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We have determined the nucleotide sequence of a region of 656 nucleotides comprising the 31 gene of bacteriophage T4. The coding region consisted of 333 nucleotides directing the synthesis of a polypeptide of 111 amino acids, with a calculated molecular weight of 12,060. The upstream sequence contains the consensus sequences for T4 early and two middle promoters. The downstream sequence contains the consensus sequence for T4 late promoter and the inverted repeats. In addition, there are two incomplete open reading frames in the sequenced region.  相似文献   

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We have determined the complete DNA sequence of the short unique region in the genome of herpes simplex virus type 1, strain 17, and have interpreted it in terms of messenger RNAs and encoded proteins. The sequence contains variable regions whose length differs between DNA clones. The clones used for most of the analysis gave a short unique length of 12,979 base-pairs. We consider that this region contains 12 genes, which are expressed by mRNAs which have separate promoters, but may share 3'-termination sites, so that all but two mRNAs belong to one of four 3'-coterminal "families": 79% of the sequence is considered to be polypeptide coding. One pair of genes has an extensive out-of-frame overlap of coding sequences. The proteins encoded in the short unique region include two immediate-early species, two virion surface glycoproteins, and a DNA-binding species. Six of the genes have little or no previous characterization. From the nature of the amino acid sequences predicted for their encoded proteins, we deduce that several of these proteins may be membrane-associated.  相似文献   

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The nucleotide sequence running from the genetic left end of bacteriophage T7 DNA to within the coding sequence of gene 4 is given, except for the internal coding sequence for the gene 1 protein, which has been determined elsewhere. The sequence presented contains nucleotides 1 to 3342 and 5654 to 12,100 of the approximately 40,000 base-pairs of T7 DNA. This sequence includes: the three strong early promoters and the termination site for Escherichia coli RNA polymerase: eight promoter sites for T7 RNA polymerase; six RNAase III cleavage sites; the primary origin of replication of T7 DNA; the complete coding sequences for 13 previously known T7 proteins, including the anti-restriction protein, protein kinase, DNA ligase, the gene 2 inhibitor of E. coli RNA polymerase, single-strand DNA binding protein, the gene 3 endonuclease, and lysozyme (which is actually an N-acetylmuramyl-l-alanine amidase); the complete coding sequences for eight potential new T7-coded proteins; and two apparently independent initiation sites that produce overlapping polypeptide chains of gene 4 primase. More than 86% of the first 12,100 base-pairs of T7 DNA appear to be devoted to specifying amino acid sequences for T7 proteins, and the arrangement of coding sequences and other genetic elements is very efficient. There is little overlap between coding sequences for different proteins, but junctions between adjacent coding sequences are typically close, the termination codon for one protein often overlapping the initiation codon for the next. For almost half of the potential T7 proteins, the sequence in the messenger RNA that can interact with 16 S ribosomal RNA in initiation of protein synthesis is part of the coding sequence for the preceding protein. The longest non-coding region, about 900 base-pairs, is at the left end of the DNA. The right half of this region contains the strong early promoters for E. coli RNA polymerase and the first RNAase III cleavage site. The left end contains the terminal repetition (nucleotides 1 to 160), followed by a striking array of repeated sequences (nucleotides 175 to 340) that might have some role in packaging the DNA into phage particles, and an A · T-rich region (nucleotides 356 to 492) that contains a promoter for T7 RNA polymerase, and which might function as a replication origin.  相似文献   

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