Linked Life Data

15686567

Source:http://linkedlifedata.com/resource/pubmed/id/15686567

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2005-2-2
pubmed:abstractText
DnaA protein binds bacterial replication origins and it initiates chromosome replication. The Caulobacter crescentus DnaA also initiates chromosome replication and the C. crescentus response regulator CtrA represses chromosome replication. CtrA proteolysis by ClpXP helps restrict chromosome replication to the dividing cell type. We report that C. crescentus DnaA protein is also selectively targeted for proteolysis but DnaA proteolysis uses a different mechanism. DnaA protein is unstable during both growth and stationary phases. During growth phase, DnaA proteolysis ensures that primarily newly made DnaA protein is present at the start of each replication period. Upon entry into stationary phase, DnaA protein is completely removed while CtrA protein is retained. Cell cycle arrest by sudden carbon or nitrogen starvation is sufficient to increase DnaA proteolysis, and relieving starvation rapidly stabilizes DnaA protein. This starvation-induced proteolysis completely removes DnaA protein even while DnaA synthesis continues. Apparently, C. crescentus relies on proteolysis to adjust DnaA in response to such rapid nutritional changes. Depleting the C. crescentus ClpP protease significantly stabilizes DnaA. However, a dominant-negative clpX allele that blocks CtrA degradation, even when combined with a clpA null allele, did not decrease DnaA degradation. We suggest that either a novel chaperone presents DnaA to ClpP or that ClpX is used with exceptional efficiency so that when ClpX activity is limiting for CtrA degradation it is not limiting for DnaA degradation. This unexpected and finely tuned proteolysis system may be an important adaptation for a developmental bacterium that is often challenged by nutrient-poor environments.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
55
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1233-45
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Regulated degradation of chromosome replication proteins DnaA and CtrA in Caulobacter crescentus.
pubmed:affiliation
Department of Microbiology and Immunology, McGill University, 3775 University Street, Room 506, Montreal, Quebec, H3A 2B4, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't