Alleviation of histone H1-mediated transcriptional repression and chromatin compaction by the acidic activation region in chromosomal protein HMG-14.
Histone H1 promotes the generation of a condensed, transcriptionally inactive, higher-order chromatin structure. Consequently, histone H1 activity must be antagonized in order to convert chromatin to a transcriptionally competent, more extended structure. Using simian virus 40 minichromosomes as a model system, we now demonstrate that the nonhistone chromosomal protein HMG-14, which is known to preferentially associate with active chromatin, completely alleviates histone H1-mediated inhibition of transcription by RNA polymerase II. HMG-14 also partially disrupts histone H1-dependent compaction of chromatin. Both the transcriptional enhancement and chromatin-unfolding activities of HMG-14 are mediated through its acidic, C-terminal region. Strikingly, transcriptional and structural activities of HMG-14 are maintained upon replacement of the C-terminal fragment by acidic regions from either GAL4 or HMG-2. These data support the model that the acidic C terminus of HMG-14 is involved in unfolding higher-order chromatin structure to facilitate transcriptional activation of mammalian genes.
Ding
H F
HF
Dana-Farber Cancer Institute, and Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Bustin
M
M
Hansen
U
U
D000595:Amino Acid Sequence; D002843:Chromatin / Q000378:metabolism*; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D012319:RNA Polymerase II / Q000378:metabolism; D012367:RNA, Viral / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins; D017384:Sequence Deletion; D013539:Simian virus 40 / Q000235:genetics; D014158:Transcription, Genetic / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology
D002843:Chromatin; D006609:High Mobility Group Proteins; D006657:Histones; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D012319:RNA Polymerase II