Linked Life Data

15498760

Source:http://linkedlifedata.com/resource/pubmed/id/15498760

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2005-1-17
pubmed:abstractText
Previous examination of the accessibility of a panel of single-Cys mutants in transmembrane domain III (TMDIII) of the yeast mitochondrial citrate transport protein to hydrophilic, cysteine-specific methanethiosulfonate reagents, enabled identification of the water-accessible surface of this domain and suggested its potential participation in the formation of a portion of the substrate translocation pathway. To evaluate this idea, we conducted a detailed characterization of the functional properties of 20 TMDIII single-Cys substitution mutants. Kinetic studies indicate that the A118C, S123C, and K134C mutants displayed a 3- to 7-fold increase in K(m). Moreover, the A118C mutation caused a doubling of the V(max) value, whereas the S123C, E131C, and K134C mutations caused V(max) to dramatically decrease, resulting in a reduction of the catalytic efficiencies of these three mutants by >97%. Examination of the ability of citrate to protect against the inhibition mediated by sodium (2-sulfonatoethyl)methanethiosulfonate (MTSES) indicated that citrate conferred significant protection of cysteines substituted at eight water-accessible locations (i.e. Gly-115, Leu-116, Gly-117, Leu-121, Ser-123, Val-127, Glu-131, and Thr-135), but not at other sites. Importantly, similar levels of protection were observed at both 4 degrees C and 20 degrees C. The temperature independence of the protection indicates that substrate binding and/or occupancy of the transport pathway sterically blocks the access of MTSES to these sites, thereby providing direct protection, without involvement of a major protein conformational change. The significance of these extensive functional investigations is discussed in terms of the three-dimensional CTP homology model that we previously developed and a new model of the dimer interface.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2331-40
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
The yeast mitochondrial citrate transport protein: characterization of transmembrane domain III residue involvement in substrate translocation.
pubmed:affiliation
Department of Biochemistry & Molecular Biology, Rosalind Franklin University of Medicine and Science/The Chicago Medical School, North Chicago, Illinois 60064, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.