Evolution of the Kelch domain-containing family of protein phosphatases from plants and alveolate protists

CLAUDIO SLAMOVITS; SANTIAGO MORA GARCIA

Dublin

Congreso; Society for Molecular Evolution and Evolution; 2012

Society for Molecular Evolution and Evolution

Protein phosphatases are involved in essential cellular processes including signal transduction, enzymatic regulation, gene expression control and many others. Genomes of plants, green algae and alveolate protists encode one or more proteins with a C-terminal serine/threonine catalytic domain and an N-terminal domain containing several kelch repeats known as Kelch domain containing protein phosphatase (PPKL). BSL1, a PPKL from Arabidopsis thaliana has been studied experimentally and found to be involved in signaling by brassinosteroid hormones. However, presence of homologs in unicellular eukaryotes suggests that these proteins are also involved in more basic cellular functions. In addition to their relevance for the molecular biology of plant cells, this family constitute a potential chemotherapeutic target for apicomplexan parasites such as Plasmodium and Toxoplasma. PPKL is restricted to two eukaryotic lineages, the viridiplantae and alveolates, and appear to be highly conserved and ubiquitous in each of the two lineages. However, it is not clear if the PPKL genes from the two lineages have a common origin or if they resulted from independent fusions of a PP1-type catalytic domain with Kelch-type motifs. In addition, PPKL genes experienced several independent events of gene duplication at least in plants, apicomplexans and ciliates. In order to clarify the evolutionary history of this intriguing protein family and help determine their possible roles in plants and apicomplexan parasites we performed a phylogenetic analysis of the PPKL family using all available genomic and expressed data from plants, green algae, ciliates, apicomplexans and dinoagellates. Analysis of protein domain structure, indels and intron conservation in conjunction with the gene phylogeny indicates that the PPKL genes from the two lineages have a common origin, possibly moving to alveolates by endosymbiotic or lateral gene transfer. In addition, detailed analysis of selection on the four known plant PPKL paralogs shows that duplication and neofunctionalization is driving functional diversication in the PPKL family