Linked Life Data

8604132

Source:http://linkedlifedata.com/resource/pubmed/id/8604132

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1996-5-16
pubmed:abstractText
Escherichia coli DNA gyrase, as well as a free form of its A subunit (GyrA), exists in an inactivated form in cells that overproduce the F plasmid protein LetD (CcdB). We found that the inactivated DNA gyrase and GyrA protein can be rejuvenated in vitro by another F plasmid protein, LetA (CcdA). Using this rejuvenation as an assay, we purified the inactivated GyrA protein to near homogeneity and found it to be complexed with the LetD protein. The complex has a molecular mass of 230 kDa and was suggested to be a complex of two molecules each of GyrA and LetD proteins. The GyrA-LetD complex, in the presence of purified GyrB protein, does not cause DNA cleavage. Therefore, the LetD protein in the GyrA-LetD complex inhibits the gyrase action by a mechanism different from one that involves trapping a covalently linked gyrase-DNA complex. In as much as a free form of the LetD protein has been shown to induce DNA cleavage by gyrase, the LetD protein seems to have two distinct modes of action on DNA gyrase. Rejuvenation of the inactivated GyrA protein by the LetA protein was achieved in vitro, and mechanisms governing this process were examined using the purified proteins. The rejuvenated GyrA protein sediments through sucrose gradients as a single protein species of 190 kDa and is indistinguishable from a free form of GyrA protein. In the same sedimentation experiment, the LetD protein was seen to be complexed with the added LetA protein. Thus, the LetA protein apparently rejuvenates the GyrA protein by removing the bound LetD protein from the inactivated form, followed by formation of a LetA-LetD complex.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
256
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
473-82
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Partner switching mechanisms in inactivation and rejuvenation of Escherichia coli DNA gyrase by F plasmid proteins LetD (CcdB) and LetA (CcdA).
pubmed:affiliation
Faculty of Pharmaceutical Sciences, Kyushu Univeristy, Fukuoka, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't