Extended Data Fig. 7: Characterization of recombinant RS head complexes with point mutations causing PCD.

a, Sequence alignment of C. reinhardtii and human RSPs, showing the regions of PCD causal point-mutations (indicated with a colored box) are conserved. Residues are colored according to identity (identical – dark purple; positive – light purple). Alignment was done with T-Coffee⁴³ and the figure was prepared in Jalview⁴⁴. b-f, Amino acids in the Chlamydomonas RS head, corresponding to residues in human orthologs that when mutated cause PCD, are shown (Table 2). b, Phe170 (purple) is in the middle of a beta sheet in RSP4 (grey). When mutated to Pro it is expected to disrupt the sheet. c, A region from RSP4 colored according to residue conservation⁶⁵, highlighting Gly251 (spheres) is conserved and buried between two loops. Mutation to Glu is expected to disrupt the loop arrangement. d, MORN repeats (dashed boxes) from RSP1 colored according to residue conservation⁶⁵, indicating a conserved Gly residue in the same position for each repeat. Mutation of Gly636 to Glu is expected to disrupt the MORN repeat. e, The C’ terminal residues 262–269 in one copy of RSP9 (dark grey spheres) are positioned in a cleft created between RSP6 and RSP10 and thus in-frame deletion of the residue Arg261 (blue spheres) may affect the interaction between these three proteins. f, Tyr 244 (green) is on a beta strand in RSP9 (grey), interacting with a neighboring loop. g, Representative negative-stain EM micrographs for the RSP4 mutants, demonstrating the purified complexes are small and inhomogeneous. A micrograph of wild-type particles is shown for comparison.