TY - JOUR

T1 - Characterization of the PetM subunit of the b6f complex from higher plants

AU - Kügler, Marion

AU - Kruft, Volker

AU - Schmitz, Udo

AU - Braun, Hans-Peter

PY - 1998

Y1 - 1998

N2 - 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.

AB - 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.

KW - Arabidopsis thaliana

KW - Chloroplasts

KW - Cytochrome bf complex

KW - Photosynthesis

KW - Protein targeting

KW - Spinacea oleracea

UR - http://www.scopus.com/inward/record.url?scp=0032405767&partnerID=8YFLogxK

U2 - 10.1016/S0176-1617(98)80207-1

DO - 10.1016/S0176-1617(98)80207-1

M3 - Article

AN - SCOPUS:0032405767

VL - 153

SP - 581

EP - 586

JO - Journal of Plant Physiology

JF - Journal of Plant Physiology

SN - 0176-1617

IS - 5-6

ER -