Journal Article

Interactions between HMG boxes

Susann Taudte, Hong Xin, Anthony J. Bell and Neville R. Kallenbach

in Protein Engineering, Design and Selection

Volume 14, issue 12, pages 1015-1023
Published in print December 2001 | ISSN: 1741-0126
Published online December 2001 | e-ISSN: 1741-0134 | DOI: https://dx.doi.org/10.1093/protein/14.12.1015
Interactions between HMG boxes

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Many proteins consist of subdomains that can fold and function independently. We investigate here the interaction between the two high mobility group (HMG) box subdomains of the nuclear protein rHMG1. An HMG box is a conserved amino acid sequence of approximately 80 amino acids rich in basic, aromatic and proline side chains that is active in binding DNA in a sequence or structure-specific manner. In the case of HMG1, each box can bind structural DNA substrates including four-way junctions (4WJs) and branched or kinked DNA duplexes. Since proteins containing up to six HMG boxes are known, the question arises whether linking subdomains together influences the folding or function of individual boxes. In an effort to understand interactions between individual DNA-binding domains in HMG1, we created new fusion proteins: one is an inversion of the order of the AB di-domain in HMG1 (BA); in the second, we added a third A domain C-terminal to the AB di-domain (ABA). Pairs of boxes, AB or BA, behave similarly and are functionally active. By contrast, the ABA triple subdomain construct is partially unfolded and is less active than individual boxes or di-domains. Thus, long-range inter-domain effects can influence the activity of HMG boxes.

Keywords: circular dichroism; DNA binding; high mobility group protein I; protein stability; subdomain shuffling

Journal Article.  5444 words.  Illustrated.

Subjects: Proteins

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