Purification and characterization of the preprotein translocase of the outer mitochondrial membrane from Arabidopsis. Identification of multiple forms of TOM20

verfasst von

Wolf Werhahn, A. Niemeyer, Lothar Jänsch, Volker Kruft, Udo Schmitz, Hans-Peter Braun

Abstract

The translocase of the outer mitochondrial membrane (TOM) complex is a preprotein translocase that mediates transport of nuclear-encoded mitochondrial proteins across the outer mitochondrial membrane. Here we report the purification of this protein complex from Arabidopsis. On blue-native gels the Arabidopsis TOM complex runs at 230 kD and can be dissected into subunits of 34, 23, 21, 8, 7, and 6 kD. The identity of four subunits could be determined by immunoblotting and/or direct protein sequencing. The 21- and the 23-kD subunits exhibit significant sequence homology to the TOM20 preprotein receptor from other organisms. Analysis by two-dimensional isoelectric focusing/Tricine sodium dodecyl sulfide-polyacrylamide gel electrophoresis revealed the presence of further forms for Arabidopsis TOM20. All TOM20 proteins comprise a large cytoplasmically exposed hydrophilic domain, which is degraded upon trypsination of intact mitochondria. Clones encoding four different forms of Arabidopsis TOM20 were identified and sequenced. The deduced amino acid sequences are rather conserved in the N-terminal half and in the very C-terminal part, but include a highly variable glycine-rich region close to the C terminus. Implications on the function of plant TOM complexes are discussed. Based on peptide and nucleic acid sequence data, the primary structure for Arabidopsis TOM40 is presented.

Organisationseinheit(en)

Abteilung Pflanzenmolekularbiologie und Pflanzenproteomik

Typ

Artikel

Journal

Plant Physiology

Band

125

Seiten

943-954

Anzahl der Seiten

12

ISSN

0032-0889

Publikationsdatum

06.03.2001

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Physiologie, Genetik, Pflanzenkunde

Elektronische Version(en)

https://doi.org/10.1104/pp.125.2.943 (Zugang: Offen)