Secondary structure of the homeo domain of yeast alpha 2 repressor determined by NMR spectroscopy.
The yeast alpha 2 protein is a regulator of cell type in Saccharomyces cerevisiae. It represses transcription of a set of target genes by binding to an operator located upstream of each of these genes. The alpha 2 protein shares weak sequence similarity with members of the homeo domain family; the homeo domain is a 60-amino-acid segment found in many eukaryotic transcriptional regulators. In this paper we address the question of whether alpha 2 is structurally related to prototypical members of the homeo domain family. We used solution 1H and 15N nuclear magnetic resonance [NMR] spectroscopy to determine the secondary structure of an 83-amino-acid residue fragment of alpha 2 that contains the homeo domain homology. We have obtained resonance assignments for the backbone protons and nitrogens of the entire 60-residue region of the putative homeo domain and for most of the remainder of the alpha 2 fragment. The secondary structure was determined by using NOE connectivities between backbone protons, 3JHN-H alpha coupling constants, and dynamical information from the hydrogen exchange kinetics of the backbone amides. Three helical segments exist in the alpha 2 fragment consisting of residues 11-23, 32-42, and 46-60 (corresponding to residues 138-150, 159-169, and 173-187 of the intact protein). The positions of these three helices correspond extremely well to those of the Drosophila Antennapedia (Antp) and engrailed (en) homeo domains, whose three-dimensional structures have recently been determined by NMR spectroscopy and X-ray crystallography, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Phillips
C L
CL
Institute of Molecular Biology, University of Oregon, Eugene 98403.
Vershon
A K
AK
Johnson
A D
AD
Dahlquist
F W
FW
D000595:Amino Acid Sequence; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D005800:Genes, Fungal; D005801:Genes, Homeobox; D018398:Homeodomain Proteins; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid
D004271:DNA, Fungal; D005656:Fungal Proteins; D018398:Homeodomain Proteins; C062928:MATA2 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins