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Title
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Primary structure of T4 DNA polymerase. Evolutionary relatedness to eucaryotic and other procaryotic DNA polymerases.
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Authors
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E.K.Spicer,
J.Rush,
C.Fung,
L.J.Reha-Krantz,
J.D.Karam,
W.H.Konigsberg.
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Ref.
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J Biol Chem, 1988,
263,
7478-7486.
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PubMed id
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Abstract
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Bacteriophage T4 gene 43 codes for the viral DNA polymerase. We report here the
sequence of gene 43 and about 70 nucleotides of 5'- and 3'-flanking sequences,
determined by both DNA and RNA sequencing. We have also purified T4 DNA
polymerase from T4 infected Escherichia coli and from E. coli containing a gene
43 overexpression vector. A major portion of the deduced amino acid sequence has
been verified by peptide mapping and sequencing of the purified DNA polymerase.
All these results are consistent with T4 DNA polymerase having 898 amino acids
with a calculated Mr = 103,572. Comparison of the primary structure of T4 DNA
polymerase with the sequence of other procaryotic and eucaryotic DNA polymerases
indicates that T4 DNA polymerase has regions of striking similarity with animal
virus DNA polymerases and human DNA polymerase alpha. Surprisingly, T4 DNA
polymerase shares only limited similarity with E. coli polymerase I and no
detectable similarity with T7 DNA polymerase. Based on the location of specific
mutations in T4 DNA polymerase and the conservation of particular sequences in
T4 and eucaryotic DNA polymerases, we propose that the NH2-terminal half of T4
DNA polymerase forms a domain that carries out the 3'----5' exonuclease activity
whereas the COOH-terminal half of the polypeptide contains the dNTP-binding site
and is necessary for DNA synthesis.
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