HeLa nuclear protein recognizing DNA termini and translocating on DNA forming a regular DNA-multimeric protein complex.
Employing an exonuclease III protection assay we detected a protein in crude HeLa nuclear extracts binding, with apparent sequence specificity, to molecular ends of adenovirus type 2 (Ad2) DNA. This protein, designated nuclear factor IV (NFIV), was purified to homogeneity and was shown to be a hetero-dimer of 72,000 and 84,000 Mr. Binding to terminal Ad2 sequences was strongly enhanced by the presence of either of the sequence-specific DNA-binding proteins nuclear factor I and nuclear factor III. These proteins appeared to function as blockades for translocation of NFIV on DNA, thus producing apparent sequence specificity. In the absence of such a blockade, NFIV moved freely, without energy input, on any double-stranded DNA forming a regular DNA-multimeric protein complex as shown by methidiumpropyl EDTA footprinting and electron microscopy. Binding is completely dependent upon the presence of molecular ends. Evidence was obtained for a two-step mechanism in which termini are recognized by NFIV and used as a starting point for subsequent translocation. The possible functions of the protein in adenovirus DNA replication and in cellular processes requiring DNA termini are discussed.
Laboratory for Physiological Chemistry, State University of Utrecht, The Netherlands.
E
E
de Vries
W
W
van Driel
W G
WG
Bergsma
A C
AC
Arnberg
P C
PC
van der Vliet
D001483:Base Sequence; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases; D005809:Genes, Regulator; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008957:Models, Genetic; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013728:Terminator Regions, Genetic; D014178:Translocation, Genetic
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D005090:Exodeoxyribonucleases