Roquyya Gul

Heterologous Secretory Expression and Characterization of Dimerized Bone Morphogenetic Protein 2 in Bacillus subtilis

Recombinant human Bone Morphogenetic Protein 2 (rhBMP2) has important applications in the spine fusion and ortho/maxillofacial surgeries. Here we first report the secretory expression of biological active dimerized rhBMP2 from Bacillus subtilis system. The mature domain of BMP2 gene was amplified from pTz57R/BMP2 plasmid. By using pHT43 expression vector two constructs, pHT43-BMP2-M (single BMP2 gene) and pHT43-BMP2-D (two BMP2 genes coupled with a linker to produce a dimer), were designed. After primary cloning (DH5α strain) and sequence analysis, constructs were transformed into Bacillus subtilis for secretory expression. Expression conditions like media (2xYT) and temperature (30°C) were optimized. Maximum 35% and 25% secretory expression of monomer (~13 kDa) and dimer (~25 kDa), respectively, were observed on SDS-PAGE in SCK6 strain. The expression and dimeric nature of rhBMP2 were confirmed by western blot and native PAGE analysis. For rhBMP2 purification, 200 ml culture supernatant was freeze dried to 10 ml and dialyzed (Tris-Cl, pH 8.5) and Fast Protein Liquid Chromatography (6 ml, Resource Q column) was performed. The rhBMP2 monomer and dimer were eluted at 0.9 M and 0.6 M NaCl, respectively. The alkaline phosphatase assay of rhBMP2 (0, 50, 100, 200, and 400 ng/ml) was analyzed on C2C12 cells and maximum 200 ng/ml activity was observed in dose dependent manner.

Expression and sequence characterization of growth hormone binding protein of Nili-Ravi buffaloes ( Bubalus bubalis )

The growth hormone binding protein (GHBP) was isolated from the liver of Nili-Ravi buffaloes ( Bubalus bubalis ), reverse transcriptase-polymerase chain reaction (RT-PCR) amplified and sequence characterized. RT-PCR analysis demonstrated high degree sequence identities (97.3 to 99.6%) of Bb GHBP cDNA with Bos taurus , Ovis aries and Capra hircus . An expression plasmid was constructed for the production of Bb GHBP in Escherichia coli BL21 (RIPL) CodonPlus under the control of T7lac promoter. On induction with isopropyl β-D thiogalactopyranoside, the Bb GHBP was expressed at levels >30% of the total E. coli proteins. The target protein expressed as inclusion bodies was solubilized in denaturing solution and refolded by step/pulsatile dilution method using cysteine and cystine redox potential. Purification to near homogeniety (>98%) was achieved by ion-exchange chromatography with a recovery yield of 64%. Mass spectrometric analysis of the purified Bb GHBP showed a single peak of 30,756 Da. A radioprotein assay evaluated the binding affinity of recombinant Bb GHBP with iodinated bovine growth hormone (bGH) which demonstrated active conformation of Bb GHBP. These results demonstrate high expression and sequence characterization of Bb GHBP in Nili-Ravi buffaloes and provide the basis for the assessment of Bb GHBP in other breeds of buffalo. Keywords: Liver, Nili-Ravi buffalo, GHBP, MALDI-TOF mass spectrometry, radioprotein binding assay, refolding

Mutation in DsbA signal sequence hampers the SRP mechanism: A new strategy to combat virulence factor

Disulphide bond (Dsb) protein, characterized as an important virulence factor in gram negative bacteria. In this study, amino acid mutations in DsbA signal sequence (ss) and its effect on translocation of recombinant Ovine growth hormone (rOGH) was observed. Eight constructs were designed on the basis of increased hydrophobicity and showed that hydrophobicity and specificity of amino acid plays a crucial role in translocation of rOGH. Two DsbAss with the same hydropathy (1.539), one had alteration at -13 and second at -11 position; alanine (Ala) to isoleucine respectively were designed. The former DsbAss translocated rOGH from membrane to cytoplasmic fraction in E. coli as confirmed by SDS-PAGE, Western blot and molecular modelling analysis. MD simulations and binding free energy calculations evidenced that, altering Ala changed the orientation of signal peptide in the Ffh-M domain binding groove and hampered the process of translocation while change at position -11 pointed it outward. We hypothesize, amino acid and position of mutations in DsbAss can hinder the translocation process of signal recognition particle system, thus affecting the virulence of bacteria.

Microwave-assisted synthesis and evaluation of type 1 collagen–apatite composites for dental tissue regeneration:

The aim was to develop an economical and biocompatible collagen-based bioactive composite for tooth regeneration. Acid-soluble collagen was extracted and purified from fish scales. The design was innovated to molecularly tailor the surface charge sites of the nano-apatite providing chemical bonds with the collagen matrix via microwave irradiation technique. The obtained collagen was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. The composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry, and scanning electron microscopy. MC3T3-E1 cell lines were used to assess the biological effects of these materials by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetra zolium bromide (MTT) assay. Indirect contact test was performed by extracting representative elutes in cell culture media and sulforhodamine B analysis was performed. Chorioallantoic membrane assay was conducted to define the new vessels formation behavior. The purity of collagen extracts was determined and showed two α-chains, i.e. the characteristic of type I collagen. Fourier transform infrared spectroscopy showed the characteristic peaks for amide I, I, III, and phosphate for collagen and composites. Scanning electron microscopy images showed three-dimensional mesh of collagen/apatite nano-fibers. Nontoxic behavior of composites was observed and there were graded and dose-related effects on experimental compounds. The angiogenesis and vessels formation behavior were observed in bioactive collagen composite. The obtained composites have potential to be used for tooth structure regeneration.

Comparative Analysis Of Serum Proangiogenic Biomarkers Between Those With And Without Diabetic Retinopathy

OBJECTIVE To compare the serum proangiogenic biomarkers in diabetic patients suffering from with and without diabetic retinopathy (DR). STUDY DESIGN An observational study. PLACE AND DURATION OF STUDY Arif Memorial Teaching Hospital, Lahore, Pakistan and Institute of Molecular Biology and Biotechnology/Centre for Research in Molecular Medicine, The University of Lahore, Lahore, Pakistan, from March to December 2017. METHODOLOGY Forty patients with DR were included in group A and 15 patients without retinopathy (controls) were included in group B. Twelve serum pro-angiogenic biomarkers [Angiopoietin 2, Human Growth Factor (HGF), Epidermal Growth Factor (EGF), Fibroblast Growth Factor (FGF), Placental Growth Factor (PLGF), Vascular Endothelial Growth Factor-A and C (VEGF-A and VEGF-C), Bone Morphogenetic Protein 9 (BMP9), Follistatin, Leptin, Interleukin-8 (IL8), Endothelin (ET)] were analysed by xMAP flow cytometry technique, results were compared between the two groups and statistical analysis was done using Mann-Whitney U test. RESULTS Serum ET, Follistatin and EGF were significantly raised in group A as compared to group B having p-values of 0.001, <0.001, and 0.033, respectively. Serum BMP9, Leptin, HGF, FGF and VEGF-C had p <0.001, 0.023, 0.020, and 0.009, respectively and were higher in group B than group A. CONCLUSION Serum ET, Follistatin and EGF were significantly higher in DR patients as compared to those without DR and should be considered to be significant biomarkers of retinal complications in diabetes mellitus.

Molecular Characterization, Structural Modeling, and Evaluation of Antimicrobial Activity of Basrai Thaumatin-Like Protein against Fungal Infection

A thaumatin-like protein gene from Basrai banana was cloned and expressed in Escherichia coli. Amplified gene product was cloned into pTZ57R/T vector and subcloned into expression vector pET22b(+) and resulting pET22b-basrai TLP construct was introduced into E. coli BL21. Maximum protein expression was obtained at 0.7 mM IPTG concentration after 6 hours at 37°C. Western blot analysis showed the presence of approximately 20 kDa protein in induced cells. Basrai antifungal TLP was tried as pharmacological agent against fungal disease. Independently Basrai antifungal protein and amphotericin B exhibited their antifungal activity against A. fumigatus; however combined effect of both agents maximized activity against the pathogen. Docking studies were performed to evaluate the antimicrobial potential of TLP against A. fumigatus by probing binding pattern of antifungal protein with plasma membrane ergosterol of targeted fungal strain. Ice crystallization primarily damages frozen food items; however addition of antifreeze proteins limits the growth of ice crystal in frozen foods. The potential of Basrai TLP protein, as an antifreezing agent, in controlling the ice crystal formation in frozen yogurt was also studied. The scope of this study ranges from cost effective production of pharmaceutics to antifreezing and food preserving agent as well as other real life applications.

Binding properties of beetal recombinant caprine growth hormone to Bovidae liver microsomal membranes

The aim of the study was to illustrate the radio-receptor assay of beetal recombinant caprine growth hormone (rcGH). Tracer ( 125 I-rcGH) was prepared by iodinating beetal rcGH with iodine-125 and its biological activity was analyzed by rabbit anti-rcGH antibodies. Liver microsomal membranes of the Bovidae species (caprine, ovine and bovine) were prepared to study the binding properties of beetal rcGH. The tracer binding was dependent on receptor protein concentration, tracer counts, temperature, time of incubation and assay pH. The maximum percentage specific binding of the tracer to the microsomal membrane was 45% in 32 h at 4°C. In cross-reactive study, human GH competed and displaced the 125 I-rcGH by binding effectively to the cGH receptor. Scatchard analysis of the rcGH binding suggested a single class of binding site to the caprine microsomal membrane with an affinity of 337.1 ± 82.94 × 10 9 M -1 and capacity of 57.61 ± 4.23 fmol mg -1 while rcGH binding affinity and capacity to the ovine and bovine receptor protein showed 365.4 ± 66.82 × 10 9 M -1 , 57.69 ± 3.23 (fmol mg -1 ) and 392.6 ± 56.25 × 10 9 M -1 , 56.8 ± 2.56 (fmol mg -1 ) respectively. This study provides data for beetal rcGH interaction with microsomal membrane that shall be beneficial to study hormone receptor interactions of other Bovidae species. Keywords: Beetal recombinant caprine growth hormone, Bovidae, iodine-125, microsomal membrane, receptor protein African Journal of Biotechnology , Vol 13(30) 3081-3091