title: Prolyl isomerases in gene transcription.
abstract: BACKGROUND
  Peptidyl-prolyl isomerases (PPIases) are enzymes that assist in the folding of newly-synthesized proteins and regulate the stability, localization, and activity of mature proteins. They do so by catalyzing reversible (cis-trans) rotation about the peptide bond that precedes proline, inducing conformational changes in target proteins.
  
  
  METHODS
  This review will discuss how PPIases regulate gene transcription by controlling the activity of (1) DNA-binding transcription regulatory proteins, (2) RNA polymerase II, and (3) chromatin and histone modifying enzymes.
  
  
  CONCLUSIONS
  Members of each family of PPIase (cyclophilins, FKBPs, and parvulins) regulate gene transcription at multiple levels. In all but a few cases, the exact mechanisms remain elusive. Structure studies, development of specific inhibitors, and new methodologies for studying cis/trans isomerization in vivo represent some of the challenges in this new frontier that merges two important fields.
  
  
  CONCLUSIONS
  Prolyl isomerases have been found to play key regulatory roles in all phases of the transcription process. Moreover, PPIases control upstream signaling pathways that regulate gene-specific transcription during development, hormone response and environmental stress. Although transcription is often rate-limiting in the production of enzymes and structural proteins, post-transcriptional modifications are also critical, and PPIases play key roles here as well (see other reviews in this issue). This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 750 E Adams St., Syracuse, NY 13210 USA. Electronic address: haness@upstate.edu.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Hanes
mesh_terms: D000818:Animals; D002843:Chromatin / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology; D012319:RNA Polymerase II / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; D012319:RNA Polymerase II; D019696:Peptidylprolyl Isomerase
keywords: Ess1; Histone modification; Immunophilins; Pin1; RNA polymerase II CTD; Transcription regulation