Effect of arginine mutation of alanine-556 on DNA recognition of zinc finger protein Sp1.
Human transcription factor Sp1, which contains three Cys(2)His(2)-class zinc finger motives, specifically binds to the so-called GC box DNA. It has been indicated that finger 1 has a unique DNA-binding mode compared with fingers 2 and 3, or the Zif268 model. Therefore, we investigate the role of Ala at position 6 on the recognition helix, which is not responsible for guanine recognition and highly conserved among Sp1 family. Several Ala-556 mutations of Sp1 bind to DNA with different DNA-binding features. In particular, the Ala-->Arg substitution alters the DNA-binding contribution of the three zinc fingers in Sp1. In this case, the DNA-binding specificity of each finger decreases in the order 2>1>3. This result reveals that one amino acid in position 6 plays an important role not only for the selectivity to the putative finger 1 subsite, but also for the binding mode of the three fingers to each finger subsite. Probably, Ala-556 is indispensable to characterize the binding mode of the Sp1 zinc fingers, namely the diverse binding contribution of finger 1 and the rigid binding one of finger 3. In Sp1, the N-terminal finger 1 serves as a 'hinge finger'.
Matsushita
K
K
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Sugiura
Y
Y
D000409:Alanine; D019943:Amino Acid Substitution; D001120:Arginine; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013816:Thermodynamics; D016335:Zinc Fingers / Q000235:genetics
D009838:Oligodeoxyribonucleotides; D016329:Sp1 Transcription Factor; D004247:DNA; D001120:Arginine; D000409:Alanine