Supercoiling-dependent site-specific binding of HU to naked Mu DNA.
Using HU chemical nucleases to probe HU-DNA interactions, we report here for the first time site-specific binding of HU to naked DNA. An unique feature of this interaction is the absolute requirement for negative DNA supercoiling for detectable levels of site-specific DNA binding. The HU binding site is the Mu spacer between the L1 and L2 transposase binding sites. Our results suggest recognition of an altered DNA structure which is induced by DNA supercoiling. We propose that recruitment of HU to this naked DNA site induces the DNA bending required for productive synapsis and transpososome assembly. Implications of HU as a supercoiling sensor with a potential in vivo regulatory role are discussed. Finally, using HU nucleases we have also shown that non-specific DNA binding by HU is stimulated by increasing levels of supercoiling.
Kobryn
K
K
Department of Biochemistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada.
Lavoie
B D
BD
Chaconas
G
G
D001426:Bacterial Proteins / Q000378:metabolism*; D010583:Bacteriophage mu / Q000235:genetics*; D001665:Binding Sites; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism*; D004279:DNA, Viral / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D009690:Nucleic Acid Conformation
D001426:Bacterial Proteins; D004278:DNA, Superhelical; D004279:DNA, Viral; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria