Figure 9
From: Rap1 and Cdc13 have complementary roles in preventing exonucleolytic degradation of telomere 5′ ends
Schematic figure summarizing the results of this work and how it is proposed to relate to different in vivo situations. (a) Shows the different substrate tested with Cdc13 or Rap1 pre-bound at their respective MBS at various distances relative the ds-ss junction. “ + ” indicates protection, while “−’’ indicates no protection. (b) Protection by Rap1 when the 3′ overhang is very short and unable to accommodate Cdc13 binding. (c) Protection by Rap1 in a hypothetical situation where Cdc13 is bound very far away from the ds-ss junction (longer than tested here). (d) Protection may be provided by Cdc13 alone when the 3′ overhang accommodates its binding. (e) The wild type Rap1 DBD337–582 is firmly attached to its MBS, and fully protects the 5′ end from degradation by λ-exonuclease. (f) The Rap1 wrapping loop mutant DBD337–556 is only partly attached to the MBS, leaving the 5′ end accessible to λ-exonuclease, which cleaves off the first 3 nt of DNA before being halted at a site where the mutant DBD is more firmly attached.
