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.
de Vries
E
E
Laboratory for Physiological Chemistry, State University of Utrecht, The Netherlands.
van Driel
W
W
Bergsma
W G
WG
Arnberg
A C
AC
van der Vliet
P C
PC
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