ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Membrane transport is crucial to eukaryotic cell function and its evolution is likely to be critical for eukaryogenesis. Tetrameric adaptin complexes form part of the transport machinery, selecting cargo for transport through the late secretory and endocytic systems. With a few protistan exceptions, the majority of adaptin studies have been performed on animal and yeast models. Trypanosomatids and yeast have a minimal complement of adaptin genes, while humans and Arabidopsis show a moderate expansion. This expansion is functional, with adaptin subunit isoforms substituting combinatorially into their complex to provide novel localization. To address questions of evolution, parasitology and comparative cell biology, we examined the adaptin complexes of the sexually transmitted parasite Trichomonas vaginalis. In coordination with the T. vaginalis genome project at The Institute for Genomic Research, we identified all adaptin genes in the current 3.3X genome coverage data (). Surprisingly, T. vaginalis has massively and differentially expanded its adaptin arsenal, with six times as many genes as other unicellular organisms examined and three times as many multicellar organisms. Eight Trichomonas adaptins have been confirmed by cDNA, demonstrating concurrent expression of the same gene. Phylogenetic analysis shows that the duplications giving rise to the various adaptin subfamilies occurred prior to the last common ancestor of diverse protists. Our data provide important insight into the evolution of the adaptin complex and the complexity of the Trichomonas late secretory/endocytic system. The differential expansion may illustrate the relative functional importance of the adaptin subfamilies to Trichomonas and be a model in which to study the lesser expansion seen in other eukaryotes. Finally, the size of the expansion, and the concurrent expression of at least one gene, suggests that the combinatorial nature of the adaptin complex may be more important than previously expected.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_18.x
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