TY - JOUR
T1 - A single glutamic acid residue plays a key role in the transcriptional activation function of lambda repressor
AU - Bushman, Frederic D.
AU - Shang, Cheng
AU - Ptashne, Mark
N1 - Funding Information:
We thank members of the Ptashne laboratory for discussions and materials, Bob Craigie and Kiyoshi Mizuuchi for comments on the manuscript, and Craig Crews for construction of pCC2. We also thank Howard Holley for help with computer graphics, and Betsy Burkhardt for art work. This work was supported by National Institutes of Health grant GM22526.
PY - 1989/9/22
Y1 - 1989/9/22
N2 - Previous experiments have suggested that negative charge is an important aspect of the activating region of lambda repressor as it is for at least one class of eukaryotic transcriptional activators. Here we randomize amino acids in the activating region of repressor and assay the function of over 100 variants. We find that acidic residues at the four solvent-exposed positions on the surface of an α helix (helix 2 in the structure) together comprise a strong activating region. Only one of these acidic residues, however, is critical for activation, and at this position glutamate is strongly preferred to aspartate. At the three remaining positions, certain uncharged residues (different ones at each position) function as well as or better than the acidic residues. Basic residues, however, are highly detrimental to function at all four positions. Our mutagenesis studies also suggest limitations on amino acid substitutions that allow formation of the helix-turn-helix DNA binding motif found in repressor and in many other DNA binding regulatory proteins.
AB - Previous experiments have suggested that negative charge is an important aspect of the activating region of lambda repressor as it is for at least one class of eukaryotic transcriptional activators. Here we randomize amino acids in the activating region of repressor and assay the function of over 100 variants. We find that acidic residues at the four solvent-exposed positions on the surface of an α helix (helix 2 in the structure) together comprise a strong activating region. Only one of these acidic residues, however, is critical for activation, and at this position glutamate is strongly preferred to aspartate. At the three remaining positions, certain uncharged residues (different ones at each position) function as well as or better than the acidic residues. Basic residues, however, are highly detrimental to function at all four positions. Our mutagenesis studies also suggest limitations on amino acid substitutions that allow formation of the helix-turn-helix DNA binding motif found in repressor and in many other DNA binding regulatory proteins.
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U2 - 10.1016/0092-8674(89)90514-X
DO - 10.1016/0092-8674(89)90514-X
M3 - Article
C2 - 2570642
AN - SCOPUS:0024462398
SN - 0092-8674
VL - 58
SP - 1163
EP - 1171
JO - Cell
JF - Cell
IS - 6
ER -