Molecular structure of chromosomal proteins HMG-14 and HMG-17: definition of a transcriptional enhancement domain distinct from the nucleosomal binding domain

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Item Type:	Article
Title:	Molecular structure of chromosomal proteins HMG-14 and HMG-17: definition of a transcriptional enhancement domain distinct from the nucleosomal binding domain
Creators Name:	Trieschmann, L., Postnikov, Y., Rieckers, A. and Bustin, M.
Abstract:	Chromosomal proteins HMG-14 and HMG-17 are the only known nuclear proteins which specifically bind to the nucleosome core particle and are implicated in the generation and/or maintenance of structural features specific to active chromatin. The two proteins facilitate polymerase II and III transcription from in vitro- and in vivo-assembled circular chromatin templates. Here we used deletion mutants and specific peptides to identify the transcriptional enhancement domain and delineate the nucleosomal binding domain of the HMG-14 and -17 proteins. Deletion of the 22 C-terminal amino acids of HMG-17 or 26 C-terminal amino acids of HMG-14 reduces significantly the ability of the proteins to enhance transcription from chromatin templates. In contrast, N-terminal truncation mutants had the same transcriptional enhancement activity as the full-length proteins. We conclude that the negatively charged C-terminal region of the proteins is required for transcriptional enhancement. Chromatin transcription enhancement assays, which involve binding competition between the full-length proteins and peptides derived from their nucleosomal binding regions, indicate that the minimal nucleosomal binding domain of human HMG-17 is 24 amino acids long and spans residues 17 to 40. The results suggest that HMG-14 and -17 proteins have a modular structure and contain distinct functional domains.
Keywords:	Amino Acid Sequence, Binding Sites, Competitive Binding, Chromatin, High Mobility Group Proteins, Kinetics, Molecular Sequence Data, Mutagenesis, Nucleosomes, Oocytes, Peptide Fragments, 5S Ribosomal RNA, Recombinant Proteins, Sequence Deletion, Amino Acid Sequence Homology, Genetic Transcription, Animals, Xenopus
Source:	Molecular and Cellular Biology
ISSN:	0270-7306
Publisher:	American Society for Microbiology
Volume:	15
Number:	12
Page Range:	6663-6669
Date:	December 1995
Official Publication:	http://mcb.asm.org/cgi/content/abstract/15/12/6663
PubMed:	View item in PubMed

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