Helix-destabilizing properties of the adenovirus DNA-binding protein.
The adenovirus DNA-binding protein (DBP) is a multifunctional protein that is essential for viral DNA replication. DBP binds both single-stranded and double-stranded DNA as well as RNA in a sequence-independent manner. Previous studies showed that DBP does not promote melting of duplex poly(dA-dT) in contrast to prokaryotic single-strand-binding proteins. However, here we show that DBP can displace oligonucleotides annealed to single-stranded M13 DNA. Depending upon the DBP concentration, strands of at least 200 nucleotides can be unwound. Although unwinding of short (17-bp), fully duplex DNA is facilitated by DBP, unwinding of larger (28-bp) duplexes is only possible if single-stranded protruding ends are present. These protruding ends must be at least 4 nucleotides long for optimal unwinding, and both 5' and 3' single-stranded overhangs suffice. DBP-promoted strand displacement is sensitive to MgCl2 and NaCl and not dependent upon ATP. Our results suggest that DBP, through formation of a protein chain on the displaced strand, may destabilize duplex DNA ahead of the replication fork, thereby assisting in strand displacement during replication.
Zijderveld
D C
DC
Laboratory for Physiological Chemistry, University of Utrecht, The Netherlands.
van der Vliet
P C
PC
D000256:Adenoviridae / Q000201:enzymology*; D017502:Adenovirus E2 Proteins / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015636:Magnesium Chloride / Q000494:pharmacology; D008954:Models, Biological; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009841:Oligonucleotides / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology
D017502:Adenovirus E2 Proteins; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D015636:Magnesium Chloride; D012965:Sodium Chloride; D004265:DNA Helicases