Linked Life Data

8125105

Source:http://linkedlifedata.com/resource/pubmed/id/8125105

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1994-4-14
pubmed:abstractText
Aerobically grown Escherichia coli GM48 harboring plasmid pKScitS that codes for the sodium-dependent citrate carrier from Klebsiella pneumoniae (CitS) allows initial-rate measurements of citrate uptake in whole cells. The cation stoichiometry and selectivity of CitS was studied using this experimental system. The relationship between the initial rate of uptake of citrate and the Na+ concentration was sigmoidal at pH values between 5 and 7 suggesting a Na+ stoichiometry higher than 1. Rates of uptake increased quadratically in a range of non-saturating Na+ concentrations showing that two Na+ are translocated/catalytic cycle. Symport of Na+ is absolutely required in the range pH 5-7 because no uptake could be detected in the absence of Na+. Protons cannot replace Na+ in the translocation step but the decrease in apparent affinity for Na+ towards lower pH suggests that protons can compete with Na+ for the cation-binding sites. Li+ can replace Na+ in the symport reaction but it takes about a 200-fold higher concentration of Li+ over Na+ to achieve the same rate of uptake, showing that the affinity of CitS for Li+ is much lower than for Na+. Though high Li+ concentrations have an inhibitory effect on citrate uptake, the data suggest that the Li+ stoichiometry is also 2.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
220
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
469-75
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Transport of citrate catalyzed by the sodium-dependent citrate carrier of Klebsiella pneumoniae is obligatorily coupled to the transport of two sodium ions.
pubmed:affiliation
Department of Microbiology, University of Groningen, Haren, The Netherlands.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't