Amino acid sequence of the gene 0. 3 protein of bacteriophage T7 and nucleotide sequence of its mRNA
The amino acid sequence of purified gene 0.3 protein of T7, the protein responsible for overcoming host restriction, has been determined. The nucleotide sequence of the 0.3 RNA, the messenger RNA that codes for both the 0.3 protein and the gene 0.4 protein, a T7 protein of unknown function, has also been determined. The 0.3 RNA is 578 nucleotides long, 509 of which are used to code for the 2 proteins. The coding sequences do not overlap, but the termination codon for the 0.3 protein and the presumed initiation codon for the 0.4 protein do overlap in the sequence UAAUG. The 0.3 protein is very acidic: 34 of its 116 amino acids are aspartic or glutamic acid and only 6 are arginine or lysine. The 0.3 protein contains no cysteine. The nucleotide sequence predicts that the 0.4 protein consists of 50 amino acids and contains no histidine or proline. The effects of different mutations indicate that a protein which contains only the first 87 amino acids of the 0.3 protein is unable to prevent host restriction in vivo; one that contains the first 93 amino acids has weak function; and one that has the first 94 amino acids is fully able to prevent host restriction. The apparently critical 94th amino acid is tryptophan. The mutant 0.3 proteins that contain 87 or more amino acids appear to be reasonably stable in vivo, but those that contain 78 or fewer are apparently too unstable to have been observed by gel electrophoresis.
- Research Organization:
- Brookhaven National Lab., Upton, NY
- OSTI ID:
- 6498105
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 256:5
- Country of Publication:
- United States
- Language:
- English
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MESSENGER-RNA
STRUCTURAL CHEMICAL ANALYSIS
AMINO ACIDS
BACTERIOPHAGES
BIOCHEMISTRY
BIOSYNTHESIS
CODONS
ELECTROPHORESIS
ESCHERICHIA COLI
GENES
GENETIC MAPPING
IN VIVO
INHIBITION
MUTANTS
NUCLEOTIDES
PROTEINS
BACTERIA
CARBOXYLIC ACIDS
CHEMISTRY
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MICROORGANISMS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PARASITES
RNA
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VIRUSES
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