TY - JOUR
T1 - Analysis of the Myc and Max interaction specificity with λ repressor-HLH domain fusions
AU - Marchetti, Alessandra
AU - Abril-Marti, Marian
AU - Illi, Barbara
AU - Cesareni, Gianni
AU - Nasi, Sergio
PY - 1995
Y1 - 1995
N2 - The basic helix-loop-helix domain (bHLH) is present in a large class of transcriptional regulators involved in developmental processes and oncogenesis. It determines DNA binding and specific homo- and heterodimeric protein associations, crucial for protein function. Myc and Max belong to a subset of HLH proteins, containing a leucine zipper (LZ) adjacent to the bHLH domain. They differ in dimerization and functional properties such as DNA binding and transcriptional activation, and their association is required for malignant transformation by Myc. To analyze the interaction specificity of Myc and Max bHLH-LZ domains, we developed a simple Escherichia coli genetic system, which uses the amino-terminal λ phage cI repressor as a reporter for dimerization and allows an easy detection of dimeric interactions. By reciprocal exchanges of different Myc and Max subdomains (helix 1, helix 2 and leucine zipper), we showed that the recognition specificity of Max homodimers as well as of Myc/Max heterodimers is entirely determined by the helix 2-leucine zipper region, the major role being played by the leucine zipper. The Myc LZ was found to prevent homodimeric interactions, thus explaining Myc inability to homodimerize efficiently Moreover, we showed that the system is valid as well for reproducing the interaction of HLH proteins not containing a leucine zipper and that the chimerical proteins maintain sequence-specific DNA binding.
AB - The basic helix-loop-helix domain (bHLH) is present in a large class of transcriptional regulators involved in developmental processes and oncogenesis. It determines DNA binding and specific homo- and heterodimeric protein associations, crucial for protein function. Myc and Max belong to a subset of HLH proteins, containing a leucine zipper (LZ) adjacent to the bHLH domain. They differ in dimerization and functional properties such as DNA binding and transcriptional activation, and their association is required for malignant transformation by Myc. To analyze the interaction specificity of Myc and Max bHLH-LZ domains, we developed a simple Escherichia coli genetic system, which uses the amino-terminal λ phage cI repressor as a reporter for dimerization and allows an easy detection of dimeric interactions. By reciprocal exchanges of different Myc and Max subdomains (helix 1, helix 2 and leucine zipper), we showed that the recognition specificity of Max homodimers as well as of Myc/Max heterodimers is entirely determined by the helix 2-leucine zipper region, the major role being played by the leucine zipper. The Myc LZ was found to prevent homodimeric interactions, thus explaining Myc inability to homodimerize efficiently Moreover, we showed that the system is valid as well for reproducing the interaction of HLH proteins not containing a leucine zipper and that the chimerical proteins maintain sequence-specific DNA binding.
KW - λ repressor
KW - Dimerization specificity
KW - HLH domains
KW - Myc and Max
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U2 - 10.1006/jmbi.1995.0241
DO - 10.1006/jmbi.1995.0241
M3 - Article
C2 - 7752223
AN - SCOPUS:0029005260
VL - 248
SP - 541
EP - 550
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 3
ER -