Linked Life Data

1577811

Source:http://linkedlifedata.com/resource/pubmed/id/1577811

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
1992-6-9
pubmed:abstractText
Exploitation of differences in the substrate specificity of the type I and type II thymidine kinases (EC 2.7.1.21, TK) expressed by the Herpesviridae and Poxviridae (and human cells), respectively, has lead to the development of effective antiherpetic drugs such as acyclovir and gancyclovir. Analysis of type I TK protein sequences reveals a consensus sequence which corresponds to domain IV of type II TK proteins such as that encoded by vaccinia virus (VV). The type I descriptor (Xpho - + + Xpho) differs at the second position from the type II consensus sequence (Xpho Xphi + + Xpho) by having an aspartic acid residue (D) substituted for a glutamine (Q). To test the hypothesis that this substitution may be responsible for the observed differences in substrate specificity of these enzymes and as a approach to identify the nucleoside binding site of the type II VV TK, site-directed mutagenesis was employed to alter glutamine 114 (Q114) within domain IV of VV TK to a histidine (Q114H) or an aspartic acid (Q114D). All of the mutant enzymes retained full enzymatic activity as compared to wild-type VV TK when thymidine or bromodeoxyuridine were used as substrates. However, unlike the wild-type herpes simplex (type 1) TK enzyme, neither wild-type nor domain IV VV TK mutants were able to phosphorylate acyclovir or cytidine substrates. Surprisingly, the domain IV VVTK mutants displayed a dramatic loss of feedback inhibition by dTTP. Mutations of the Q114 position also lead to a difference in ATP binding as demonstrated by an altered elution pattern of Q114H and Q114D from an ATP-agarose affinity column with dTTP. Taken together, these results suggest that domain IV of VV TK is not involved directly in substrate discrimination but instead participates in feedback inhibition by dTTP.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9743-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:1577811-Acyclovir, pubmed-meshheading:1577811-Amino Acid Sequence, pubmed-meshheading:1577811-Bromodeoxyuridine, pubmed-meshheading:1577811-Chromatography, Affinity, pubmed-meshheading:1577811-Codon, pubmed-meshheading:1577811-Cytidine, pubmed-meshheading:1577811-Feedback, pubmed-meshheading:1577811-Genetic Vectors, pubmed-meshheading:1577811-Humans, pubmed-meshheading:1577811-Kinetics, pubmed-meshheading:1577811-Methionine, pubmed-meshheading:1577811-Molecular Sequence Data, pubmed-meshheading:1577811-Mutagenesis, Site-Directed, pubmed-meshheading:1577811-Recombinant Proteins, pubmed-meshheading:1577811-Substrate Specificity, pubmed-meshheading:1577811-Thymidine, pubmed-meshheading:1577811-Thymidine Kinase, pubmed-meshheading:1577811-Transcription, Genetic, pubmed-meshheading:1577811-Vaccinia virus
pubmed:year
1992
pubmed:articleTitle
A single amino acid substitution abolishes feedback inhibition of vaccinia virus thymidine kinase.
pubmed:affiliation
Department of Microbiology, Oregon State University, Corvallis 97331-3804.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't