Coat protein of cauliflower mosaic virus binds to ssDNA.
Alkali-denatured cauliflower mosaic virus (CaMV) virions incorporated ssDNA, added exogenously, into multimolecular complexes during dialysis against a neutral buffer. CaMV coat protein binding to tracer DNA, assessed by gel electrophoresis and autoradiography, was highly cooperative as judged by the absence of intermediate-sized complexes. The incorporation of labelled BglII fragments of a plasmid containing CaMV DNA into complexes was prevented by the presence of 0.16 g/l unlabelled calf thymus DNA. Lower concentrations of competitor DNA allowed binding of some BglII fragments although preventing the binding of others. The self-annealing poly(dI-dC) was much less efficient than calf thymus DNA in preventing the incorporation of fragments into complexes, suggesting a binding preference for ss- over dsDNA. In addition, dsDNA, minimally cross-linked to prevent strand separation, was bound only weakly. End-labelled ssDNA fragments in complexes were partially protected against DNase I. The nucleic acid-binding activity of CaMV coat protein may be responsible for the organization of replication complexes, the precursors to virion particles.
Thompson
S R
SR
Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater 74078-0454.
Melcher
U
U
D001667:Binding, Competitive; D001937:Brassica / Q000382:microbiology; D002213:Capsid / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D009029:Mosaic Viruses / Q000378:metabolism*
D004277:DNA, Single-Stranded; D004279:DNA, Viral; D003850:Deoxyribonuclease I