Structure of a Leu3-DNA complex: recognition of everted CGG half-sites by a Zn2Cys6 binuclear cluster protein.
Gal4 is the prototypical Zn2Cys6 binuclear cluster transcriptional regulator that binds as a homodimer to DNA containing inverted CGG half-sites. Leu3, a member of this protein family, binds to everted (opposite polarity to inverted) CGG half-sites, and an H50C mutation within the Leu3 Zn2Cys6 binuclear motif abolishes its transcriptional repression function without impairing DNA binding. We report the X-ray crystal structures of DNA complexes with Leu3 and Leu3(H50C) and solution DNA binding studies of selected Leu3 mutant proteins. These studies reveal the molecular details of everted CGG half-site recognition, and suggest a role for the H50C mutation in transcriptional repression. Comparison with the Gal4-DNA complex shows an unexpected conservation in the DNA recognition mode of inverted and everted CGG half-sites, and points to a critical function of a linker region between the Zn2Cys6 binuclear cluster and dimerization regions in DNA binding specificity. Broader implications of these findings are discussed.
Fitzgerald
Mary X
MX
The Wistar Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Rojas
Jeannie R
JR
Kim
John M
JM
Kohlhaw
Gunter B
GB
Marmorstein
Ronen
R
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015032:Zinc / Q000737:chemistry*
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C063667:LEU3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D006639:Histidine; D004247:DNA; D015032:Zinc; D003545:Cysteine