Ancestral centriole and flagella proteins identified by analysis ofNaegleriadifferentiation

Naegleria gruberi is a single-celled eukaryote best known for its remarkable ability to form an entire microtubule cytoskeleton de novo during its metamorphosis from an amoeba into a flagellate, including basal bodies (equivalent to centrioles), flagella and a cytoplasmic microtubule array. Our publicly available full-genome transcriptional analysis, performed at 20-minute intervals throughout Naegleria differentiation, reveals vast transcriptional changes, including the differential expression of genes involved in metabolism, signaling and the stress response. Cluster analysis of the transcriptional profiles of predicted cytoskeletal genes reveals a set of 55 genes enriched in centriole components (induced early) and a set of 82 genes enriched in flagella proteins (induced late). The early set includes genes encoding nearly every known conserved centriole component, as well as eight previously uncharacterized, highly conserved genes. The human orthologs of at least five genes localize to the centrosomes of human cells, one of which (here named Friggin) localizes specifically to mother centrioles.