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Suppression of ColE1 high-copy-number mutants by mutations in the polA gene of Escherichia coli.
J Bacteriol. 1993 Jan; 175(2):428-37.JB

Abstract

We isolated three Escherichia coli suppressor strains that reduce the copy number of a mutant ColE1 high-copy-number plasmid. These mutations lower the copy number of the mutant plasmid in vivo up to 15-fold; the wild-type plasmid copy number is reduced by two- to threefold. The suppressor strains do not affect the copy numbers of non-ColE1-type plasmids tested, suggesting that their effects are specific for ColE1-type plasmids. Two of the suppressor strains show ColE1 allele-specific suppression; i.e., certain plasmid copy number mutations are suppressed more efficiently than others, suggesting specificity in the interaction between the suppressor gene product and plasmid replication component(s). All of the mutations were genetically mapped to the chromosomal polA gene, which encodes DNA polymerase I. The suppressor mutational changes were identified by DNA sequencing and found to alter single nucleotides in the region encoding the Klenow fragment of DNA polymerase I. Two mutations map in the DNA-binding cleft of the polymerase region and are suggested to affect specific interactions of the enzyme with the replication primer RNA encoded by the plasmid. The third suppressor alters a residue in the 3'-5' exonuclease domain of the enzyme. Implications for the interaction of DNA polymerase I with the ColE1 primer RNA are discussed.

Authors+Show Affiliations

Department of Biology, Indiana University, Bloomington 47405.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8419292

Citation

Yang, Y L., and B Polisky. "Suppression of ColE1 High-copy-number Mutants By Mutations in the polA Gene of Escherichia Coli." Journal of Bacteriology, vol. 175, no. 2, 1993, pp. 428-37.
Yang YL, Polisky B. Suppression of ColE1 high-copy-number mutants by mutations in the polA gene of Escherichia coli. J Bacteriol. 1993;175(2):428-37.
Yang, Y. L., & Polisky, B. (1993). Suppression of ColE1 high-copy-number mutants by mutations in the polA gene of Escherichia coli. Journal of Bacteriology, 175(2), 428-37.
Yang YL, Polisky B. Suppression of ColE1 High-copy-number Mutants By Mutations in the polA Gene of Escherichia Coli. J Bacteriol. 1993;175(2):428-37. PubMed PMID: 8419292.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Suppression of ColE1 high-copy-number mutants by mutations in the polA gene of Escherichia coli. AU - Yang,Y L, AU - Polisky,B, PY - 1993/1/1/pubmed PY - 1993/1/1/medline PY - 1993/1/1/entrez SP - 428 EP - 37 JF - Journal of bacteriology JO - J. Bacteriol. VL - 175 IS - 2 N2 - We isolated three Escherichia coli suppressor strains that reduce the copy number of a mutant ColE1 high-copy-number plasmid. These mutations lower the copy number of the mutant plasmid in vivo up to 15-fold; the wild-type plasmid copy number is reduced by two- to threefold. The suppressor strains do not affect the copy numbers of non-ColE1-type plasmids tested, suggesting that their effects are specific for ColE1-type plasmids. Two of the suppressor strains show ColE1 allele-specific suppression; i.e., certain plasmid copy number mutations are suppressed more efficiently than others, suggesting specificity in the interaction between the suppressor gene product and plasmid replication component(s). All of the mutations were genetically mapped to the chromosomal polA gene, which encodes DNA polymerase I. The suppressor mutational changes were identified by DNA sequencing and found to alter single nucleotides in the region encoding the Klenow fragment of DNA polymerase I. Two mutations map in the DNA-binding cleft of the polymerase region and are suggested to affect specific interactions of the enzyme with the replication primer RNA encoded by the plasmid. The third suppressor alters a residue in the 3'-5' exonuclease domain of the enzyme. Implications for the interaction of DNA polymerase I with the ColE1 primer RNA are discussed. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/8419292/Suppression_of_ColE1_high_copy_number_mutants_by_mutations_in_the_polA_gene_of_Escherichia_coli_ L2 - http://jb.asm.org/cgi/pmidlookup?view=long&pmid=8419292 DB - PRIME DP - Unbound Medicine ER -