RESUMEN
The Streptomyces coelicolor fab (fatty acid biosynthesis) gene cluster (fabD-fabH-acpP-fabF) is cotranscribed to produce a leaderless mRNA transcript. One of these genes, fabH, encodes a ketoacyl synthase III that is essential to and is proposed to be responsible for initiation of fatty acid biosynthesis in S. coelicolor.
Asunto(s)
3-Oxoacil-(Proteína Transportadora de Acil) Sintasa/genética , 3-Oxoacil-(Proteína Transportadora de Acil) Sintasa/metabolismo , Ácidos Grasos/biosíntesis , Genes Esenciales , Streptomyces/enzimología , Medios de Cultivo , Ácidos Grasos/genética , Eliminación de Gen , Genes Bacterianos , Familia de Multigenes , Streptomyces/genética , Streptomyces/crecimiento & desarrolloRESUMEN
A chromosomal DNA fragment from Streptomyces antibioticus ATCC11891 was isolated by its ability to stimulate actinorhodin and undecylprodigiosin biosynthesis in Streptomyces lividans TK21. This fragment includes two open reading frames, whose deduced translated products resemble enzymes involved in sulfur metabolism (ORF1) and LysR-type transcriptional regulators (ORF2). The cloning of the promoter region of ORF2 (abaB) in high copy number led to overproduction of both antibiotics suggesting that this phenotype might well be due to titration by this region of one or more proteins. Southern blot analysis revealed that abaB gene is highly conserved among all streptomycetes tested.
Asunto(s)
Genes Fúngicos/genética , Regiones Promotoras Genéticas/fisiología , Streptomyces/genética , Streptomyces/metabolismo , Antibacterianos/biosíntesis , Secuencia de Bases , Southern Blotting , Cromatografía Líquida de Alta Presión , Clonación Molecular , ADN de Hongos/genética , Dosificación de Gen , Regulación Fúngica de la Expresión Génica/genética , Datos de Secuencia Molecular , Oleandomicina/biosíntesis , Sistemas de Lectura Abierta/genética , Plásmidos , Mapeo Restrictivo , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Transcripción Genética/genéticaRESUMEN
The Rhizobium leguminosarum biovar viciae nodulation protein NodO is partially homologous to haemolysin of Escherichia coli and, like haemolysin, is secreted into the growth medium. The NodO protein can be secreted by a strain of E. coli carrying the cloned nodO gene plus the haemolysin secretion genes hlyBD, in a process that also requires the outer membrane protein encoded by tolC. The related protease secretion genes, prtDEF, from Erwinia chrysanthemi also enable E. coli to secrete NodO. The Rhizobium genes encoding the proteins required for NodO secretion are unlinked to nodO and are unlike other nod genes, since they do not require flavonoids or NodO for their expression. Although proteins similar to NodO were not found in rhizobia other than R. leguminosarum bv. viciae, several rhizobia and an Agrobacterium strain containing the cloned nodO gene were found to have the ability to secrete NodO. These observations indicate that a wide range of the Rhizobiaceae have a protein secretion mechanism analogous to that which secretes haemolysin and related toxins and proteases in the ENterobacteriaceae.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Unión al Calcio , Rhizobium leguminosarum/metabolismo , Proteínas Bacterianas/genética , Clonación Molecular , Medios de Cultivo , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Escherichia coli/metabolismo , Genes Bacterianos , Proteínas Hemolisinas/metabolismo , Rhizobiaceae/genética , Rhizobiaceae/metabolismo , Rhizobium leguminosarum/genéticaRESUMEN
The presence of a resident T lymphocyte population in the meninges of normal SJL/J mice has been detected by the use of the T cell-specific mitogen concanavalin A. Optimal conditions for [3H]thymidine incorporation were studied. An antigen-specific meningeal T cell proliferative response in SJL/J mice, primed by intracerebral inoculation of Theiler's murine encephalomyelitis virus, was also detected. This response indicated that leptomeningeal mononuclear cell infiltrations are involved in the immune response that triggers the demyelinating disease.
Asunto(s)
Virus Maus Elberfeld/inmunología , Meninges/inmunología , Linfocitos T/inmunología , Animales , Antígenos/inmunología , Separación Celular , Concanavalina A/farmacología , Enfermedades Desmielinizantes/etiología , Activación de Linfocitos , Ratones , Timidina/metabolismoRESUMEN
The spleen T cell proliferative response of SJL/J mice primed by intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) was characterized in vitro. A dose-response [3H]thymidine incorporation was found with TMEV, but not with unrelated viruses. The maximum response was obtained at doses of 5 X 10(5) cells per well with cultures of 96 h duration. Viral capsid proteins VP1 and VP2 carried the antigenic determinants for the T cell response, VP3 playing no role in the in vitro cellular immune response. The antibody synthesis showed the same antigenic specificity as the cellular one, as only antibodies against VP1 and VP2 could be found in the sera of the immunized animals.