Characterization of the PetM subunit of the b₆f complex from higher plants

authored by

Marion Kügler, Volker Kruft, Udo Schmitz, Hans-Peter Braun

Abstract

The chloroplast cytochrome b₆f complex comprises seven subunits, three of which - designated the PetG, PetL and PetM proteins - are very small. To determine structural data on the PetM protein from higher plants the spinach b₆f complex was isolated by a novel isolation procedure based on blue native polyacrylamide gel electrophoresis (BN-PAGE). Starting with only 30 mg of chloroplast protein the enzyme complex is obtained in very pure form as demonstrated by analysis with Tricine-SDS/PAGE. The primary structure of the PetM subunit was investigated by direct amino acid sequencing and by sequencing of a corresponding cDNA clone from Arabidopsis thaliana. Arabidopsis PetM comprises 40 amino acids and is synthesized with a N-terminal extension of 56 amino acids that resembles stroma-targeting peptides. Hence, the PetM protein is assumed to be nuclear encoded and posttranslationally imported into chloroplasts. Arabidopsis PetM exhibits 58 % sequence identity with PetM from Chlamydomonas. Furthermore, Arabidopsis PetM resembles the deduced amino acid sequences of small organelle-encoded open reading frames of the red alga Porphyra purpurea, the diatom Odontella sinensis, the green alga Cyanophora paradoxa and the cyanobacterium Synechocystis. The primary structure of PetM does not show any significant sequence similarity to the sequences of one of the small subunits of the mitochondrial bc₁ complex. The overall subunit compositions of chloroplast b₆f complexes and mitochondrial bc₁ complexes are compared and discussed.

Organisation(s)

Section Plant Molecular Biology and Plant Proteomics

External Organisation(s)

Applied Biosystems GmbH

Type

Article

Journal

Journal of Plant Physiology

Volume

153

Pages

581-586

No. of pages

6

ISSN

0176-1617

Publication date

1998

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Physiology, Agronomy and Crop Science, Plant Science

Electronic version(s)

https://doi.org/10.1016/S0176-1617(98)80207-1 (Access: Unknown)