Structural reorganization and the cooperative binding of single-stranded telomere DNA in Sterkiella nova.

ABSTRACT: In Sterkiella nova, alpha and beta telomere proteins bind cooperatively with single-stranded DNA to form a ternary alpha.beta.DNA complex. Association of telomere protein subunits is DNA-dependent, and alpha-beta association enhances DNA affinity. To further understand the molecular basis for binding cooperativity, we characterized several possible stepwise assembly pathways using isothermal titration calorimetry. In one path, alpha and DNA first form a stable alpha.DNA complex followed by the addition of beta in a second step. Binding energy accumulates with nearly equal free energy of association for each of these steps. Heat capacity is nonetheless dramatically different, with DeltaCp = -305 +/- 3 cal mol(-1) K(-1) for alpha binding with DNA and DeltaCp = -2010 +/- 20 cal mol(-1) K(-1)

SUBMITTER: Buczek P 

PROVIDER: S-EPMC2910716 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature