Novel interactors of the Drosophila Survival Motor Neuron (SMN) Complex suggest its full conservation

The Spinal Muscular Atrophy disease protein Survival Motor Neuron (SMN) operates as part of a multiprotein complex whose components also include Gemins 2-8 and Unrip. The fruit fly Drosophila melanogaster is thought to have a slightly smaller SMN complex comprised of SMN, Gemin2/3/5 and, possibly, Unrip. Based upon in vivo interaction methods, we have identified novel interacting partners of the Drosophila SMN complex with homologies to Gemin4/6/7/8. The Gemin4 and Gemin8 orthologues are required for neuromuscular function and survival. The Gemin6/7/Unrip module can be recruited via the SMN-associated Gemin8, hence mirroring the human SMN complex architecture. Our findings lead us to propose that an elaborate SMN complex that is typical in metazoans is also present in Drosophila.