From all to (nearly) none: Tracing adaptin evolution in Fungi.
The five adaptor protein (AP) complexes function in cargo-selection and coat-recruitment stages of vesicular transport in eukaryotic cells. Much of what we know about AP complex function has come from experimental work usingSaccharomyces cerevisiaeas a model. Here, using a combination of comparative genomic and phylogenetic approaches we provide evolutionary context for the knowledge gained from this model system by searching the genomes of diverse fungi as well as a member of the sister group to all fungi,Fonticula alba,for presence of AP subunits. First, we demonstrate thatF. albacontains all five AP complexes; whereas, similar toS. cerevisiae,most fungi retain only AP-1 to 3. As exceptions, the glomeromyceteRhizophagus irregularismaintains a complete AP-4 and chytrid fungiSpizellomyces punctatusandBatrachochytrium dendrobatidisretain partial AP-4 complexes. The presence of AP-4 subunits in diverse fungi suggests that AP-4 has been independently lost up to seven times in the fungal lineage. In addition to the trend of loss in fungi, we demonstrate that the duplication that gave rise to the β subunits of the AP-1 and AP-2 complexes inS. cerevisiaeoccurred before the divergence ofF. albaand Fungi. Finally, our investigation into the AP complement of basal fungi (Microsporidia and Cryptomycota) demonstrates that while the cryptomyceteRozella allomycescontains an adaptin complement similar to other fungi, the extremely reduced Microsporidia retain, at most, a single cryptic AP complex in the absence of clathrin or any other putative AP-associated coat protein.
Department of Cell Biology; Faculty of Medicine and Dentistry; University of Alberta; Edmonton, Alberta, Canada.
Lael D
LD
Barlow
Department of Cell Biology; Faculty of Medicine and Dentistry; University of Alberta; Edmonton, Alberta, Canada.
Joel B
JB
Dacks
Department of Cell Biology; Faculty of Medicine and Dentistry; University of Alberta; Edmonton, Alberta, Canada.
Jeremy G
JG
Wideman
AP complex; Adaptins; Microsporidia; clathrin mediated endocytosis; evolutionary cell biology; fungal evolution; membrane trafficking