DDP1, a single-stranded nucleic acid-binding protein of Drosophila, associates with pericentric heterochromatin and is functionally homologous to the yeast Scp160p, which is involved in the control of cell ploidy.
The centromeric dodeca-satellite of Drosophila forms altered DNA structures in vitro in which its purine-rich strand (G-strand) forms stable fold-back structures, while the complementary C-strand remains unstructured. In this paper, the purification and characterization of DDP1, a single-stranded DNA-binding protein of high molecular mass (160 kDa) that specifically binds the unstructured dodeca-satellite C-strand, is presented. In polytene chromosomes, DDP1 is found located at the chromocentre associated with the pericentric heterochromatin but its distribution is not constrained to the dodeca-satellite sequences. DDP1 also localizes to heterochromatin in interphase nuclei of larval neuroblasts. During embryo development, DDP1 becomes nuclear after cellularization, when heterochromatin is fully organized, being also associated with the condensed mitotic chromosomes. In addition to its localization at the chromocentre, in polytene chromosomes, DDP1 is also detected at several sites in the euchromatic arms co-localizing with the heterochromatin protein HP1. DDP1 is a multi-KH domain protein homologous to the yeast Scp160 protein that is involved in the control of cell ploidy. Expression of DDP1 complements a Deltascp160 deletion in yeast. These results are discussed in view of the possible contribution of DNA structure to the structural organization of pericentric heterochromatin.
Departament de Biologia Molecular i Cel.lular, Centre d'Investigació i Desenvolupament-CSIC, Jordi Girona Salgado 18-26, 08034 Barcelona, Spain.
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004276:DNA, Satellite / Q000235:genetics / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011003:Ploidies; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015003:Yeasts / Q000235:genetics
D004276:DNA, Satellite; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C491076:Dp1 protein, Drosophila; D029721:Drosophila Proteins; D005656:Fungal Proteins; D006570:Heterochromatin; D019476:Insect Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; C097262:SCP160 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C118122:TIMM8A protein, human