Expression of synthetic Phytochelatin EC20 in E. Coli increases its biosorption capacity and cadmium resistance / Expressão de Fitoquelatina EC20 sintética em E. Coli aumenta sua capacidade de biossorção e resistência ao cádmio

In this study E. coli recombinant clones that express the EC20 synthetic phytochelatin intracellularly were constructed. The increasement of Cd2+ biosorption capacity, and, also, the increasement of resistance to this toxic metal were analyzed. A gene that encodes the synthetic phytochelatin EC20 wassynthesized in vitro. The EC20 synthetic gene was amplified by PCR, inserted into the DNA cloning vectors pBluescript®KS+ and pGEM®-TEasy, and also into the expression vectors pTE [pET-28(a)® derivative] and pGEX-T4-2®. The obtained recombinant plasmids were employed for genetic transformation of E. coli: pBsKS-EC20 and pGEM-EC20, they were introduced into DH10B and DH5α strains, similarly to pTE-EC20 and pGEX-EC20 that were introduced into BL21 strain. The EC20 expression was confirmed by SDS-PAGE analysis. The recombinant clones' resistances to Cd2+ were determined by MIC analyses. The MIC for Cd2+ of DH10B/pBKS-EC20 and DH10B/pGEM-EC20 were 2.5 mM (EC20 induced), and 0.312 mM (EC20 repressed);respectively, 16 and 2 times higher than the control DH10B/pBsKS (0.156 mM). The MIC for Cd2+of BL21/pTE-EC20 was 10.0 mM (EC20 induced) and 2.5 mM (EC20 repressed), compared with the control BL21/pTE which was only 1.25 mM. Analysis of ICP-AES showed that BL21/pGEX-EC20, after growth on the condition of EC20 expression, absorbed 37.5% of Cd2+, and even when cultured into the non-induction condition of EC20 expression, it absorbed 11.5%.These results allow the conclusion thatrecombinant E. coli clonesexpressing the synthetic phytochelatin EC20 show increased capacity for Cd2+ biosorption and enhanced resistance to this toxic ion.

Foram construídos clones recombinantes de E. coli que expressam intracelularmente a fitoquelatina sintética EC20. Foi analisado o aumento na capacidade de biossorção de Cd2+ e o aumento da resistência a este metal tóxico.Foi sintetizado in vitro um gene codificante da fitoquelatina sintética EC20. O gene EC20 sintético foi amplificado por PCR, inserido nos vetores de clonagem pBluescript®KS+ e pGEM®-TEasy, e nos vetores de expressão pTE [derivado de pET-28(a)®] e pGEX-T4-2®. Os plasmídeos recombinantes foram empregados na transformação genética de E. coli: pBsKS-EC20 e pGEM-EC20 foram introduzidos nas linhagens DH10B e DH5α; e, pTE-EC20 e pGEX-EC20 na linhagem BL21-DE3. A expressão EC20 foi analisada por SDS-PAGE. As resistências a Cd2+ dos clones recombinantes foram determinadas por análises de MIC.A MIC para Cd2+ de DH10B/pBsKS-EC20 e de DH10B/pGEM-EC20 foi 2,5 mM (EC20induzido) e 0,312 mM (EC20 reprimido); respectivamente, 16 e 2 vezes superiores às do controle DH10B/pBsKS (0,156 mM). A MIC para Cd2+ de BL21/pTE-EC20 foi 10,0 mM (EC20 induzido) e 2,5 mM (EC20 reprimido), comparado a do controle BL21/pTE que foi apenas 1,25 mM. A análise de ICP-AES mostrou que BL21/pGEX-EC20, após crescimento na condição de expressão de EC20, absorveu 37,5% de Cd2+e, mesmo quando cultivado na condição de não-indução de expressão EC20, absorveu 11,5% de Cd2+. Estes resultados permitem a conclusão de que os clones recombinantes de E. coli que expressam a fitoquelatina sintética EC20 apresentam aumento da capacidade de biossorção de Cd2+ e de resistência a este íon tóxico.

Avaliação do extrato etanólico de casca de Punica granatum (romã) na diminuição da replicação viral do BoHV-1 Colorado em embriões murinos experimentalmente infectados / Evaluation of ethanol extract of Punica granatum (Pomegranate) peel decrease in viral replication of BoHV-1 in Colorado murine embryos experimentally infected

O objetivo do trabalho foi avaliar a diminuição da replicação viral (BoHV-1 Colorado) em embriões murinos após tratamento do extrato etanólico da casca de Punica granatum (EEPg). Camundongos fêmeas Swiss com idade entre 6 e 8 semanas foram superovuladas com 0,2 mL a 5 UI de hormônios (eCG e hCG), e acasaladas com machos da mesma idade. Após 18 horas, as fêmeas sofreram eutanásia em câmara de CO2 e, através de abertura no peritônio, os zigotos foram coletados e lavados com solução de pronase 0,5%.Os zigotos foram divididos em quatro grupos: G1 (controle), G2 (expostos aos vírus BoHV-1 Colorado a 108 TCID50/mL), G3 (expostos ao EEPg) e G4 (expostos aos vírus e ao EEPg). Os grupos foram mantidos a 37,5ºC em meio TCM199 (100µL) com 10% de soro fetal bovino em estufa a 5% de CO2 e 95% de umidade. Após 24 h, analisamos a taxa de clivagem (teste exato de Fisher; p<0,05), a morfologia (por microscopia óptica), a nested-PCR e a titulação dos embriões em cocultura com células MDBK após mais 72 h do tratamento (teste de Mann-Whitney; p<0,05) e microscopia eletrônica de transmissão (ME). Os embriões murinos tratados com EEPg apresentaram resultados satisfatórios: sem alterações morfológicas, taxa de clivagem semelhante ao controle e, apesar da detecção da presença do vírus pela nested-PCR e ME, houve diminuição do título viral após tratamentos com esse extrato, o que sugere interferência desse tratamento no ciclo viral do BoHV-1 Colorado sem alterar o desenvolvimento dos embriões.(AU)

The aim of this study was to evaluate the reduction of viral replication (Colorado BoHV-1) in murine embryos after the treatment of ethanol extract of Punica granatum peel (PgEE). Swiss female mice aged 6 to 8 weeks were superovulated with 0.2 mL of the 5 UI hormones (eCG and hCG) and mated with males of the same age. After 18 hours, the females were euthanized in a CO2 chamber, and through the opening in the peritoneum, zygotes were collected and washed with 0.5% pronase solution. The zygotes were divided into four groups: G1 (control), G2 (exposed to the virus Colorado BoHV -1 to 108 TCID50/mL), G3 (exposed to PgEE) and G4 (exposed to the virus and to PgEE). The groups were maintained at 37.5ºC in TCM199 (100 mL) with 10% fetal bovine serum in an incubator at 5% CO2 and 95% humidity. After 24 h, we analyzed the cleavage rate (Fisher's exact test; p<0.05), the morphology (by light microscopy), the nested-PCR and the titration of embryos in co-culture with MDBK cells after over 72 h of treatment (Mann-Whitney test; p<0.05) and transmission electron microscopy (TEM). The murine embryos treated with PgEE showed satisfactory results: no morphological changes, cleavage rate similar to controls, despite the detection of the presence of virus by nested PCR and TEM, there was a decrease of the viral titer after the treatment with this extract, which suggests interference of this treatment in the viral cycle BoHV-1 Colorado without altering the embryo development.(AU)

Synthetic phytochelatin surface display in Cupriavidus metallidurans CH34 for enhanced metals bioremediation.

This work describes the effects of the cell surface display of a synthetic phytochelatin in the highly metal tolerant bacterium Cupriavidus metallidurans CH34. The EC20sp synthetic phytochelatin gene was fused between the coding sequences of the signal peptide (SS) and of the autotransporter ß-domain of the Neisseria gonorrhoeae IgA protease precursor (IgAß), which successfully targeted the hybrid protein toward the C. metallidurans outer membrane. The expression of the SS-EC20sp-IgAß gene fusion was driven by a modified version of the Bacillus subtilis mrgA promoter showing high level basal gene expression that is further enhanced by metal presence in C. metallidurans. The recombinant strain showed increased ability to immobilize Pb(2+), Zn(2+), Cu(2+), Cd(2+), Mn(2+), and Ni(2+) ions from the external medium when compared to the control strain. To ensure plasmid stability and biological containment, the MOB region of the plasmid was replaced by the E. coli hok/sok coding sequence.

Autolytic Mycobacterium leprae Hsp65 fragments may act as biological markers for autoimmune diseases.

Investigating the proteolytic activity of the recombinant Mycobacterium leprae Heat Shock Protein of 65 kDa (rHsp65), chaperonin 2 (cpn2), we observed that it displays high instability. The fragmentation process starts at the C-terminus followed by progressive degradation of the N-terminus, which leads to a stable fragment comprising the middle region of the molecule. Urea was able to prevent autolysis, probably due to its denaturing action, while EDTA increased degradation levels indicating the need for metal ions. Peptides originated from autolysis were purified and analyzed by mass spectrometry, generating a continuous map. Since the bacteria and mammalian Hsp60 are known to be targets of the immune response and have been implicated in autoimmune diseases and chronic inflammation, the in vivo effect of rHsp65 peptides was evaluated in the spontaneous Systemic Lupus Erythematosus (SLE) model developed by the (NZB/NZW)F(1) mouse hybrids, and their individual anti-rHsp65 IgG2a/IgG1 antibody titer ratio was determined. The results showed orientation toward a T(H)1 responsiveness, and the treatment with the rHsp65 peptides diminished the environmental variance of the survival time of treated animals. These results outline the fact that environmental factors may also act through the modified stability expression of Heat Shock Proteins intervening during autoimmune processes.

Autolytic Mycobacterium leprae Hsp65 fragments may act as biological markers for autoimmune diseases

Investigating the proteolytic activity of the recombinant Mycobacterium leprae Heat Shock Protein of 65 kDa (rHsp65), chaperonin 2 (cpn2), we observed that it displays high instability. The fragmentation process starts at the C-terminus followed by progressive degradation of the N-terminus, which leads to a stable fragment comprising the middle region of the molecule. Urea was able to prevent autolysis, probably due to its denaturing action, while EDTA increased degradation levels indicating the need for metal ions. Peptides originated from autolysis were purified and analyzed by mass spectrometry, generating a continuous map. Since the bacteria and mammalian Hsp60 are known to be targets of the immune response and have been implicated in autoimmune diseases and chronic inflammation, the in vivo effect of rHsp65 peptides was evaluated in the spontaneous Systemic Lupus Erythematosus (SLE) model developed by the (NZB/NZW)F1 mouse hybrids, and their individual anti-rHsp65 IgG2a/IgG1 antibody titer ratio was determined. The results showed orientation toward a TH1 responsiveness, and the treatment with the rHsp65 peptides diminished the environmental variance of the survival time of treated animals. These results outline the fact that environmental factors may also act through the modified stability expression of Heat Shock Proteins intervening during autoimmune processes.

A metal-repressed promoter from gram-positive Bacillus subtilis is highly active and metal-induced in gram-negative Cupriavidus metallidurans.

A synthetic version of the metal-regulated gene A (mrgA) promoter from Bacillus subtilis, which in this Gram-positive bacterium is negatively regulated by manganese, iron, cobalt, or copper turned out to promote high level of basal gene expression that is further enhanced by Co(II), Cd(II), Mn(II), Zn(II), Cu(II), or Ni(II), when cloned in the Gram-negative bacterium Cupriavidus metallidurans. Promoter activity was monitored by expression of the reporter gene coding for the enhanced green fluorescent protein (EGFP), and cellular intensity fluorescence was quantified by flow cytometry. Expression levels in C. metallidurans driven by the heterologous promoter, here called pan, ranged from 20- to 53-fold the expression level driven by the Escherichia coli lac promoter (which is constitutively expressed in C. metallidurans), whether in the absence or presence of metal ions, respectively. The pan promoter did also function in E. coli in a constitutive pattern, regardless of the presence of Mn(II) or Fe(II). In conclusion, the pan promoter proved to be a powerful tool to express heterologous proteins in Gram-negative bacteria, especially in C. metallidurans grown upon high levels of toxic metals, with potential applications in bioremediation.

A novel system of genetic transformation allows multiple integrations of a desired gene in Saccharomyces cerevisiae chromosomes.

Increasing industrial competitiveness and productivity demand that recombinant yeast strains, used in many different processes, be constantly adapted and/or genetically improved to suit changing requirements. Among yeasts, Saccharomyces cerevisiae is the best-studied organism, and the most frequently employed yeast in industrial processes. In the present study, laboratory strains and industrial S. cerevisiae strains were stably transformed with a novel vector containing the glucoamylase cDNA of Aspergillus awamori flanked by delta-sequences (deltaGlucodelta), and lacking a positive selection marker. Co-transformation with known plasmids allowed selection by auxotrophic complementation of the leu2 mutation and/or geneticin resistance (G418). In all cases, several copies of the deltaGlucodelta vector were inserted into the genome of the yeast cell without selective pressure, showing 100% stability after 80 generations. Transformation frequency of the new vector was similar for S. cerevisiae laboratory strains and industrial wild-type S. cerevisiae strains. This novel genetic transformation system is versatile and suitable to introduce several stable copies of a desired expression cassette into the genome of different S. cerevisiae yeast strains.