Rice proteins that bind single-stranded G-rich telomere DNA.
In this work, we have identified and characterized proteins in rice nuclear extracts that specifically bind the single-stranded G-rich telomere sequence. Three types of specific DNA-protein complexes (I, II, and III) were identified by gel retardation assays using synthetic telomere substrates consisting of two or more single-stranded TTTAGGG repeats and rice nuclear extracts. Since each complex has a unique biochemical property and differs in electrophoretic mobility, at least three different proteins interact with the G-rich telomere sequences. These proteins are called rice G-rich telomere binding protein (RGBP) and none of them show binding affinity to double-stranded telomere repeats or single-stranded C-rich sequence. Changing one or two G's to C's in the TTTAGGG repeats abolishes binding activity. RGBPs have a greatly reduced affinity for human and Tetrahymena telomeric sequence and do not efficiently bind the cognate G-rich telomere RNA sequence UUUAGGG. Like other telomere binding proteins, RGBPs are resistant to high salt concentrations. RNase sensitivity of the DNA-protein interaction. In this assay, we observed a novel complex (complex III) in gel retardation assays which did not alter the mobilities or the band intensities of the two pre-existing complexes (I and II). The complex III, in addition to binding to telomeric sequences, has a binding affinity to rice nuclear RNA, whereas two other complexes have a binding affinity to only single-stranded G-rich telomere DNA. Taken together, these studies suggest that RGBPs are new types of telomere-binding proteins that bind in vitro to single-stranded G-rich telomere DNA in the angiosperms.
Kim
J H
JH
Department of Biology, Yonsei University, Seoul, Korea.
Kim
W T
WT
Chung
I K
IK
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism; D015345:Oligonucleotide Probes / Q000235:genetics; D012275:Oryza / Q000378:metabolism; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D012091:Repetitive Sequences, Nucleic Acid; D012965:Sodium Chloride; D016615:Telomere / Q000235:genetics* / Q000378:metabolism*
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D015345:Oligonucleotide Probes; D010940:Plant Proteins; D012965:Sodium Chloride