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1.
Acta Leprol ; 7 Suppl 1: 203-7, 1989.
Artigo em Inglês | MEDLINE | ID: mdl-2503991

RESUMO

Requisite to a detailed understanding of the molecular basis of bacterial pathogenesis is a genetic system which allows for the transfer, mutation, and expression of specific genes. Genetic analysis of mycobacteria has been exceedingly difficult since the mycobacteria grow slowly and no natural efficient method of gene transfer within the pathogenic has thus far been found. Using a molecular genetic approach, we have developed both the vectors and the methodology for efficient gene transfer in the mycobacteria. Initially, a novel of type of mycobacteriophage vector was developed, termed a shuttle phasmid. This hybrid shuttle vector replicates in Escherichia coli as a plasmid and in mycobacteria as a phage, capable of introducing foreign DNA into a wide variety of mycobacterial species. A set of shuttle phasmids, constructed from a temperate mycobacteriophage, retained their ability to lysogenize their mycobacterial hosts and could thus introduce foreign DNA stably into mycobacterial cells. An E. coli gene conferring kanamycin-resistance was cloned into these vectors and shown to express in the mycobacteria, thus providing the first selectable marker gene for subsequent genetic studies. Using kanamycin-resistance gene as a selection, the M. fortuitum plasmid pAL5000 replicon, and electroporation; a plasmid transformation system has been developed for both M. smegmatis and BCG. We now plan to use these phage and plasmid systems to analyze, genetically, the virulence attributes of the pathogenic mycobacteria. In addition, by introducing and expressing foreign antigens in BCG, we hope to develop a novel recombinant multi-vaccine vehicle capable of conferring immunity to a variety of bacterial, viral, and parasitic pathogens.


Assuntos
Mycobacterium/genética , Vacina BCG/isolamento & purificação , Vacinas Bacterianas/isolamento & purificação , Genes Bacterianos , Vetores Genéticos , Mycobacterium/imunologia , Mycobacterium/patogenicidade , Plasmídeos , Transformação Genética , Virulência
2.
Proc Natl Acad Sci U S A ; 85(18): 6987-91, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2842799

RESUMO

Requisite to a detailed understanding of the molecular basis of bacterial pathogenesis is a genetic system that allows for the transfer, mutation, and expression of specific genes. Because of the continuing importance of tuberculosis and leprosy worldwide, we initiated studies to develop a genetic system in mycobacteria and here report the use of two complementary strategies to introduce and express selectable genetic markers. First, an Escherichia coli cosmid was inserted into the temperate mycobacteriophage L1, generating shuttle phasmids replicating as plasmids in E. coli and phage capable of lysogenizing the mycobacterial host. These temperate shuttle phasmids form turbid plaques on Mycobacterium smegmatis and, upon lysogenization, confer resistance to superinfection and integrate within the mycobacterial chromosome. When an L1 shuttle phasmid containing a cloned gene conferring kanamycin resistance in E. coli was introduced into M. smegmatis, stable kanamycin-resistant colonies--i.e., lysogens--were obtained. Second, to develop a plasmid transformation system in mycobacteria, M. fortuitum/E. coli hybrid plasmids containing mycobacterial and E. coli replicons and a kanamycin-resistance gene were constructed. When introduced into M. smegmatis or BCG (Mycobacterium tuberculosis typus bovinus var. Bacille-Calmette-Guérin) by electroporation, these shuttle plasmids conferred stable kanamycin resistance upon transformants. These systems should facilitate genetic analyses of mycobacterial pathogenesis and the development of recombinant mycobacterial vaccines.


Assuntos
Regulação da Expressão Gênica , Lisogenia , Mycobacterium/genética , Transformação Bacteriana , Clonagem Molecular , Escherichia coli/genética , Canamicina Quinase , Hanseníase/microbiologia , Métodos , Mycobacterium/enzimologia , Fosfotransferases/genética , Plasmídeos , Tuberculose/microbiologia
3.
J Bacteriol ; 168(1): 72-80, 1986 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3020007

RESUMO

The ability of "Streptomyces lividans" to use the expression signals of genes from Mycobacterium bovis BCG was tested in vivo by using gene fusions. Random DNA fragments from M. bovis BCG were inserted into promoter-probe plasmids in Escherichia coli and in "S. lividans." Comparison with promoter activity detected with random DNA fragments from the respective hosts suggested that "S. lividans" efficiently utilizes a high proportion of mycobacterial promoters, whereas a smaller fraction are expressed, and expressed more weakly, in E. coli. M. bovis BCG DNA fragments were also inserted into the specially constructed translational fusion vector (pIJ688) in "S. lividans." pIJ688 contains the kanamycin phosphotransferase gene (neo) from transposon Tn5, truncated at its amino terminus, as the indicator. The results suggested that "S. lividans" uses M. bovis BCG translational signals almost as efficiently as its own signals. Moreover, several hybrid proteins with an M. bovis BCG-derived amino terminus seemed to be reasonably stable in "S. lividans." These experiments indicate that "S. lividans" may be a suitable host for the expression of Mycobacterium leprae and Mycobacterium tuberculosis genes from their own signals. This is a precondition for the expression of entire biosynthetic pathways, which could be valuable in the production of diagnostic and therapeutic agents. The vectors may also have wider applications for the analysis of gene expression in Streptomyces.


Assuntos
Clonagem Molecular , Genes Bacterianos , Mycobacterium bovis/genética , Regiões Promotoras Genéticas , Streptomyces/genética , Elementos de DNA Transponíveis , Resistência Microbiana a Medicamentos , Escherichia coli/genética , Canamicina/farmacologia , Canamicina Quinase , Fosfotransferases/biossíntese , Fosfotransferases/genética , Biossíntese de Proteínas , Streptomyces/efeitos dos fármacos , Streptomyces/enzimologia
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