Subunit–subunit interactions and overall topology of the dimeric mitochondrial ATP synthase of Polytomella sp.

Abstract

Mitochondrial F1F0-ATP synthase of chlorophycean algae is a dimeric complex of 1600 kDa constituted by 17 different subunits with varying stoichiometries, 8 of them conserved in all eukaryotes and 9 that seem to be unique to the algal lineage (subunits ASA1-9). Two different models proposing the topological assemblage of the nine ASA subunits in the ATP synthase of the colorless alga Polytomella sp. have been put forward. Here, we readdressed the overall topology of the enzyme with different experimental approaches: detection of close vicinities between subunits based on cross-linking experiments and dissociation of the enzyme into subcomplexes, inference of subunit stoichiometry based on cysteine residue labelling, and general three-dimensional structural features of the complex as obtained from small-angle X-ray scattering and electron microscopy image reconstruction. Based on the available data, we refine the topological arrangement of the subunits that constitute the mitochondrial ATP synthase of Polytomella sp.

Structure of the yeast F 1 F o -ATP synthase dimer and its role in shaping the mitochondrial cristae

“…The Polytomella dimer has been examined by single-particle analysis (35) and subtomogram averaging (36). The two reported structures differ in terms of dimer angle (50°or 70°) and the proposed interaction of peripheral stalks at the dimer interface.…”

Atypical Cristae Morphology of Human Syncytiotrophoblast Mitochondria

“…(15,16), and Chlamydomonas reinhardtii (17,18). The F 0 F 1 -ATP synthase dimer (V 2 ) seems to be closely related with the mitochondrial architecture.…”

Respiratory-deficient mutants of the unicellular green alga Chlamydomonas: A review

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 16 [17], (c) [68], (d) [69], (e) [70], (f) [71], (g) [72], (h) [73], (i) [74], (j) [75], (k) [76], (l) [77], (m) [22], (n) [29], (o) [78], (p) [58], (q) [79], (r)[34] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 17 ((a) [48], (b) [45], (c) [47], (d) [43], (e) [44], (f) [39], (g) …”

“…In dark-grey is represented the complex V with its F 1 and F O domains linked by the central stalk. In light-grey are represented the peripheral stalk and the dimerization module constituted of algal-specific subunits (ASA subunits) [29]. The respiratory mutants can be divided into two phenotypic classes when cultivated under heterotrophic conditions.…”

“…Like other chlorophycean algae, C. reinhardtii exhibits a highly stable dimeric mitochondrial F 1 F O -ATP synthase with an apparent molecular mass of 1600 kDa [25]. This dimeric enzyme complex has a unique architecture with a robust peripheral stalk [26][27][28][29] (Fig. 1B).…”