title: Comparative genomics reveals selective distribution and domain organization of FYVE and PX domain proteins across eukaryotic lineages.
abstract: BACKGROUND
  Phosphatidylinositol 3-phosphate is involved in regulation of several key cellular processes, mainly endocytosis, signaling, nuclear processes, cytoskeletal remodelling, cell survival, membrane trafficking, phagosome maturation and autophagy. In most cases effector proteins bind to this lipid, using either FYVE or PX domain. These two domains are distributed amongst varied life forms such as virus, protists, fungi, viridiplantae and metazoa. As the binding ligand is identical for both domains, the goal of this study was to understand if there is any selectivity for either of these domains in different taxa. Further, to understand the different cellular functions that these domains may be involved in, we analyzed the taxonomic distribution of additional domains that associate with FYVE and PX.
  
  
  RESULTS
  There is selectivity for either FYVE or PX in individual genomes where both domains are present. Fungi and metazoa encode more PX, whereas streptophytes in viridiplantae encode more FYVE. Excess of FYVE in streptophytes results from proteins containing RCC1and DZC domains and FYVE domains in these proteins have a non-canonical ligand-binding site. Within a taxonomic group the selected domain associates with a higher number of other domains and is thus expected to discharge a larger number of cellular functions. Also, while certain associated domains are present in all taxonomic groups, most of them are unique to a specific group indicating that while certain common functions are discharged by these domains in all taxonomic groups, some functions appear to be group specific.
  
  
  CONCLUSIONS
  Although both FYVE and PX bind to PtdIns(3)P, genomes of different taxa show distinct selectivity of encoding either of the two. Higher numbers of taxonomic group specific domains co-occur with the more abundant domain (FYVE/PX) indicating that group-specific rare domain architectures might have emerged to accomplish certain group-specific functions.
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, Nadia 741252, West Bengal, India.
authors.forename: Sumana
authors.initials: S
authors.lastname: Banerjee
authors.forename: Soumalee
authors.initials: S
authors.lastname: Basu
authors.forename: Srimonti
authors.initials: S
authors.lastname: Sarkar
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics*; D000818:Animals; D055028:Comparative Genomic Hybridization; D005658:Fungi / Q000235:genetics; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010802:Phylogeny; D010944:Plants / Q000235:genetics; D011485:Protein Binding; D011506:Proteins / Q000235:genetics*; D020539:Sequence Analysis, Protein
chemical_list: D018129:Phosphatidylinositol Phosphates; D011506:Proteins; C055525:phosphatidylinositol 3-phosphate