Protein subcellular relocalization and function of duplicated flagellar calcium binding protein genes in honey bee trypanosomatid parasite

Abstract

AbstractThe honey bee trypanosomatid parasite,Lotmaria passim, contains two genes that encode the flagellar calcium binding protein (FCaBP) through tandem duplication in its genome. FCaBPs localize in the flagellum and cell body ofL. passimthrough specific N-terminal sorting sequences. This finding suggests that this is an example of protein subcellular relocalization resulting from gene duplication, altering the intracellular localization of FCaBP. However, this phenomenon may not have occurred inLeishmania, as one or both of the duplicated genes have become pseudogenes. Multiple copies of theFCaBPgene are present in severalTrypanosomaspecies andLeptomonas pyrrhocoris, indicating rapid evolution of this gene in trypanosomatid parasites. The N-terminal flagellar sorting sequence ofL. passimFCaBP1 interacts with the BBSome complex, while those ofTrypanosoma bruceiandLeishmania donovaniFCaBPs do not direct GFP to the flagellum inL. passim. These results suggest that the N-terminal flagellar sorting sequence of FCaBP1 has co-evolved with the BBSome complex in each trypanosomatid species. Deletion of the twoFCaBPgenes inL. passimaffected growth and impaired flagellar morphogenesis and motility, but it did not impact host infection. Therefore,FCaBPrepresents a duplicated gene with a rapid evolutionary history that is essential for flagellar structure and function in a trypanosomatid parasite.