The Escherichia coli DNA polymerase III holoenzyme contains both products of the dnaX gene, tau and gamma, but only tau is essential.

作者: A Blinkova , C Hervas , P T Stukenberg , R Onrust , M E O'Donnell

DOI: 10.1128/JB.175.18.6018-6027.1993

关键词: Protein subunitdnaXStop codonMolecular biologyBiologyBiochemistryGenePolymeraseDNA polymeraseGamma subunitFrameshift mutation

摘要: Abstract The replicative polymerase of Escherichia coli, DNA III, consists a three-subunit core plus seven accessory subunits. Of these seven, tau and gamma are products one replication gene, dnaX. The shorter is created from within the reading frame by programmed ribosomal -1 frameshift over codons 428 429 followed stop codon in new frame. Two temperature-sensitive mutations available 2016(Ts) mutation altered both changing 118 glycine to aspartate; 36(Ts) affected activity only because it 601 (from glutamate lysine). Evidence which indicates that, two proteins, longer essential includes following. (i) lethal allele, overproduction wild-type cannot restore its growth. (ii) An allele produced could be substituted for chromosomal but gamma-only not substitute dnaX haploid state. Thus, subunit essential, suggesting that can usual function(s) gamma. Consistent with results, we found functional was assembled nine pure subunits absence subunit. However, possibility cells growing without gamma, proteolysis form gamma-like product amounts below Western blot (immunoblot) sensitivity level excluded.

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