The telomeric protein Pot1 from Schizosaccharomyces pombe binds ssDNA in two modes with differing 3' end availability.
Bottom Line: These experiments reveal one binding mode characterized by only subtle alternations to the individual OB-fold subdomain structures, resulting in an inaccessible 3' end of the ssDNA.The second binding mode, which has equivalent affinity, interacts differently with the 3' end, rendering it available for interaction with other proteins.These findings suggest a structural switch that contributes to telomere end-protection and length regulation.
Affiliation: Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA.Show MeSH
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Mentions: The linker between subdomains is unassigned in the Pot1-DBD+15mer spectrum due to either exchange broadening or overlap. Thus, we investigated its role in nucleic acid binding by creating a linker deletion construct. Deletion of 22 of the 25 amino acids that connect Pot1pN and Pot1pC had no negative impact upon binding affinity (Figure 2 and Supplementary Table S2)(43). In fact, affinity for both 12mer and 15mer increases slightly, likely due to a reduction in the entropic penalty of binding. These data suggest that the structurally uncharacterized linker does not play a role in nucleic acid binding, further confirming the validity of the individual subdomain structures.
Affiliation: Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA.