DNA mismatch repair gene mutS (2.56 kb) was PCR modified and cloned into a secretive prokaryotic expression vector pET32a (+) which carries a N-terminal His.tag + and thioredoxin sequence. MutS protein was expressed with high level after IPTG induction using the strain E. coli AD494(DE3). SDS-PAGE revealed that the expected protein with a molecular weight of 108 kD which is about 35% of the total bacterial proteins is almost soluble. The expected protein was purified directly by immobilized metal (Ni2+) chelation affinity chromatography and the purity is over 90%. MutS protein activity verified using mismatch DNA showed that the expression product can recognize and bind to base-pair mismatch specifically.
Adenosine Triphosphatases ; biosynthesis ; genetics ; isolation & purification ; Bacterial Proteins ; Base Pair Mismatch ; Chromatography, Affinity ; DNA ; metabolism ; DNA Repair ; DNA-Binding Proteins ; Escherichia coli Proteins ; biosynthesis ; genetics ; isolation & purification ; Magnesium ; pharmacology ; Molecular Weight ; MutS DNA Mismatch-Binding Protein ; Recombinant Proteins ; biosynthesis

This study was aimed to identify pET21b-HPV16E2/BL21(DE3) strain and to optimize the expression of human papillomavirus type 16 (HPV16) E2 protein by orthogonal analysis. Four influence factors on two levels were selected to increase the target protein quantity. The four factors were induction time, induction temperature, inductor concentration and cell density. The quantity of HPV16 E2 protein was used as the evaluation parameter. Induced by IPTG, HPV16 E2 protein was analyzed by SDS-PAGE and Western Blot. Target protein was analyzed by GIS imaging system to quantify the protein level. SPSS13. 0 software was applied to analyze the result. Data showed that the expression strain pET211rHPV16 E2/BL21(DE3) was identified correctly. HPV16 E2 protein expressed mainly at insoluble form. The 42KD protein band was identified by SDS-PAGE and Western blot. Orthogonal test was applied on influence factor analysis and expression optimization successfully. Main influence factors were inductor concentration and induction temperature. The optimimum condition of maximum expression quantity was 37 degrees C, 7h, 1.0 mmol/L IPTG and OD600 1.0. In this experiment, orthogonal test could not only be used to analyze the influential factors and promote the target protein expression, but also be used to provide a better experiment method for molecular biological study.
DNA-Binding Proteins ; biosynthesis ; genetics ; Genetic Vectors ; genetics ; Human papillomavirus 16 ; metabolism ; Humans ; Oncogene Proteins, Viral ; biosynthesis ; genetics ; Papillomavirus Infections ; virology ; Recombinant Proteins ; biosynthesis ; genetics

HPV-2 is a very common type of HPV which causes common warts. The E2 protein of virus can repress the activity of the viral early promoter through binding to the specific binding sites in viral LCR. Previously we reported that the repression of a mutated E2 protein of HPV-2 isolated from a patient with huge common wart on the viral early promoter was obviously decreased, and A338V mutation located at the C terminal DNA binding region of E2 protein. In this study, we expressed and purified the recombinant mutated and prototype E2 fusion proteins, both in the contexts of the C terminal and the full length, by prokaryotic expression system. The electrophoretic mobility shift assay showed E2 protein could bind to double-stranded DNA oligos labeled with biotin that covered two E2 binding sites. The DNA binding abilities of both C terminal and full-length mutated E2 proteins were stronger than the prototype analogs. This result indicates that the enhancement of the mutated E2 DNA binding ability may be the molecular mechanism for its impact on the activity of viral promoter, which correlates with the phenotype of extensive common wart.
DNA ; metabolism ; DNA-Binding Proteins ; biosynthesis ; genetics ; isolation & purification ; metabolism ; Electrophoresis ; Genetic Vectors ; genetics ; Mutation ; Papillomaviridae ; Promoter Regions, Genetic ; genetics ; Protein Binding ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; metabolism ; Viral Proteins ; biosynthesis ; genetics ; isolation & purification ; metabolism

We expressed recombinant single-stranded DNA-binding protein (r-SSBP) from Escherichia coli with the molecular weight of 24-kDa by using genetic engineering strategy, and demonstrated the single-stranded DNA (ssDNA)-binding activity of r-SSBP by electrophoretic mobility shift assay (EMSA). To further characterize r-SSBP, we studied the effects of r-SSBP on melting temperature (T(m)) of DNA. The results showed that r-SSBP could bind to ssDNA, and lower the T(m) of DNA, especially for single-base mismatched DNA. Therefore, r-SSBP significantly increased the T(m) difference between single-base mismatched DNA and perfect matched DNA. These results are very beneficial for single-nucleotide polymorphism detection. Moreover, we applied r-SSBP in high sensitive pyrosequencing system developed by our group. The results suggest that the r-SSBP decreased non-specific signals, corrected the proportion of signal peak height and improved the performance of pyrosequencing.
DNA-Binding Proteins ; biosynthesis ; genetics ; Diphosphates ; metabolism ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Analysis, DNA ; methods

AIMTo characterize the coexpression of survivin, an inhibitor of apoptosis (IAF), and human telomerase reverse transcriptase (hTERT) in human testes with varying spermatogenic function.

METHODSTranscript levels of survivin mRNA and hTERT mRNA were determined in normal testes (n=11) and testes with defective spermatogenesis (n=28) using real-time reverse-transcription polymerase chain reaction (RT-PCR). The histological work-up was performed according to a modified Johnsen score.

RESULTSExpressions of both survivin and hTERT were highest at median levels of 96.8 and 709 in normal spermatogenesis and dropped to 53.3 and 534 in testes with postmeiotic spermatogenic arrest (n=10). In severe spermatogenic failure (n=18), survivin expression was lacking in most specimens (n=16), whereas at least low levels of testicular hTERT expression were largely detectable with a normalized expression of 73 in premeiotic spermatogenic arrest (n=7) and 45 in patients with Sertoli cell-only syndrome (SCOS) (n=3). Both survivin and hTERT expressions increased with a progressing Johnsen score (P for trend=0.001).

CONCLUSIONAlthough both survivin and hTERT are correlated with spermatogenic function, they show different expression patterns in testes of infertile patients. These findings substantiate results from studies in the rodent testis suggesting a predominant expression of survivin in meiotically dividing germ cells.

Biopsy ; DNA-Binding Proteins ; biosynthesis ; Gene Expression ; physiology ; Humans ; Infertility, Male ; metabolism ; Inhibitor of Apoptosis Proteins ; Male ; Microtubule-Associated Proteins ; biosynthesis ; Neoplasm Proteins ; biosynthesis ; Spermatogenesis ; physiology ; Telomerase ; biosynthesis ; Testis ; metabolism

OBJECTIVETo explore the correlation of chemotherapy efficacy in tongue squamous cell carcinoma(SCC) with expression level of P-glycoprotein(Pgp), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), glutathiones-tranferase (GST-pi), DNA topo-isomerase II alpha (Topo II alpha).

METHODSThe expression patterns of Pgp, MRP, LRP, GST-pi and Topo II alpha in 40 patients (pre and post-chemotherapy, respectively) with tongue SCC were examined by immunohistochemically labelled streptavidin bioein method (LsAB).

RESULTSThe expression ratios of Pgp, MRP, LRP, GST-pi and Topo II alpha in pre-chemotherapy cases were 47.5%, 50%, 35%, 45%, 82.5%, respectively. No relations between expression of Pgp, MRP, LRP, GST-pi, Topo II alpha and clinic indexes were established (P > 0.05). Expression ratios of Pgp, MRP in post-chemotherapy cases were higher than that in pre-chemotherapy cases (P < 0.05). Expression of Pgp and MRP showed relevance with drug resistance (P < 0.05). The co-expression was common, the ratios of co-expression of Pgp, MRP, GST-pi and MRP, GST-pi in chemotherapy non-responders were 40% and 50%, respectively, but 0 in responders.

CONCLUSIONThe intrinsic multidrug resistance of tongue SCC is relevant to the effects of Pgp, MRP, GST-pi.

ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; genetics ; Adult ; Antigens, Neoplasm ; Carcinoma, Squamous Cell ; metabolism ; DNA Topoisomerases, Type II ; biosynthesis ; genetics ; DNA-Binding Proteins ; Female ; Glutathione S-Transferase pi ; Glutathione Transferase ; biosynthesis ; genetics ; Humans ; Isoenzymes ; biosynthesis ; genetics ; Male ; Middle Aged ; Multidrug Resistance-Associated Proteins ; biosynthesis ; genetics ; Neoplasm Proteins ; biosynthesis ; genetics ; Random Allocation ; Tongue Neoplasms ; metabolism ; Vault Ribonucleoprotein Particles ; biosynthesis ; genetics

OBJECTIVETo investigate the interferon alpha regulation mechanisms by screening binding proteins of interferon alpha promoter by phage display.

METHODSPCR product of interferon-alpha promoter was incubated with a phage display cDNA library that expressed a library of human liver proteins on the surface of bacteriophage T7. Unbound phages were washed off and the phages bound to the interferon alpha promoter were amplified. Positive plaques were amplified by PCR and cloned into a pGEM-Teasy vector in order to perform DNA sequence analysis and subsequent computer blasting analysis.

RESULTSPositive phage-displayed proteins binding with interferon alpha promoter were enriched after five rounds of biopanning. We found that the following proteins were relevant to interferon alpha: mitochondrial ribosomal protein, chromosome clone, fibrinogen A alpha polypeptide, enoyl coenzyme A hydratase short chain, eukaryotic translation elongation factor 1 alpha, PI-3-kinase-related kinase SMG-1-like, xeroderma pigmentosum C group, and Homo sapien activity-dependent neuroprotector (ADNP).

CONCLUSIONMany proteins with different functions could bind with interferon alpha promoter.

DNA, Complementary ; genetics ; DNA-Binding Proteins ; biosynthesis ; genetics ; Gene Library ; Hepatocytes ; cytology ; metabolism ; Humans ; Interferon-alpha ; biosynthesis ; genetics ; Promoter Regions, Genetic ; genetics ; Two-Hybrid System Techniques

Antimicrobial Cationic Peptides ; biosynthesis ; genetics ; DNA-Binding Proteins ; biosynthesis ; genetics ; Humans ; Microbial Sensitivity Tests ; Muramidase ; biosynthesis ; genetics ; Peptides, Cyclic ; biosynthesis ; genetics ; Pichia ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification

OBJECTIVETo study the effect of As2O3 induction of HeLa cell apoptosis on HPV18 E6 expression and telomerase activity.

METHODSHeLa cells were treated with As2O3 in various concentrations. The effect of As2O3 on HeLa cell survival and apoptosis was determined by MTT assay, light and electron microscopy, and flow cytometry. Telomerase activity in HeLa cells was determined by TRAP-ELISA and the expression of HPV18 E6 mRNA was assayed by RT-PCR.

RESULTSAfter being treated with 2 micromol/L As2O3 for 48 h, the survival of HeLa cells decreased, and marked apoptosis was observed in a time- and dose-dependent manner. There was a good correlation between cell apoptosis and viral E6 gene expression and inhibition of telomerase activity following As2O3 treatment.

CONCLUSIONThe molecular mechanisms of As2O3 effect on HeLa cells may be related to down-regulation of HPV18 E6 oncogene expression and inhibition of telomerase activity.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Arsenicals ; pharmacology ; DNA-Binding Proteins ; biosynthesis ; genetics ; Down-Regulation ; HeLa Cells ; Humans ; Oncogene Proteins, Viral ; biosynthesis ; genetics ; Oxides ; pharmacology ; Telomerase ; metabolism

MRE11 plays an important role in the signal transduction of DNA damage response, therefore this study was purposed to explore the relationship between hMRE11 focus formation and DNA double-strand breaks (DSBs) caused by etoposide (VP-16) in human promonocytic cells U937. After U937 cells were treated with VP-16, the drug-induced DSBs were assessed by pulsed-field gel electrophoresis (PFGE), the gene transcription levels of hMRE11 were evaluated by RT-PCR, the nuclear focus formation of hMRE11 protein was examined using immunofluorescence technique, the cell cycle in parallel was analyzed by flow cytometry. The results showed that the percentage of U937 cells with DSBs induced by VP-16 raised from 13.0 +/- 2.3% in VP-16 2 microg/ml to 32.0 +/- 4.3% in VP-16 20 microg/ml (P < 0.01) along with increase of VP-16 dose. No difference of the hMRE11 mRNA level in U937 cells following the treatment with 100 microg/ml VP-16 at different times was discovered (P > 0.05). The hMRE11 protein was abundantly and uniformly distributed in the nuclei of untreated U937 cells outside of nucleoli, however, it formed discrete nuclear foci following VP-16 treatment. The mean value of nuclear foci increased by 5 to 20 times following the drug dosing (P < 0.01). An average of 5 nuclear foci per positive nucleus were observed at a dose of 2 microg/ml, and it was increased to an average of over 14 nuclear foci per positive nucleus after treating with VP-16 20 microg/ml. The percentage of nuclei containing hMRE11 nuclear foci also increased from less than 10% after treatment wiht VP-16 2 microg/ml to over 50% after VP-16 20 microg/ml (P < 0.01) following treatment with VP-16. After U937 cells were treated with 100 microg/ml VP-16 for 2 hours and fixed at 4, 8, 12 and 24 hours, the percentage of nuclei with hMRE11 nuclear foci increased to 61.54 +/- 3.6% (the control U937 cells: 0.47 +/- 1.17%, P < 0.01) at 8 hours, with a subsequent decrease in the percentage of nuclear foci-positive cells by 24 hours. The ratio of S-phase U937 cells at 8 hours after being treated with 100 microg/ml VP-16 for 2 hours was 47.55 +/- 2.35%, and that without 100 microg/ml VP-16 was 21.95 +/- 2.91% (P < 0.05). It is concluded that the nuclear focus formation of hMRE11 protein may be a response to DNA damage induced by topoisomerase II inhibitor VP-16 in human promonocytic cell line U937.
Antineoplastic Agents, Phytogenic ; pharmacology ; DNA Damage ; DNA Repair ; genetics ; physiology ; DNA-Binding Proteins ; biosynthesis ; genetics ; metabolism ; physiology ; Dose-Response Relationship, Drug ; Etoposide ; pharmacology ; Humans ; MRE11 Homologue Protein ; Protein Binding ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; Topoisomerase II Inhibitors ; U937 Cells