The RAB family GTPase Rab1A from Plasmodium falciparum defines a unique paralog shared by chromalveolates and rhizaria.
The RAB GTPases, which are involved in regulation of endomembrane trafficking, exhibit a complex but incompletely understood evolutionary history. We elucidated the evolution of the RAB1 subfamily ancestrally implicated in the endoplasmic reticulum-to-Golgi traffic. We found that RAB1 paralogs have been generated over the course of eukaryotic evolution, with some duplications coinciding with the advent of major eukaryotic lineages (e.g. Metazoa, haptophytes). We also identified a unique, derived RAB1 paralog, orthologous to the Plasmodium Rab1A, that occurs in stramenopiles, alveolates, and Rhizaria, represented by the chlorarachniophyte Gymnochlora stellata. This finding is consistent with the recently documented existence of a major eukaryotic clade ("SAR") comprising these three lineages. We further found a Rab1A-like protein in the cryptophyte Guillardia theta, but it exhibits unusual features among RAB proteins: absence of a C-terminal prenylation motif and an N-terminal extension with two MSP domains; and its phylogenetic relationships could not be established convincingly due to its divergent nature. Our results nevertheless point to a unique membrane trafficking pathway shared by at least some lineages of chromalveolates and Rhizaria, an insight that has implications towards interpreting the early evolution of eukaryotes and the endomembrane system.
Elias
Marek
M
Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic. melias@natur.cuni.cz
Patron
Nicola J
NJ
Keeling
Patrick J
PJ
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D044785:Cryptophyta / Q000201:enzymology* / Q000235:genetics; D048028:DNA, Algal / Q000032:analysis / Q000235:genetics; D016054:DNA, Protozoan / Q000032:analysis / Q000235:genetics; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020761:rab1 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D048028:DNA, Algal; D016054:DNA, Protozoan; D020761:rab1 GTP-Binding Proteins