Characterization of the alpha and beta-subunits of the F0F1-ATPase from the alga Polytomella spp., a colorless relative of Chlamydomonas reinhardtii

被引:26
作者
Atteia, A [1 ]
Dreyfus, G [1 ]
GonzalezHalphen, D [1 ]
机构
[1] NATL AUTONOMOUS UNIV MEXICO,INST FISIOL CELULAR,DEPT BIOENERGET,MEXICO CITY 04510,DF,MEXICO
来源
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS | 1997年 / 1320卷 / 03期
关键词
colorless alga; mitochondrion; ATPase; F0F1; (Polytomella); (Chlamydomonas reinhardtii);
D O I
10.1016/S0005-2728(97)00031-5
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The isolation and partial characterization of the oligomycin-sensitive F0F1-ATP synthase/ATPase from the colorless alga Polytomella spp. is described. Purification was performed by solubilization with dodecyl-beta-D-maltoside followed by Sepharose Hexyl ammonium chromatography, a matrix that interacts with the F-1 sector of mitochondrial ATPases. The alpha-subunit, which migrates on SDS-polyacrylamide gels with an apparent molecular mass of 55 kDa, was identified by the N-terminal sequencing of 47 residues. This subunit exhibited a short extension at its N-terminus highly similar to the one described for the unicellular alga Chlamydomonas reinhardtii (Nurani, G. and Franzen L.-G. (1996) Plant Mel. Biol. 31, 1105-1116). In whole mitochondria, the alpha-subunit was susceptible to limited proteolytic digestion induced by heat. An endogenous protease removed the first 22 residues of the mature alpha-subunit. Subunit beta was also identified by N-terminal sequencing of 31 residues. This subunit of 63 kDa exhibited a higher apparent molecular mass than alpha, as judged by its mobility on denaturing polyacrylamide gel electrophoresis. This beta-subunit is 7-8 kDa larger than the beta-subunits of other mitochondrial ATPases. It is suggested that the beta-subunit from Polytomella spp. may have a C-terminal extension similar to that described for the green alga C. reinhardtii (Franzen, L.-G. and Falk, G. (1992) Plant Mol. Biol. 19, 771-780). In addition, it was found that the C-terminal extension of the beta-subunit of C. reinhardtii showed homology with the endogenous ATPase inhibitors from various sources and with the epsilon-subunit from the F0F1-ATP synthase from Escherichia coli, which is considered to be a functional homolog of the inhibitor proteins. The data reported here provide the first biochemical evidence for a close relationship between the colorless alga Polytomella spp. and its photosynthetic counterpart C. reinhardtii. It is also suggested that the C-terminal extensions of the beta-subunits of the ATP synthases from these algae, may play a regulatory role in these enzymes.
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页码:275 / 284
页数:10
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