NDUFAF3 is involved in the assembly of the Q/P module of respiratory complex I in the green microalga Chlamydomonas reinhardtii

ABSTRACT: The mitochondrial NADH:ubiquinone oxidoreductase, or complex I, is composed of a hydrophobic arm comprising the P module and a hydrophilic arm comprising the N and Q modules. The assembly of complex I is well characterized in humans and catalyzed by a series of assembly factors that join the Q, P, and N modules sequentially. The complex I of protists and plants contains additional ancestral features, like the ferredoxin bridge that connects the matrix and the membrane arms and the carbonic anhydrase domain, which raises the question of their assembly. In this work, a strain where the assembly factor NDUFAF3 has been tagged with a 3xFLAG at the C-terminal extremity has been investigated in the green microalga Chlamydomonas reinhardtii. Like its human homolog, NDUFAF3 interacts strongly with the classical subunits of the Q and P modules, but also with the carbonic anhydrase domain and C1-FDX, one of the subunits of the ferredoxin bridge. The predicted structural positioning of NDUFAF3 within the Q module suggests a role in the formation of the ferredoxin bridge. In contrast, subunits of the N module are only loosely associated with NDUFAF3. We further demonstrate that the N module is attached at a later stage of assembly, suggesting that Chlamydomonas complex I assembles in a human-like pathway. This contrasts with the situation in Angiosperms where the N and the Q modules are attached together before anchoring to the P module. Altogether, these results highlight a conserved and ancestral role of NDUFAF3 in complex I manufacture.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Chlamydomonas Reinhardtii

SUBMITTER: Johana Chicher  

LAB HEAD: Thalia Salinas-Giegé

PROVIDER: PXD048077 | Pride | 2025-07-15

REPOSITORIES: Pride