Base sequence discrimination by zinc-finger DNA-binding domains.
Zinc fingers constitute important eukaryotic DNA-binding domains, being present in many transcription factors. The Cys2/His2 zinc-finger class has conserved motifs of 28-30 amino acids which are usually present as tandem repeats. The structure of a Cys2/His2 zinc finger has been determined by nuclear magnetic resonance, but details of its interaction with DNA were not established. Here we identify amino acids governing DNA-binding specificity using in vitro directed mutagenesis guided by similarities between the zinc fingers of transcription factors Sp1 and Krox-20. Krox-20 is a serum-inducible transcription activator which is possibly involved in the regulation of hindbrain development; it contains three zinc fingers similar to those of Sp1 and binds to a 9-base-pair target sequence which is related to that of Sp1. Our results show that each finger spans three nucleotides and indicate two positions in Krox-20 zinc fingers that are important for base-pair selectivity. Modelling with molecular graphics suggests that these residues could bind directly with the bases and that other amino acid-base contacts are also possible.
Nardelli
J
J
Laboratoire de Génétique Moléculaire, CNRS D 1302, Ecole Normale Supérieure, Paris, France.
Gibson
T J
TJ
Vesque
C
C
Charnay
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003196:Computer Graphics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D051767:Early Growth Response Protein 2; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism*; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; D016329:Sp1 Transcription Factor; D014157:Transcription Factors