Linked Life Data

9521664

Source:http://linkedlifedata.com/resource/pubmed/id/9521664

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1998-4-21
pubmed:abstractText
Reaction centers of photosystem I contain three different [4Fe-4S] clusters named FX, FA, and FB. The terminal photosystem I acceptors (FA, FB) are distributed asymmetrically along the membrane normal, with one of them (FA or FB) being reduced from FX and the other one (FB or FA) reducing soluble ferredoxin. In the present work, kinetics of electron transfer has been measured in PSI from the cyanobacterium Synechocystis sp. PCC 6803 after inactivation of FB by treatment with HgCl2. Photovoltage measurements indicate that, in the absence of FB, reduction of FA by FX is still faster than the rate of FX reduction [(210 ns)-1]. Flash-absorption measurements show that the affinity of ferredoxin for HgCl2-treated PSI is only decreased by a factor of 3-4 compared to untreated photosystem I. The first-order rate of ferredoxin reduction by FA-, within the photosystem I/ferredoxin complex, has been calculated from measurements of P700+ decay. Compared to control PSI, this rate is several orders of magnitude smaller (6 s-1 versus 10(4)-10(6) s-1). Moreover, it is smaller than the rate of recombination from FA-, resulting in inefficient ferredoxin reduction (yield of 25%). After reconstitution of FB, about half of the reconstituted photosystem I reaction centers recover fast reduction of ferredoxin with kinetics similar to that of untreated photosystem I. These results support FB as the direct partner of ferredoxin and as the more distal cluster of photosystem I with respect to the thylakoid membrane, in accordance with a linear electron-transfer pathway FX-->FA-->FB-->ferredoxin.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3429-39
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Electron transfer in photosystem I reaction centers follows a linear pathway in which iron-sulfur cluster FB is the immediate electron donor to soluble ferredoxin.
pubmed:affiliation
Département de Biologie Cellulaire et Moléculaire, CNRS, URA 2096, C.E. Saclay, Gif sur Yvette, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't