AtFKBP53 is a histone chaperone required for repression of ribosomal RNA gene expression in Arabidopsis.
Chromatin structure is important for controlling gene expression, but mechanisms underlying chromatin remodeling are not fully understood. Here we report that an FKBP (FK506 binding protein) type immunophilin, AtFKBP53, possesses histone chaperone activity and is required for repressing ribosomal gene expression in Arabidopsis. The AtFKBP53 protein is a multidomain FKBP with a typical peptidylprolyl isomerase (PPIase) domain and several highly charged domains. Using nucleosome assembly assays, we showed that AtFKBP53 has histone chaperone activity and the charged acidic domains are sufficient for the activity. We show that AtFKBP53 interacts with histone H3 through the acidic domains, whereas the PPIase domain is dispensable for histone chaperone activity or histone binding. Ribosomal RNA gene (18S rDNA) is overexpressed when AtFKBP53 activity is reduced or eliminated in Arabidopsis plants. Chromatin immunoprecipitation assay showed that AtFKBP53 is associated with the 18S rDNA gene chromatin, implicating that AtFKBP53 represses rRNA genes at the chromatin level. This study identifies a new histone chaperone in plants that functions in chromatin remodeling and regulation of transcription.
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Hong
H
Li
Sheng
S
Luan
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D047369:Chromatin Immunoprecipitation; D018506:Gene Expression Regulation, Plant; D006657:Histones / Q000378:metabolism; D020104:Immunophilins / Q000378:metabolism; D018832:Molecular Chaperones / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D012337:RNA, Ribosomal, 18S / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D022021:Tacrolimus Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; C549788:FKBP53 protein, Arabidopsis; D006657:Histones; D018832:Molecular Chaperones; D012337:RNA, Ribosomal, 18S; D011994:Recombinant Proteins; D012097:Repressor Proteins; D022021:Tacrolimus Binding Proteins; D020104:Immunophilins