Atomic structures of respiratory complex III₂, complex IV and supercomplex III₂-IV from vascular plants

Abstract

Mitochondrial complex III (CIII2) and complex IV (CIV), which can associate into a higher-order supercomplex (SC III2+IV), play key roles in respiration. However, structures of these plant complexes remain unknown. We present atomic models of CIII2, CIV and SC III2+IV from Vigna radiata determined by single-particle cryoEM. The structures reveal plant-specific differences in the MPP domain of CIII2 and define the subunit composition of CIV. Conformational heterogeneity analysis of CIII2 revealed long-range, coordinated movements across the complex, as well as the motion of CIII2’s iron-sulfur head domain. The CIV structure suggests that, in plants, proton translocation does not occur via the H-channel. The supercomplex interface differs significantly from that in yeast and bacteria in its interacting subunits, angle of approach and limited interactions in the mitochondrial matrix. These structures challenge long-standing assumptions about the plant complexes, generate new mechanistic hypotheses and allow for the generation of more selective agricultural inhibitors.

Structural insights into the assembly and the function of the plant oxidative phosphorylation system

“…The recent structure of CIV from mung bean provided a complementary approach to determine the subunit composition of this elusive complex (Maldonado et al ., 2021). The structural data established that plant CIV contains 10 subunits, as opposed to 12 in yeast (Hartley et al ., 2019; Rathore et al ., 2019) and 13 in mammals (Yano et al ., 2016).…”

“…Structures of CI (Soufari et al ., 2020; Klusch et al ., 2021), a CI fragment (Maldonado et al ., 2020), and an assembly intermediate of CI called CI* (Soufari et al ., 2020) were obtained from mung bean, cauliflower, Arabidopsis , and Polytomella . Additionally, structures of complex III 2 (CIII 2 ), complex IV (CIV), and SC III 2 + IV (Maldonado et al ., 2021) were obtained from mung bean. These structures revealed several plant‐specific features of the complexes and generated new mechanistic hypotheses on plant‐specific aspects of respiration.…”

Organellar transcripts dominate the cellular mRNA pool across plants of varying ploidy levels

“…Structure of cytochrome c oxidase from the angiosperm Vigna radiata (70). Mitochondrial-encoded subunits Cox1, Cox2, and Cox3 are shown in shades of orange to red.…”

Structural insight on the mechanism of an electron-bifurcating [FeFe] hydrogenase

“…Despite extensive attempts, we were unable to find a class with both bridges in the closed conformation. The observation that both bridges cannot close simultaneously suggests that these behave as reciprocating elements similarly to the Rieske domain in the bifurcating bc1 complex (28). To further explore the particles without a bridge a further classification was used (Fig.…”