TRF1 is a dimer and bends telomeric DNA.
TRF1 is a mammalian telomeric protein that binds to the duplex array of TTAGGG repeats at chromosome ends. TRF1 has homology to the DNA-binding domain of the Myb family of transcription factors but, unlike most Myb-related proteins, TRF1 carries one rather than multiple Myb-type DNA-binding motifs. Here we show that TRF1 binds DNA as a dimer using a large conserved domain near the N-terminus of the protein for TRF1-TRF1 interactions. Dimerization was observed both in a complex with DNA and in the yeast two-hybrid assay. TRF1 dimers were found to require both Myb repeats for the formation of a stable complex with DNA, indicating a parallel between the DNA-binding mode of TRF1 and other Myb-related proteins. TRF1 was found to have a number of biochemical similarities to Rap1p, a distantly related DNA-binding protein that functions at telomeres in yeast. Rap1p and TRF1 both require two Myb motifs for DNA binding and both factors bind along their cognate telomeric sequences without showing strong cooperative interactions between adjacent proteins. Furthermore, TRF1 was found to bend its telomeric site to an angle of -120 degrees. Since Rap1p similarly distorts telomeric DNA, we propose that DNA bending is important for the function of telomeres in yeast and mammals.
Bianchi
A
A
The Rockefeller University, New York, NY 10021, USA.
Smith
S
S
Chong
L
L
Elias
P
P
de Lange
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D019281:Dimerization; D046911:Macromolecular Substances; D008322:Mammals; D009690:Nucleic Acid Conformation; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000089804:Shelterin Complex; D018411:Spodoptera; D016615:Telomere / Q000502:physiology*; D034501:Telomere-Binding Proteins; D035321:Telomeric Repeat Binding Protein 1; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C440829:RAP1 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; D035321:Telomeric Repeat Binding Protein 1; D014157:Transcription Factors; D004247:DNA