Linked Life Data

12882981

Source:http://linkedlifedata.com/resource/pubmed/id/12882981

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
41
pubmed:dateCreated
2003-10-6
pubmed:abstractText
The Crabtree-negative yeast Kluyveromyces lactis is capable of adjusting its glycolytic flux to the requirements of respiration by tightly regulating glucose uptake. RAG5 encoding the only glucose and fructose phosphorylating enzyme present in K. lactis is required for the up-regulation of glucose transport and also for glucose repression. To understand the significance of the molecular identity and specific function(s) of the corresponding kinase to glucose signaling, RAG5 was overexpressed and its gene product KlHxk1 (Rag5p) isolated and characterized. Stopped-flow kinetics and sedimentation analysis indicated a monomer-homodimer equilibrium of KlHxk1 in a condition of catalysis, i.e. in the presence of substrates and products. The kinetic constants of ATP-dependent glucose phosphorylation identified a 53-kDa monomer as the high affinity/high activity form of the novel enzyme for both glycolytic substrates suggesting a control of glucose phosphorylation at the level of dimer formation and dissociation. In contrast to the highly homologous hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2), KlHxk1 was not inhibited by free ATP in a physiological range of nucleotide concentration. Mass spectrometric sequencing of tryptic peptides of KlHxk1 identified unmodified serine at amino acid position 156. The corresponding amino acid in ScHxk2 is serine 157, which represents the autophosphorylation-inactivation site. KlHxk1 did not display, however, the typical pattern of inactivation under the respective in vitro conditions and maintained a high residual glucose phosphorylating activity. The biophysical and functional data are discussed with respect to a possible regulatory role of KlHxk1 in glucose metabolism and signaling in K. lactis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
278
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
39280-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
The unique hexokinase of Kluyveromyces lactis. Molecular and functional characterization and evaluation of a role in glucose signaling.
pubmed:affiliation
Technische Universität Dresden, Medizinische Fakultät Carl Gustav Carus, Institut für Physiologische Chemie, Fetscherstr. 74, D-01307 Dresden, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't