DNA binding by the KP repressor protein inhibits P-element transposase activity in vitro.
P elements are a family of mobile DNA elements found in Drosophila. P-element transposition is tightly regulated, and P-element-encoded repressor proteins are responsible for inhibiting transposition in vivo. To investigate the molecular mechanisms by which one of these repressors, the KP protein, inhibits transposition, a variety of mutant KP proteins were prepared and tested for their biochemical activities. The repressor activities of the wild-type and mutant KP proteins were tested in vitro using several different assays for P-element transposase activity. These studies indicate that the site-specific DNA-binding activity of the KP protein is essential for repressing transposase activity. The DNA-binding domain of the KP repressor protein is also shared with the transposase protein and resides in the N-terminal 88 amino acids. Within this region, there is a C2HC putative metal-binding motif that is required for site-specific DNA binding. In vitro the KP protein inhibits transposition by competing with the transposase enzyme for DNA-binding sites near the P-element termini.
Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, CA 94720-3204, USA.
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D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004251:DNA Transposable Elements / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D019281:Dimerization; D004331:Drosophila melanogaster / Q000235:genetics*; D008670:Metals; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D019895:Transposases / Q000037:antagonists & inhibitors*
D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D008670:Metals; D004247:DNA; D019895:Transposases