Leader peptidase is a novel serine protease in Escherichia coli, which catalyzes the cleavage of amino-terminal signal sequences from exported proteins. It is an integral membrane protein containing two transmembrane segments with its carboxy-terminal catalytic domain residing in the periplasmic space. Recently, the x-ray crystal structure of signal peptidase-inhibitor complex showed that Asp 280, a highly conserved consensus sequence of E. coli leader peptidase is the closest charged residue in the vicinity of two catalytic dyad, Ser 90 and Lys 145, and it is likely held in place by a salt bridge to Arg 282. Possible roles of Asp 280 and Arg 282 in the structure-catalytic function relationship were investigated by the site-directed mutagenesis of Asp 280 substituted with alanine, glutamic acid, glycine, or asparagine and of Arg 282 with methionine. All of mutants purified with nickel affinity chromatography were inactive using in vitro assay. It is surprising to find complete lose of activity by an extension of one carbon units in the mutant where Asp 280 is substituted with glutamic acid. These results suggest that Asp 280 and Arg 282 are in a sequence which constitutes catalytic crevice of leader peptidase and are essential for maintaining the conformation of catalytic pocket.
Aspartic Acid/chemistry* ; Bacterial Outer Membrane Proteins/metabolism ; Blotting, Western ; Escherichia coli/enzymology* ; Escherichia coli/chemistry ; Micrococcal Nuclease/metabolism ; Mutagenesis, Site-Directed ; Oligonucleotides ; Protein Precursors/metabolism ; Serine Endopeptidases/metabolism* ; Serine Endopeptidases/genetics ; Serine Endopeptidases/chemistry* ; Structure-Activity Relationship

Thrombin-like enzymes (TLEs) are studied widely because of their therapeutic potential in myocardial infarction and thrombotic diseases. We synthesized the DNA fragment encoding thrombin-like enzyme calobin from Agkistrodon caliginosus (Korean Viper) venom by fusion PCR and expressed it in Pichia pastoris. After induction by 0.5% methanol for 48 h, the expression level of recombinant calobin reached 3.5 g/L in medium. The recombinant calobin was purified by Q-Sepharose Fast Flow ion-exchange chromatography and Sephacryl-S-100 gel filtration chromatography. Purified sample had a molecular weight of 32 kD shown in SDS-PAGE. It hydrolyzed fibrinogen and formed a light white hydrolysis circle in fibrinogen plate. SDS-PAGE analysis showed that recombinant calobin cleaved Aalpha-chain of fibrinogen specifically, and produced an appropriately 40 kD new band. However, we failed to find its fibrin-clot formation activity.
Agkistrodon ; Animals ; Pichia ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; Serine Endopeptidases ; biosynthesis ; genetics ; Thrombin ; biosynthesis ; genetics ; Viper Venoms ; enzymology

OBJECTIVETo investigate the heterozygous genotype and molecular characteristics of Organophosphorus resistance associated with heterozygous Estbeta2 of esterase B2 gene from natural population of Culex pipiens complex.

METHODSGenomic DNA was extracted from natural populations of Culex pipiens complex in Hangzhou. The PCR-restriction fragment length polymorphism (PCR-RFLP) assay was applied to type the resistance associated esterase gene. Estbeta2 of esterase B2 gene was identified by PCR-RFLP, and the genotyping for heterozygous Estbeta2 was carried out after restriction enzyme digesting by Bfm I endonuclease.

RESULTSThe DNA was isolated from 207 Culex pipiens respectively, while 156 PCR samples showed positive and the positive rate was 75.36% (156/207). The PCR-RFLP assay of esterase B2 gene revealed that the Estbeta2 was accounted about 28.20% (44/156) in 156 positive samples. There were two genotypes identified, namely homozygous Estbeta2 (90.90%, 30/33) and heterozygous Estbeta2 (9%, 3/33), heterozygous Estbeta2 was in existence of a hybrid form as which combined with Estbeta2 and a subtype (Estbeta2/Estbeta2(1)).

CONCLUSIONHeterozygous Estbeta2 of Organophosphorus resistance associated with esterase genotype was determined in natural population of Culex pipiens, and a genotyping method was established.

Animals ; Culex ; enzymology ; genetics ; Genes, Insect ; Genotype ; Heterozygote ; Insecticide Resistance ; genetics ; Insecticides ; pharmacology ; Organophosphorus Compounds ; pharmacology ; Phenotype ; Serine Endopeptidases ; genetics

In a 5L fermentor the production conditions of alkaline protease gene engineering strain BA071 were investigated. The maximum activity of alkaline protease reached 24,480 u/mL in 40 hours of fermentation by combination of enhancing aeration and changing the agitation rate. The fast purification method of recombinant protease was conducted with FPLC (Fast Protein Liquid Chromatography). The crude enzyme, treated with ammonium sulfate fractionation and decolored with DEAE-A-50 and polyethylene glycol concentration, was purified with CM-Sephadex-C-50 and Sephadex-G-75. The purified enzyme appears homologous on SDS-PAGE. The purity of enzyme was increased 76.2 times. SDS-PAGE analysis showed that the molecular weights of expressed recombinant products were about 28 kD. The optimal reaction pH and temperature of recombinant enzyme were at pH11 and 60 degrees C, respectively. The recombinant enzyme exhibited high temperature tolerance and was stable at a wide range of pH. Ca2+, MG2+ can enhance the stability of the recombinant enzyme. While the protease activity of the enzyme was strongly inhibited by Hg2+, Ag+, PMFS [symbol: see text] DFP, and was not affected by SDS and Urea.
Bacillus ; genetics ; metabolism ; Enzyme Stability ; Fermentation ; Genetic Engineering ; Metals ; pharmacology ; Recombinant Proteins ; biosynthesis ; Serine Endopeptidases ; genetics ; isolation & purification ; metabolism

This study was aimed to construct a prokaryotic expressing vector of Hap gene from Nontypeable Haemophilus influenzae, and express and identify the fusion proteins of Hap-His in E. coli. The gene encoding protein Hap was amplified from Nontypeable Haemophilus influenzae ATCC49247 chromosomal DNA by PCR, then it was cloned into prokaryotic expression plasmid pET-32a (+). The recombinant plasmid pET-32a(+)-Hap was transformed into E. coli BL21 and expression was induced by Isopropy-beta-D-thiogalatoside(IPTG). The Hap-His fusion protein expressed so was analyzed by SDS-PAGE and Western-blot. The results showed that the recombinant expressive plasmid pET-32a (+)-Hap was constructed successfully, and the recombinant plasmid expressed Hap-His fusion protein with relative molecule mass 176 000 and mainly existed in inclusion body. This fusion protein could combine with anti-His monoclonal antibody specifically through Western blot analysis. Successful expression of Hap-His fusion protein in prokaryotic cell could lay a basis for further study of immunocompetence of Hap protein and development of NTHi vaccine.
Bacterial Outer Membrane Proteins ; biosynthesis ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Haemophilus influenzae ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Serine Endopeptidases ; biosynthesis ; genetics

BACKGROUNDPreeclampsia, characterized by hypertension and proteinuria, is a multifactorial disease associated with shallow invasion of trophoblast cells and inadequate spiral artery remodeling. Trophoblast and tumor cells have similar invasion mechanism. Prostasin is closely related to tumor development, invasion and metastasis and influences blood pressure through activating epithelial sodium channel. The effect of prostasin on the pathogenesis of preeclampsia remains unclear. This study investigated the association of prostasin gene at rs12597511 with severe preeclampsia.

METHODSA single nucleotide polymorphism, rs12597511, was tested with polymerase chain reaction and restrictionfragment length polymorphism analyses in 179 severe preeclampsia patients and 222 normal pregnant women.

RESULTSThe frequencies of TC + CC genotypes were significantly higher in severe preeclampsia group compared with in control group (the adjusted odds ratio was 2.030, 95% confidence interval 1.195-3.449, P = 0.009). The C allele of rs12597511 was present significantly more often among women with severe preeclampsia (P = 0.001). Genotyping analysis showed that the C allele of rs12597511 could confer a risk for severe preeclampsia.

CONCLUSIONThe higher frequency of C allele of prostasin gene at rs12597511 is associated with severe preeclampsia.

Adult ; Female ; Gene Frequency ; genetics ; Genetic Predisposition to Disease ; genetics ; Genotype ; Humans ; Middle Aged ; Polymorphism, Single Nucleotide ; genetics ; Pre-Eclampsia ; genetics ; Pregnancy ; Serine Endopeptidases ; genetics ; Young Adult

Fusion between the transmembrane protease serine 2 and v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG fusion) is a common genetic alteration in prostate cancer among Western populations and has been suggested as playing a role in tumorigenesis and progression of prostate cancer. However, the prevalence of TMPRSS2-ERG fusion differs among different ethnic groups, and contradictory results have been reported in Asian patients. We aim to evaluate the prevalence and significance of TMPRSS2-ERG fusion as a molecular subtyping and prognosis indicator of prostate cancer in Asians. We identified the fusion status in 669 samples from prostate biopsy and radical prostatectomy by fluorescence in situ hybridization and/or immunohistochemistry in China. We examined the association of TMPRSS2-ERG fusion with clinicopathological characteristics and biochemical recurrence by Chi-square test and Kaplan-Meier analysis. Finally, a systematic review was performed to investigate the positive rate of the fusion in Asian prostate cancer patients. McNemar's test was employed to compare the positive rates of TMPRSS2-ERG fusion detected using different methods. The positive rates of TMPRSS2-ERG fusion were 16% in our samples and 27% in Asian patients. In our samples, 9.4% and 19.3% of cases were recognized as fusion positive by fluorescence in situ hybridization and immunohistochemistry, respectively. No significant association between the fusion and clinical parameters was observed. TMPRSS2-ERG fusion is not a frequent genomic alteration among Asian prostate cancer patients and has limited significance in clinical practices in China. Besides ethnic difference, detection methods potentially influence the results showing a positive rate of TMPRSS2-ERG fusion.
Aged ; China ; Humans ; Male ; Middle Aged ; Oncogene Fusion/genetics* ; Oncogene Proteins, Fusion/genetics* ; Prostatic Neoplasms/genetics* ; Serine Endopeptidases/genetics* ; Transcriptional Regulator ERG/genetics*

Extracellular serine protease SFP2 from Streptomyces fradiae var. k11 with high feather-degrading activity was purified. The partial amino acid sequences of internal peptide of purified SFP2 were determined, and the partial gene encoding SFP2 was cloned by PCR using the degenerate primers designed according to the amino acid sequences. Complete sfp2 gene was cloned by screening the genomic DNA library of Streptomyces fradiae var. k11. The Open Reading Frame of sfp2 including pre- pro-enzyme is 924bp long (EMBL Accession number: AJ784940). The signal peptide sequence is as long as 114bp, the precursor sequence is 810bp and the mature enzyme is 576bp long, encoding 191 amino acid resides with the putative molecular weight of 19.112kD. In E. coli and Bacillus subtilis, the two sequences encoding SFP2 pro-enzyme and mature enzyme were both expressed successfully. The pro-enzyme expressed had normal biological function and its mature product had normal enzymatic activity.
Amino Acid Sequence ; Bacillus subtilis ; genetics ; metabolism ; Base Sequence ; Escherichia coli ; genetics ; metabolism ; Molecular Sequence Data ; Serine Endopeptidases ; genetics ; metabolism ; Streptomyces ; enzymology ; genetics

OBJECTIVETo establish a cell model of secreted alkaline phosphatase (SEAP) co-controlled by HCV 5'NCR and NS3 serine protease in an effort to develop new antiviral agents.

METHODSThe fragments of HCV 5'NCR and NS3/4A-SEAP were amplified by PCR. They were fused into pBluescript SK+ to generate 5'NCR-NS3/4A-SEAP chimeric plasmid. The resulting chimeric gene was subcloned into HindIII/Bsu36 I site of pSEAP2-Control (a SEAP eukaryotic expression plasmid), to generate pNCR-NS3/4A-SEAP, in which the SEAP was fused in-frame to the downstream of NS4A/4B cleavage site. The SEAP activity in the culture media of transiently transfected cells was monitored quantitatively. The regulatory effect of HCV 5'NCR and NS3 serine protease on SEAP expression was measured by treatment of transfected cells with antisense oligodeoxynucleotide (ASODN) against HCV 5'NCR and TPCK, a irreversible serine protease inhibitor.

RESULTSThe SEAP activity in the culture media reached 80801+/-4794 RLU, and was significantly inhibited by 5 micromol/L, 10 micromol/L of ASODN (t=4.315, p<0.01; t=6.985, p<0.001) and 100 micromol/L of TPCK (t=6.949, P<0.001).

CONCLUSIONA cell model of SEAP co-controlled by HCV 5'NCR and NS3 serine protease has been successfully established. This might promote the screening of anti-viral drugs

Alkaline Phosphatase ; secretion ; Antiviral Agents ; Drug Evaluation, Preclinical ; Hepacivirus ; genetics ; Hepatocytes ; enzymology ; virology ; Humans ; Recombinant Proteins ; biosynthesis ; genetics ; Serine Endopeptidases ; biosynthesis ; genetics ; Viral Nonstructural Proteins ; biosynthesis ; genetics

Animals ; Cell Differentiation ; Hepatocyte Growth Factor ; genetics ; metabolism ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mouse Embryonic Stem Cells ; cytology ; metabolism ; Protein Precursors ; genetics ; metabolism ; Serine Endopeptidases ; genetics ; metabolism