Linked Life Data

21561855

Source:http://linkedlifedata.com/resource/pubmed/id/21561855

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
2011-6-27
pubmed:abstractText
DNA ligase I (LIG1) catalyzes the ligation of single-strand breaks to complete DNA replication and repair. The energy of ATP is used to form a new phosphodiester bond in DNA via a reaction mechanism that involves three distinct chemical steps: enzyme adenylylation, adenylyl transfer to DNA, and nick sealing. We used steady state and pre-steady state kinetics to characterize the minimal mechanism for DNA ligation catalyzed by human LIG1. The ATP dependence of the reaction indicates that LIG1 requires multiple Mg(2+) ions for catalysis and that an essential Mg(2+) ion binds more tightly to ATP than to the enzyme. Further dissection of the magnesium ion dependence of individual reaction steps revealed that the affinity for Mg(2+) changes along the reaction coordinate. At saturating concentrations of ATP and Mg(2+) ions, the three chemical steps occur at similar rates, and the efficiency of ligation is high. However, under conditions of limiting Mg(2+), the nick-sealing step becomes rate-limiting, and the adenylylated DNA intermediate is prematurely released into solution. Subsequent adenylylation of enzyme prevents rebinding to the adenylylated DNA intermediate comprising an Achilles' heel of LIG1. These ligase-generated 5'-adenylylated nicks constitute persistent breaks that are a threat to genomic stability if they are not repaired. The kinetic and thermodynamic framework that we have determined for LIG1 provides a starting point for understanding the mechanism and specificity of mammalian DNA ligases.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
1083-351X
pubmed:author
pubmed:issnType
Electronic
pubmed:day
1
pubmed:volume
286
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
23054-62
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Kinetic mechanism of human DNA ligase I reveals magnesium-dependent changes in the rate-limiting step that compromise ligation efficiency.
pubmed:affiliation
Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0600, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't