Abstract：
:Insertion and deletion mutagenesis within the gene topA of Escherichia coli encoding DNA topoisomerase I was carried out to test the existence of subdomains in the enzyme and the relationship between the slow-growth topA- phenotype and the known DNA relaxation activity of the enzyme. All mutants that show no detectable DNA relaxation activity in cell extracts fail to complement the temperature-sensitive growth defect of strain AS17 topAam harboring a plasmid-borne temperature-sensitive suppressor tRNA. All mutants that show partial or full levels of DNA relaxation activity in cell extracts (relative to activity in extracts of wild-type cells) can complement this defect. The carboxyl-proximal 25% of the enzyme appears to be in a domain that is dispensable both in terms of the catalytic function of the enzyme and its biological role. Analysis of the mutant enzyme also indicates that the formation of the covalent topoisomerase-DNA complex is correlated with the DNA relaxation activity, which supports the notion that the covalent complex is an obligatory intermediate in the catalysis of DNA topoisomerization.
journal_name
J Mol Bioljournal_title
Journal of molecular biologyauthors
Zumstein L,Wang JCdoi
10.1016/0022-2836(86)90130-0subject
Has Abstractpub_date
1986-10-05 00:00:00pages
333-40issue
3eissn
0022-2836issn
1089-8638pii
0022-2836(86)90130-0journal_volume
191pub_type
杂志文章abstract：:The two-component signaling protein CtrA activates or represses the expression of one-quarter of the cell-cycle-regulated genes in Caulobacter crescentus, integrating DNA replication, morphogenesis, and cell division. The activity of this essential protein is controlled by a positive transcriptional feedback loop, cel...
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doi：10.1006/jmbi.1996.0749
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doi：10.1006/jmbi.1994.1258
更新日期：1994-04-15 00:00:00
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doi：10.1016/0022-2836(89)90337-9
更新日期：1989-11-20 00:00:00
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journal_title：Journal of molecular biology
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doi：10.1006/jmbi.1996.0826
更新日期：1997-03-21 00:00:00
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