Characterization of a telomere-binding protein from Physarum polycephalum.
We have partially purified a nuclear protein (PPT) from Physarum polycephalum that binds to the extrachromosomal ribosomal DNA telomeres of this acellular slime mold. Binding is specific for the (T2AG3)n telomere repeats, as evidenced by nitrocellulose filter binding assays, by gel mobility shift assays with both DNA fragments and double-stranded oligonucleotides, and by DNase I footprinting. PPT is remarkably heat stable, showing undiminished binding activity after incubation at 90 degrees C. It sediments at 1.2S, corresponding to a molecular weight of about 10,000 (for a globular protein), and its binding activity is undiminished by incubation with RNase, suggesting that it is not a ribonucleoprotein. We hypothesize that PPT plays a structural role in telomeres, perhaps preventing nucleolytic degradation or promoting telomere extension by a telomere-specific terminal transferase.
Coren
J S
JS
Section of Genetics and Development, Cornell University, Ithaca, New York 14853.
Epstein
E M
EM
Vogt
V M
VM
D001483:Base Sequence; D015825:Chromosomes, Fungal / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010804:Physarum / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D003850:Deoxyribonuclease I