This work was supported by the Canadian Cancer Society Research Institute Grant 020208 and by the National Sciences and Engineering Research Council of Canada.
Article first published online: 26 JUN 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Journal of Molecular Recognition
Volume 25, Issue 7, pages 414–426, July 2012
How to Cite
Beaulieu, M.-E., McDuff, F.-O., Frappier, V., Montagne, M., Naud, J.-F. and Lavigne, P. (2012), New structural determinants for c-Myc specific heterodimerization with Max and development of a novel homodimeric c-Myc b-HLH-LZ,. J. Mol. Recognit., 25: 414–426. doi: 10.1002/jmr.2203
This paper is dedicated to the memory of Dr. Mausumi Mazumdar.
- Issue published online: 26 JUN 2012
- Article first published online: 26 JUN 2012
- Manuscript Revised: 22 MAY 2012
- Manuscript Accepted: 22 MAY 2012
- Manuscript Received: 13 SEP 2011
- basic region-helix 1-loop-helix 2-leucine zipper;
- molecular recognition;
c-Myc must heterodimerize with Max to accomplish its functions as a transcription factor. This specific heterodimerization occurs through the b-HLH-LZ (basic region, helix 1-loop-helix 2-leucine zipper) domains. In fact, many studies have shown that the c-Myc b-HLH-LZ (c-Myc'SH) preferentially forms a heterodimer with the Max b-HLH-LZ (Max'SH). The primary mechanism underlying the specific heterodimerization lies on the destabilization of both homodimers and the formation of a more stable heterodimer. In this regard, it has been widely reported that c-Myc'SH has low solubility and homodimerizes poorly and that repulsions within the LZ domain account for the homodimer instability. Here, we show that replacing one residue in the basic region and one residue in Helix 1 (H1) of c-Myc'SH with corresponding residues conserved in b-HLH proteins confers to c-Myc'SH a higher propensity to form a stable homodimer in solution. In stark contrast to the wild-type protein, this double mutant (L362R, R367L) of the c-Myc b-HLH-LZ (c-Myc'RL) shows limited heterodimerization with Max'SH in vitro. In addition, c-Myc'RL forms highly stable and soluble complexes with canonical as well as non-canonical E-box probes. Altogether, our results demonstrate for the first time that structural determinants driving the specific heterodimerization of c-Myc and Max are embedded in the basic region and H1 of c-Myc and that these can be exploited to engineer a novel homodimeric c-Myc b-HLH-LZ with the ability of binding the E-box sequence autonomously and with high affinity. Copyright © 2012 John Wiley & Sons, Ltd.