PMID:1618804

Citation	Strack, B, Lessl, M, Calendar, R and Lanka, E (1992) A common sequence motif, -E-G-Y-A-T-A-, identified within the primase domains of plasmid-encoded I- and P-type DNA primases and the alpha protein of the Escherichia coli satellite phage P4. J. Biol. Chem. 267:13062-72
Abstract	DNA primases encoded by the conjugative plasmids ColIb-P9 (IncI1), RP4, and R751 (IncP), and the protein of the Escherichia coli satellite phage P4 alpha were shown to contain a common amino acid sequence motif -E-G-Y-A-T-A-. The P4 alpha gene product, required for initiation of phage DNA replication, exhibits primase activity on single-stranded circular DNA templates. This priming activity resembles the enzymatic activity of DNA primases encoded by conjugative plasmids in terms of template utilization and the ability to synthesize primers that can be elongated by DNA polymerase III holoenzyme. The -E-G-Y-A-T-A- motif is part of an extended sequence region most conserved within the primase domains of the four enzymes. Single amino acid substitutions generated in the -E-G-Y-A-T-A- motif of the RP4 TraC2 and the P4 alpha protein affect priming activity, supporting the hypothesis that the conserved sequence motif is part of the active center for primase function. A mutation that eliminates priming activity causes P4 phage to grow poorly and to depend upon the host dnaG primase. Computer analysis identified two additional sequence motifs within the amino acid sequence of the P4 alpha protein: a potential zinc-finger motif and a "type A" nucleotide binding site, both strikingly similar to sequence motifs described in various DNA primases and helicases.
Links	PubMed
Keywords	Amino Acid Sequence; Base Sequence; Coliphages/enzymology; DNA Primase; DNA, Viral; Gene Expression; Molecular Sequence Data; Mutation; Plasmids; Protein Biosynthesis; RNA Nucleotidyltransferases/chemistry; RNA Nucleotidyltransferases/genetics; RNA Nucleotidyltransferases/metabolism; Satellite Viruses/enzymology; Sequence Alignment; Viral Proteins/chemistry; Viral Proteins/genetics; Viral Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPP4:PRIM		GO:0003896: DNA primase activity	ECO:0000314:		F		The P4 alpha protein was placed under the control of the LacI operon in two different recombinant plasmids. A direct assay intended to measure the ability of a primase to initiate synthesis of DNA by measuring the amount of thymine incorporated into the strand was conducted using cells induced to produce the alpha protein via the LacI operon, non-induced cells, and purified alpha protein. The induced cells and purified alpha protein showed high amounts of incorporated thymine, indicating primase activity. The non-induced cells showed no thymine incorporation (Fig 8, p. 13068), demonstrating that the alpha protein has primase activity.	complete CACAO 11889

References

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