RESUMEN
Exoglucanase Cex from Cellulomonas fimi is a glycoprotein [Langsford et al., J. Gen. Microbiol. 130 (1984) 1367-1376]. Cex produced by Streptomyces lividans from the cloned cex gene is also glycosylated. The extent and nature of glycosylation are similar for Cex from both organisms. The glycosylation affords protection against proteolysis for the enzymes from both organisms when they are bound to cellulose, but not in solution. The ability to glycosylate cloned gene products enhances the utility of Streptomyces as a host for the production of heterologous polypeptides.
Asunto(s)
Actinomycetales/enzimología , Streptomyces/metabolismo , beta-Glucosidasa/metabolismo , Clonación Molecular , Electroforesis en Gel de Poliacrilamida , Glucano 1,3-beta-Glucosidasa , Glicosilación , Hidrólisis , PlásmidosRESUMEN
A WF9 strain of maize with the RD subtype of the S male-sterile cytoplasm (CMS-S) was converted to the inbred M825 nuclear background by recurrent backcrossing. The organization of the mitochondrial genomes of the F1 and succeeding backcross progenies was analyzed and compared with the progenitor RD-WF9 using probes derived from the S1 and S2 mitochondrial episomes, and probes containing the genes for cytochrome c oxidase subunit I (coxI), cytochrome c oxidase subunit II (coxII) and apocytochrome b (cob). Changes in mitochondrial DNA (mtDNA) organization were observed for S1-, S2-, and coxI-homologous sequences that involve loss of homologous restriction enzyme fragments present in the RD-WF9 progenitor. With the coxI probe, the loss of certain fragments was accompanied by the appearance of a fragment not detectable in the progenitor. The changes observed indicate the effect of the nuclear genome on the differential replication of specific mitochondrial subgenomic entities.
Asunto(s)
ADN Mitocondrial/genética , Genes de Plantas , Zea mays/genética , Apolipoproteínas B/genética , Apolipoproteínas B/metabolismo , Cruzamientos Genéticos , Enzimas de Restricción del ADN/metabolismo , Complejo IV de Transporte de Electrones/genética , Complejo IV de Transporte de Electrones/metabolismo , Genotipo , Mitocondrias/enzimología , Reproducción/genética , Homología de Secuencia de Ácido Nucleico , Zea mays/enzimologíaRESUMEN
The mitochondrial genome organizations of a number of independent culture-derived fertile CMS-S revertants with the nuclear genotype W182BN were compared to spontaneous field revertants with the genotypes WF9, M825/Oh07 and 38-11. Regions of the genome around sequences homologous to the terminal repeats of the linear S1 and S2 episomes characteristic of CMS-S mitochondria were used as hybridization probes on Southern blots of BamHI and SalI digested mitochondrial DNA. The results obtained suggest that the nuclear, not the cytoplasmic, genotype of the parent plant affects the type of novel mitochondrial DNA organization found in the revertant. The DNA reorganization during reversion from CMS-S in tissue culture appears to be similar to that observed in spontaneous revertants obtained during the normal plant life-cycle. Unlike the situation for reversion from CMS-T, no common DNA sequence or reading frame appeared to be lost or disrupted in revertants.