with an E. coli cysE allele (encoding serine acetyltransferase) or by the addition of cysteine to the culture medium. An E. coli cysS deletion strain permitted a stringent complementation test; growth could be supported only by archaeal or bacterial cysS genes and not by archaeal proS genes or the D. radiodurans DR0705 gene. Construction of a D. radiodurans DR0705 deletion strain showed this gene to be dispensable. However, attempts to delete D. radiodurans cysS failed, suggesting that this is an essential Deinococcus gene. These results imply that it is not established that proS or MJ1477 gene products catalyze Cys-tRNA(Cys) synthesis in M. jannaschii. Thus, the mechanism of Cys-tRNA(Cys) formation in M. jannaschii still remains to be discovered.     

Metabolomic analysis of amino acid and fat metabolism in rats with l-tryptophan supplementation

Tryptophan (TRP) is an important precursor for several neurotransmitters and metabolic regulators, which play a vital role in regulating nutrient metabolism. The purpose of this study was to investigate the effects of tryptophan supplementation on the biochemical profiles, intestinal structure, liver structure and serum metabolome in rats. Rats received daily intragastric administration of either tryptophan at doses of 200 mg/kg body weight per day or saline (control group) for 7 days. TRP supplementation had a tendency to decrease the body weight of rats (P > 0.05). The levels of urea and CHO in serum were decreased in the TRP-supplemented group rats compared with control group rats (P < 0.05). TRP supplementation increased the villus height and the ratio of villus height to crypt depth in the jejunum compared to control group rats (P < 0.05). Metabolic effects of tryptophan supplementation include: (1) increases in the serum concentrations of lysine, glycine, alanine, glutamate, glutamine, citrulline, methionine, tyrosine, 1-methylhistidine, and albumin, and decreases in the concentrations of serum branched-chain amino acid (isoleucine, valine and leucine); (2) decreases in the serum concentrations of formate and nitrogenous products (trimethylamine, TMAO, methylamine and dimethylamine), and in the contraction of trimethylamine in feces; (3) decreases in serum levels of lipids, low density lipoprotein, very low density lipoprotein, together with the elevated ratio of acetoacetate to β-hydroxybutyrate. The results indicate that tryptophan supplementation reduced the catabolism of dietary amino acids and promoted protein synthesis in rats, promoted the oxidation of fatty acid and reduced fat deposition in the body of rats.     

Association of Germline Variation in CCNE1 and CDK2 with Breast Cancer Risk,Progression and Survival among Chinese Han Women

Background

Somatic alterations of cyclin-dependent kinase 2 (CDK2)-cyclin E complex have been shown to contribute to breast cancer (BC) development and progression. This study aimed to explore the effects of single nucleotide polymorphisms (SNPs) in CDK2 and CCNE1 (a gene encoding G1/S specific cyclin E1 protein, formerly called cyclin E) on BC risk, progression and survival in a Chinese Han population.

Methodology/Principal Findings

We herein genotyped 6 haplotype-tagging SNPs (htSNPs) of CCNE1 and 2 htSNPs of CDK2 in 1207 BC cases and 1207 age-matched controls among Chinese Han women, and then reconstructed haplotype blocks according to our genotyping data and linkage disequilibrium status of these htSNPs. For CCNE1, the minor allele homozygotes of three htSNPs were associated with BC risk (rs3218035: adjusted odds ratio [aOR] = 3.35, 95% confidence interval [CI] = 1.69–6.67; rs3218038: aOR = 1.81, 95% CI = 1.22–2.70; rs3218042: aOR = 2.64, 95% CI = 1.31–5.34), and these three loci showed a dose-dependent manner in increasing BC risk (P _trend = 0.0001). Moreover, the 5-SNP haplotype CCGTC, which carried none of minor alleles of the 3 at-risk SNPs, was associated with a favorable event-free survival (hazard ratio [HR] = 0.53, 95% CI = 0.32–0.90). Stratified analysis suggested that the minor-allele homozygote carriers of rs3218038 had a worse event-free survival among patients with aggressive tumours (in tumour size>2 cm group: HR = 2.06, 95% CI = 1.06–3.99; in positive lymph node metastasis group: HR = 2.41, 95% CI = 1.15–5.03; in stage II–IV group: HR = 2.03, 95% CI = 1.09–3.79). For CDK2, no significant association was found.

Conclusions/Significance

This study indicates that genetic variants in CCNE1 may contribute to BC risk and survival in Chinese Han population. They may become molecular markers for individual evaluation of BC susceptibility and prognosis. Nevertheless, further validation studies are needed.