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Titolo:
Insertion of PsaK into the thylakoid membrane in a "horseshoe" conformation occurs in the absence of signal recognition particle, nucleoside triphosphates, or functional Albino3
Autore:
Mant, A; Woolhead, CA; Moore, M; Henry, R; Robinson, C;
Indirizzi:
Univ Warwick, Dept Biol Sci, Coventry CV4 7AL, W Midlands, England Univ Warwick Coventry W Midlands England CV4 7AL 7AL, W Midlands, England Univ Warwick, Dept Chem, Coventry CV4 7AL, W Midlands, England Univ Warwick Coventry W Midlands England CV4 7AL 7AL, W Midlands, England Univ Arkansas, Dept Biol Sci, Fayetteville, AR 72701 USA Univ Arkansas Fayetteville AR USA 72701 l Sci, Fayetteville, AR 72701 USA
Titolo Testata:
JOURNAL OF BIOLOGICAL CHEMISTRY
fascicolo: 39, volume: 276, anno: 2001,
pagine: 36200 - 36206
SICI:
0021-9258(20010928)276:39<36200:IOPITT>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIGHT-HARVESTING COMPLEX; PSI-K SUBUNIT; ESCHERICHIA-COLI; PROTEIN-TRANSPORT; POSTTRANSLATIONAL INTEGRATION; INDEPENDENT INSERTION; INNER MEMBRANE; PHOTOSYSTEM-I; SEC; HOMOLOG;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Robinson, C Univ Warwick, Dept Biol Sci, Coventry CV4 7AL, W Midlands, England Univ Warwick Coventry W Midlands England CV4 7AL nds, England
Citazione:
A. Mant et al., "Insertion of PsaK into the thylakoid membrane in a "horseshoe" conformation occurs in the absence of signal recognition particle, nucleoside triphosphates, or functional Albino3", J BIOL CHEM, 276(39), 2001, pp. 36200-36206

Abstract

The photosystem I subunit PsaK spans the thylakoid membrane twice, with the N and C termini both located in the lumen. The insertion mechanism of a thylakoid membrane protein adopting this type of topology has not been studied before, and we have used in vitro assays to determine the requirements for PsaK insertion into thylakoids. PsaK inserts with high efficiency and weshow that one transmembrane span (the C-terminal region) can insert independently of the other, indicating that a "hairpin"-type mechanism is not essential. Insertion of PsaK does not require stromal extract, indicating thatsignal recognition particle (SRP) is not involved. Removal of nucleoside triphosphates inhibits insertion only slightly, both in the presence and absence of stroma, suggesting a mild stimulatory effect of a factor in the translation system and again ruling out an involvement of SRP or its partner protein, FtsY. We, furthermore, rind no evidence for the involvement of known membrane-bound translocation apparatus; proteolysis of thylakoids destroys the See and Tat translocons but does not block PsaK insertion, and antibodies against the Oxa1/YidC homolog, Alb3, block the SRP-dependent insertionof Lhcb1 but again have no effect on PsaK insertion. Because YidC is required for the efficient insertion of every membrane protein tested in Escherichia coli (whether SRP-dependent or -independent), PsaK is the first protein identified as being independent of YidC/Alb3-type factors in either thylakoids or bacteria. The data raise the possibility of a wholly spontaneous insertion pathway.

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Documento generato il 09/04/20 alle ore 19:10:21