Nucleotide sequence of bacteriophage T4 uvsY gene

We have determined the nucleotide sequence of a 1001-bp region comprising the uvsY gene of bacteriophage T4. An open reading frame of 420 base pairs was found to encode the uvsY gene product. The uvsY gene comprised a 140-amino acid protein with ATG (methionine) as the initiation codon, which is consistent with the molecular weight determined by SDS-polyacrylamide gel electrophoresis. The uvsY gene was oriented in the direction of the early genes and a sequence common to the middle promoter consensus was found in the 5'-upstream region.     

铜绿假单胞菌噬菌体PaP3全基因组在感染宿主菌PA3过程中的分时期表达研究

目的明确铜绿假单胞菌噬菌体PaP3在感染宿主菌PA3后其全基因组的分时期表达模式。方法利用基因芯片检测噬菌体PaP3在感染宿主菌PA3后不同时间(5 min,10 min,20 min,30 min,80 min)其全基因组(含71个预测的ORF)在转录水平的表达谱变化,并进行非监督层次聚类(hierarchical clustering)分析。利用蛋白质合成抑制剂氯霉素(Cm)和DNA复制抑制剂磷酸乙酸(PAA)实验确定PaP3全基因组的分时期表达情况。结果根据时间表达模式的不同,PaP3全基因组可分为3大类:15个早期基因(ORF 71-57)、35个中期基因(ORF 56-22)及21个晚期基因(ORF 21-1)。在PaP3基因组结构中,这3类基因各自串联分布且可能受不同的操纵子调控。结论 PaP3感染过程中其早期、中期及晚期基因随时间有序表达,为深入了解噬菌体基因表达模式及生命复制周期奠定基础,并为了解噬菌体与宿主及机体免疫系统的的相互作用提供了基础。     

An analysis of DNA repair and recombination functions of bacteriophage T4 by means of suppressors: the role of das

Previous studies have indicated that the bacteriophage T4 das mutations partially suppressed the DNA replication defects in gene 46 and 47 mutations. Here it is shown that the das mutation also suppresses the DNA repair defects but not the DNA replication defects of the uvsX and uvsY mutations. In contrast, the das mutation suppressed both the DNA replication and repair defects of gene 46 and 47 mutations. These characteristics of das as well as those of the other suppressors, including uvsW(dar) and two new suppressors sur and uvsU have been used for the analysis of the DNA repair pathway. Based on the functions of these suppressors, a sequence in which the gene products in this pathway might act is suggested.     

Transcription and translation mapping of the 13 genes in the vaccinia virus HindIII D fragment

The vaccinia virus HindIII D fragment is 160,060 bp in length and encodes 13 complete open reading frames [Niles et al. (1986) Virology 153, 96-112; S. L. Weinrich and D. E. Hruby (1986). Nucleic Acids Res. 14, 3003-3016]. We have employed a two-step Northern hybridization protocol using single-stranded DNA probes from M13 recombinants in order to identify the mRNA products from the 13 genes. Six of these genes are expressed only at early times after infection; six are transcribed only at late times; one gene is expressed at both early and late times after virus infection. The D11 gene is transcribed into two late mRNA species, one full-length and the other derived from the 3' one-third of the coding sequence. Translation of hybrid-selected mRNA was carried out in an attempt to identify the protein products encoded by each mRNA. Protein products were found for each early gene but translation was successful for only two of the eight late mRNAs. With the completion of the physical map it is apparent that the early and late genes in the HindIII D fragment are arranged in order to minimize potential interference caused by the expression of closely packed viral genes.     

A new suppressor of mutations in the DNA repair-recombination genes of bacteriophage T4: sur

A new mutation designated sur was isolated as a suppressor of a mutation in the uvsX gene of T4 phage. Unlike the other suppressors of mutations in genes involved in DNA repair and recombination, sur has a wide range, suppressing both DNA repair and replication defects in mutations in genes uvsX, uvsY, 46, 47, and 59. However, its suppressor functions may be confined to the uvsX-uvsY DNA repair pathway since sur did not suppress a mutation in the denV gene. The sur mutation results in an increased degradation of host DNA to an acid-soluble form, but this increase was blocked by a mutation in gene 46 (nuclease) indicating that the sur function is involved in an earlier step in the degradation of host DNA. This increased degradation of host DNA might be a reflection of a compensatory increase in an alternate DNA repair activity in the [sur] mutant.