Multiple global conformational states of the hexameric RepA helicase of plasmid RSF1010 with different ssDNA-binding capabilities are induced by different numbers of bound nucleotides. Analytical ultracentrifugation and dynamic light scattering studies.

ABSTRACT: Global conformational transitions of the hexameric RepA helicase of plasmid RSF1010, induced by the nucleoside tri and di-phosphate binding, have been examined using analytical ultracentrifugation and dynamic light scattering techniques. The global structure of the RepA hexamer in solution, modeled as an oblate ellipsoid of revolution, is very different from its crystal structure, with the axial ratio of the ellipsoid being approximately 4.5 as compared to only approximately 2.4 in the crystal structure. The large axial ratio and the experimentally determined partial specific volume strongly suggest that, in solution, the diameter of the cross-channel of the hexamer is larger than approximately 17 A seen in the crystal. The global conformation of the helicase is modulated by a specific num

SUBMITTER: Marcinowicz A 

PROVIDER: S-EPMC3071628 | biostudies-literature | 2008 Jan

REPOSITORIES: biostudies-literature