Histone chaperones, a supporting role in the limelight.
In eukaryotic cells, highly basic histone proteins are associated with the DNA to form the nucleosome, the fundamental unit of chromatin. Histones are closely escorted by histone chaperones from their point of synthesis up to their delivery site. We will present an overview of the histone chaperones identified to date with their various roles, in an attempt to highlight their importance in cellular metabolism. Nucleoplasmin will illustrate a role in histone storage and Nap-1, a histone translocator. CAF-1 and Hira will provide examples of distinct histone deposition factors coupled to and uncoupled from DNA synthesis, respectively, while Asf1 could act as a histone donor. We then will illustrate with two examples how histone chaperones can be associated with chromatin remodeling activities. Finally, we will discuss how the RbAp46/48 proteins, as escort factors, are part of multiple complexes with various functions. Based on these examples, we will propose a scheme in which the diverse roles of histone chaperones are integrated within an assembly line for chromatin formation and regulation. Finally, we discuss how these chaperones may have more than a supporting role in a histone metabolic pathway.
Loyola
Alejandra
A
Institut Curie/Section de Recherche, UMR 21826, rue d'Ulm, 75231 Paris Cedex 05, France.
Almouzni
Genevieve
G
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D002868:Chromosomal Proteins, Non-Histone; D056488:Histone Chaperones; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056489:Nucleoplasmins; D056490:Nucleosome Assembly Protein 1; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D056505:Retinoblastoma-Binding Protein 4; D056524:Retinoblastoma-Binding Protein 7; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
C491641:ASF1A protein, human; C491640:ASF1B protein, human; C491639:Asf1b protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; C086057:HIRA protein, human; C484187:Hira protein, mouse; D056488:Histone Chaperones; D006657:Histones; D018832:Molecular Chaperones; C533557:NAP1L1 protein, human; C533558:Nap1l1 protein, mouse; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D056490:Nucleosome Assembly Protein 1; D009707:Nucleosomes; D010750:Phosphoproteins; D011506:Proteins; C082637:RBBP4 protein, human; C490746:RBBP7 protein, human; C489969:Rbbp4 protein, mouse; D056505:Retinoblastoma-Binding Protein 4; D056524:Retinoblastoma-Binding Protein 7; D014157:Transcription Factors