High mobility group proteins HMG-1 and HMG-I/Y bind to a positive regulatory region of the pea plastocyanin gene promoter |
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| Authors: | Carl I Webster Leonard C Packman Keng-Hock Pwee John C Gray |
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| Institution: | Cambridge Centre for Molecular Recognition and Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK;Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK |
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| Abstract: | A 268 bp region (P268) of the pea plastocyanin gene promoter responsible for high-level expression has been shown to interact with the high mobility group proteins HMG-1 and HMG-I/Y isolated from pea shoot chromatin. cDNAs encoding an HMG-1 protein of 154 amino acid residues containing a single HMG-box and a C-terminal acidic tail and an HMG-I/Y-like protein of 197 amino acid residues containing four AT-hooks have been isolated and expressed in Escherichia coli to provide large amounts of full-length proteins. DNase I footprinting identified eight binding sites for HMG-I/Y and six binding sites for HMG-1 in P268. Inhibition of binding by the antibiotic distamycin, which binds in the minor groove of A/T-rich DNA, revealed that HMG-I/Y binding was 400-fold more sensitive than HMG-1 binding. Binding-site selection from a pool of random oligonucleotides indicated that HMG-I/Y binds to oligonucleotides containing stretches of five or more A/T bp and HMG-1 binds preferentially to oligonucleotides enriched in dinucleotides such as TpT and TpG. |
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