Linked Life Data

7592702

Source:http://linkedlifedata.com/resource/pubmed/id/7592702

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
43
pubmed:dateCreated
1995-12-14
pubmed:abstractText
Citrate uptake in Leuconostoc mesenteroides subsp. mesenteroides 19D is catalyzed by a secondary citrate carrier (CitP). The kinetics and mechanism of CitP were investigated in membrane vesicles of L. mesenteroides. The transporter is induced by the presence of citrate in the medium and transports both citrate and malate. In spite of sequence homology to the Na(+)-dependent citrate carrier of Klebsiella pneumoniae, CitP is not Na(+)-dependent, nor is CitP Mg(2+)-dependent. The pH gradient (delta pH) is a driving force for citrate and malate uptake into the membrane vesicles, whereas the membrane potential (delta psi) counteracts transport. An inverted membrane potential (inside positive) generated by thiocyanide diffusion can drive citrate and malate uptake in membrane vesicles. Analysis of the forces involved showed that a single unit of negative charge is translocated during transport. Kinetic analysis of citrate counterflow at different pH values indicated that CitP transports the dianionic form of citrate (Hcit2-) with an affinity constant of approximately 20 microns. It is concluded that CitP catalyzes Hcit2-/H+ symport. Translocation of negative charge into the cell during citrate metabolism results in the generation of a membrane potential that contributes to the protonmotive force across the cytoplasmic membrane, i.e. citrate metabolism in L. mesenteroides generates metabolic energy. Efficient exchange of citrate and D-lactate, a product of citrate/carbohydrate co-metabolism, is observed, suggesting that under physiological conditions, CitP may function as an electrogenic precursor/product exchanger rather than a symporter. The mechanism and energetic consequences of citrate uptake are similar to malate uptake in lactic acid bacteria.
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
27
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
25370-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Membrane potential-generating transport of citrate and malate catalyzed by CitP of Leuconostoc mesenteroides.
pubmed:affiliation
Department of Microbiology, Groningen Biotechnology and Biomolecular Sciences Institute, University of Groningen, Haren, The Netherlands.
pubmed:publicationType
Journal Article, Comparative Study