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

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

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

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

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

Objective of this study was to detect the expression of HtrA2 and WT1 mRNA in acute myeloid leukemia (AML) and investigate the relationship of their expression levels with clinical variates and correlation between them. The expression levels of HtrA2 and WT1 were measured by RQ-PCR in bone marrow cells in 104 newly diagnosed AML patients and leukemia cell lines (K562, HL-60, NB4, Kasumi-1, U937), and the relationship between expression level and clinical parameters (age, sex, WBC count, diagnosis and prognosis) was investigated. The results showed that (1) the expression of HtrA2 gene in newly diagnosed AML was lower than that of the normal controls (P < 0.01), while expression of WT1 gene in newly diagnosed AML was higher than that of the normal controls (P < 0.01), the expression levels of HtrA2 and WT1 genes both did not correlate with age, sex and WBC counts of patients. There were no significant difference of HtrA2 gene expression between different NCCN prognosis group, while WT1 gene expression in better-risk group was significantly lower than that in intermediate-risk group (P = 0.003). The HtrA2 expression level rose after treatment in both CR group and non-CR group (P < 0.05), while WT1 expression level significantly decreased after treatment only in CR group (P < 0.01). Negative correlation between HtrA2 and WT1 expression was also observed (r = -0.249, P = 0.011). It is concluded that the low expression of HtrA2 and high expression of WT1 are closely related with occurrence and development of acute leukemia, so up-regulating expression of HtrA2 and interfering expression of WT1 may become the targets for leukemia therapy in the future.
Adolescent ; Adult ; Aged ; Cell Line, Tumor ; Female ; High-Temperature Requirement A Serine Peptidase 2 ; Humans ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Male ; Middle Aged ; Mitochondrial Proteins ; genetics ; metabolism ; Serine Endopeptidases ; genetics ; metabolism ; WT1 Proteins ; genetics ; metabolism ; Young Adult

This study was aimed to investigate the expression of RHBDD1 gene in patients with chronic myeloid leukemia (CML) and explore its clinical significance. The relative expression levels of RHBDD1 in bone marrow mononuclear cells of healthy controls and CML patients were detected by using real time PCR. The results showed that the expression level of RHBDD1 in CML patients was significantly higher than that in healthy controls. The expression level of RHBDD1 in CML patients with negative BCR/ABL p210 was remarkably higher than that in patients with positive BCR/ABL p210. In patients ≥ 50 years old RHBDD1 expression was lower than the patients < 50 years old. There were no significant relation of RHBDD1 expression with sex of patients. It is concluded that RHBDD1 gene may be involved in the pathogenesis and progression of CML, particularly reflects in the pathogenesis of the patients with negative BCR/ABL p210.
Bone Marrow Cells ; metabolism ; pathology ; Case-Control Studies ; Female ; Gene Expression ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; metabolism ; pathology ; Male ; Middle Aged ; Serine Endopeptidases ; genetics ; metabolism

OBJECTIVETo explore the expression of serine protease Omi/HtrA2 in gastric carcinoma tissue and its association with clinicopathological features and prognosis.

METHODSOmi/HtrA2 protein expression levels were detected by immunohistochemistry method in resected gastric carcinomas(n=68), adjacent noncancerous tissues(n=15), and normal tissues(n=15), and its association with clinicopathological features and prognosis were analyzed.

RESULTSOmi/HtrA2 expression was positive in 73.5%(50/68) of gastric cancer tissues, which was significantly higher than that in adjacent noncancerous tissues and normal tissues(P<0.05). There were no significant differences in Omi/HtrA2 expression with respect to sex, age, tumor size, and depth of invasion(all P>0.05). Omi/HtrA2 expression level was significantly associated with tumor differentiation, extent of lymph node metastasis, and tumor stage(all P<0.05). Overall 5-year survival rate of patients with gastric carcinoma was 63.3%. Five-year survival rate was higher in Omi/HtrA2 positive cases than Omi/HtrA2 negative cases(72.0% vs. 61.1%), however the difference was not statistically significant.

CONCLUSIONSOmi/HtrA2 expression is more common in gastric carcinoma. Omi/HtrA2 expression is associated with tumor differentiation, extent of lymph node metastasis, and tumor stage.

Adult ; Aged ; Aged, 80 and over ; Female ; High-Temperature Requirement A Serine Peptidase 2 ; Humans ; Male ; Middle Aged ; Mitochondrial Proteins ; genetics ; metabolism ; Neoplasm Staging ; Prognosis ; Serine Endopeptidases ; genetics ; metabolism ; Stomach ; metabolism ; pathology ; Stomach Neoplasms ; metabolism ; pathology ; Young Adult

Carcinoma ; genetics ; metabolism ; pathology ; surgery ; China ; Humans ; Male ; Oncogene Proteins, Fusion ; genetics ; Prostatic Hyperplasia ; genetics ; metabolism ; pathology ; surgery ; Prostatic Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Proto-Oncogene Proteins c-ets ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Serine Endopeptidases ; genetics ; metabolism