Chloroplast secY is complexed to secE and involved in the translocation of the 33-kDa but not the 23-kDa subunit of the oxygen-evolving complex

Danja Schuenemann, Pinky Amin, Enno Hartmann, Neil E. Hoffman*

*Korrespondierende/r Autor/-in für diese Arbeit
67 Zitate (Scopus)

Abstract

SecY is a component of the protein-conducting channel for protein transport across the cytoplasmic membrane of prokaryotes. It is intimately associated with a second integral membrane protein, SecE, and together with SecA forms the minimal core of the preprotein translocase. A chloroplast homologue of SecY (cpSecY) has previously been identified and determined to be localized to the thylakoid membrane. In the present work, we demonstrate that a SecE homologue is localized to the thylakoid membrane, where it forms a complex with cpSecY. Digitonin solubilization of thylakoid membranes releases the SecY/E complex in a 180-kDa form, indicating that other components are present and/or the complex is a higher order oligomer of the cpSecY/E dimer. To test whether cpSecY forms the protein-conducting channel of the thylakoid membrane, translocation assays were conducted with the SecA- dependent substrate OE33 and the SecA-independent substrate OE23, in the presence and absence of antibodies raised against cpSecY. The antibodies inhibited translocation of OE33 but not OE23, indicating that cpSecY comprises the protein-conducting channel used in the SecA-dependent pathway, whereas a distinct protein conducting channel is used to translocate OE23.

OriginalspracheEnglisch
ZeitschriftJournal of Biological Chemistry
Jahrgang274
Ausgabenummer17
Seiten (von - bis)12177-12182
Seitenumfang6
ISSN0021-9258
DOIs
PublikationsstatusVeröffentlicht - 23.04.1999

Fingerprint

Untersuchen Sie die Forschungsthemen von „Chloroplast secY is complexed to secE and involved in the translocation of the 33-kDa but not the 23-kDa subunit of the oxygen-evolving complex“. Zusammen bilden sie einen einzigartigen Fingerprint.

Zitieren