Aedes aegypti encodes an ATPase-active RUVBL1/2 complex

RUVBL1 and RUVBL2 proteins assemble into a heterohexameric ring and are essential for DNA repair in prokaryotes and chromatin homeostasis in eukaryotes. These proteins function as potential chaperones and ATPases. While most studies on eukaryotic RUVBL1/2 proteins have focused on human and yeast orthologs, they have revealed notable differences in conformational dynamics, protein interactions, and ATPase activity between these species. By investigating orthologs in other eukaryotic organisms, conserved features of RUVBL1/2 structure and function can be determined. In this study, we analyzed the genome of Aedes aegypti, a dipteran insect and a vector of Dengue, Zika, and Chikungunya viruses, to identify putative RUVBL1/2 family members. We identified protein sequences corresponding to RUVBL1 and RUVBL2, here named as AaRUVBL1 and AaRUVBL2. Purified recombinant AaRUVBL1/2 was properly folded and formed a hetero-dodecamer in solution. The complex exhibited enzymatic ATPase activity, confirming that these proteins are bona fide AAA+ ATPases. However, mutational analysis revealed that ATPase activity requires both AaRUVBL1 and AaRUVBL2, in contrast to the human ortholog, where RUVBL1 and RUVBL2 alone are active ATPases. To characterize the structure of the AaRUVBL1/2 complex, we combined SAXS and Cryo-EM techniques. Our findings indicate that the complex adopts a dodecameric barrel-shaped complex with a maximum dimension of ∼16 nm. Single particle CryoEM analysis revealed a high degree of conformational heterogeneity, both between hexamer rings linked via the DII domains and among each hexameric ring. Overall, these findings contribute to a broader understanding of RUVBL1/2 proteins, particularly as this represents only the second structurally and functionally characterized RUVBL complex within the Animalia filum.