Heterotrimeric kinesin-2 motor subunit, KLP68D, localises Drosophila odour receptor coreceptor in the distal domain of the olfactory cilia

Ciliary localisation of the odour receptor coreceptor (Orco) is essential for insect olfaction. Here, we show that in the Drosophila antenna Orco enters the bipartite cilia expressed on the olfactory sensory neurons in two discrete, one-hour intervals after the adult eclosion. Genetic analyses suggest that the heterotrimeric kinesin-2 is essential for Orco transfer from the base into the cilium. Using in vitro pulldown assay, we show that Orco binds to the C-terminal tail domain of KLP68D, the {beta}-subunit of kinesin-2. Reduced Orco enrichment decreases electrophysiological response to odours and loss of olfactory behaviour. Finally, we show that kinesin-2 function is necessary to compact Orco to an approximately four-micron stretch at the distal portion of the ciliary outer-segment bearing singlet microtubule filaments. Altogether, these results highlight an independent, tissue-specific regulation of Orco entry at specific developmental stages and its localisation to a ciliary subdomain by kinesin-2. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/395905v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@177d376org.highwire.dtl.DTLVardef@1dc14d6org.highwire.dtl.DTLVardef@1dc2d21org.highwire.dtl.DTLVardef@16e90c_HPS_FORMAT_FIGEXP M_FIG C_FIG Author SummaryJana, Jain, Dutta et al., show that the odour receptor coreceptor only enters the cilia expressed on olfactory sensory neurons at specified developmental stages requiring heterotrimeric kinesin-2. The motor also helps to localise the coreceptor in a compact, environment-exposed domain at the ciliary outer-segment. HighlightsO_LIOdorant receptor coreceptor (Orco) selectively enters the olfactory cilia. C_LIO_LIOrco localises in a specific domain at the distal segment of the olfactory cilium. C_LIO_LIOrco/ORx binds to the C-terminal tail domain of the kinesin-2{beta} motor subunit. C_LIO_LIOrco entry across the transition zone and its positioning require Kinesin-2. C_LI