PROPERTIES OF RECA COMPLEXES WITH HOMOPOLYMERIC DNA STRANDS DEPEND ON SEQUENCE COMPLEMENTARITY - IMPLICATIONS FOR THE MECHANISM OF STRAND EXCHANGE
Artikel i vetenskaplig tidskrift, 1994

We have characterised complexes between RecA and single-stranded homopolynucleotides by linear dichroism spectroscopy and small angle neutron scattering to investigate base pairing possibilities among DNA strands bound in a RecA filament. We find that in the presence of the non-hydrolysable cofactor ATP gamma S, and very likely also in the presence of ATP, a RecA fiber has three distinct DNA binding sites, each of which can bind one strand of DNA at a stoichiometry of three nucleotides per RecA monomer. The structural and hydrodynamic properties of the complexes are found to depend on the number of strands bound and on sequence complementarity among the strands. For example, RecA-[homopolymer](3)-ATP gamma S complexes aggregate when either of the strands bound in sites I and II is complementary to the strand bound in site III. We have also studied the RecA catalysed annealing of complementary homopolymers and find it to be most efficient when two strands of one homopolymer are bound per RecA filament prior to the addition of the complementary homopolymer. These results suggest that a DNA strand bound in site III can base-pair with either of the strands in sites I and II, whereas the latter strands are unable to base-pair with each other.

stoichiometry

escherichia-coli

binding

angle neutron-scattering

helical filaments

flow-oriented solution

linear dichroism

homologous recombination

electron-microscopy

protein

Författare

Mikael Kubista

Institutionen för biokemi och biofysik

Bengt Nordén

Institutionen för fysikalisk kemi

M. Takahashi

Nucleosides and Nucleotides

0732-8311 (ISSN) 1532-2335 (eISSN)

Vol. 13 1-3 753-772

Ämneskategorier

Biokemi och molekylärbiologi

DOI

10.1080/15257779408013277