title: Plant protein peptidase inhibitors: an evolutionary overview based on comparative genomics.
abstract: BACKGROUND
  Peptidases are key proteins involved in essential plant physiological processes. Although protein peptidase inhibitors are essential molecules that modulate peptidase activity, their global presence in different plant species remains still unknown. Comparative genomic analyses are powerful tools to get advanced knowledge into the presence and evolution of both, peptidases and their inhibitors across the Viridiplantae kingdom.
  
  
  RESULTS
  A genomic comparative analysis of peptidase inhibitors and several groups of peptidases in representative species of different plant taxonomic groups has been performed. The results point out: i) clade-specific presence is common to many families of peptidase inhibitors, being some families present in most land plants; ii) variability is a widespread feature for peptidase inhibitory families, with abundant species-specific (or clade-specific) gene family proliferations; iii) peptidases are more conserved in different plant clades, being C1A papain and S8 subtilisin families present in all species analyzed; and iv) a moderate correlation among peptidases and their inhibitors suggests that inhibitors proliferated to control both endogenous and exogenous peptidases.
  
  
  CONCLUSIONS
  Comparative genomics has provided valuable insights on plant peptidase inhibitor families and could explain the evolutionary reasons that lead to the current variable repertoire of peptidase inhibitors in specific plant clades.
authors.forename: María Estrella
authors.initials: ME
authors.lastname: Santamaría
authors.forename: Mercedes
authors.initials: M
authors.lastname: Diaz-Mendoza
authors.forename: Isabel
authors.initials: I
authors.lastname: Diaz
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus Montegancedo, Pozuelo de Alarcón, Madrid 28223, Spain. m.martinez@upm.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Martinez
mesh_terms: D019143:Evolution, Molecular; D023281:Genomics; D008958:Models, Molecular; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D057948:Viridiplantae / Q000201:enzymology / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D011480:Protease Inhibitors; D010447:Peptide Hydrolases