Figure 1

SpoIIIE can actively translocate and reach DNA ends even in the absence of SRS sequences. (A,B) AFM micrographs of SpoIIIE bound to SRS (DNA _SRS ) and to non-specific DNA (DNA _NS ) in the absence of ATP. Arrows indicate SpoIIIE complexes bound to SRS (green arrow in panel A) and to equivalent position replaced by non-specific DNA as a control (orange arrow in panel B). (C) Relative frequency of SpoIIIE binding to SRS (DNA _SRS ) or to the equivalent position replaced by non-specific DNA (DNA _NS , control). The position of SpoIIIE complexes in DNA was determined using a semi-automated algorithm and the relative frequency of SpoIIIE localization in bins of 50 nm was calculated (see Fig. S1A,B, Material and Methods and Supplementary Information). Error bars were obtained from the error propagation of Eq. 1 (n = 35). Upper scheme represents SpoIIIE bound to SRS and to the equivalent position replaced by non-specific DNA. (D,E) AFM micrographs of SpoIIIE complexes with DNA _SRS and DNA _NS substrates in the presence of ATP. Red arrows indicate SpoIIIE complexes that have reached the DNA ends by translocation. (F) Relative frequency of SpoIIIE reaching DNA ends by translocation in substrates with (DNA _SRS ) or without (DNA _NS ) SRS. The position of SpoIIIE complexes in DNA was determined as described in panel C (see Fig. S1C,D, n = 40). Upper scheme represents SpoIIIE reaching the DNA ends for substrates with or without SRS. Relative frequencies depicted in panel C were recalculated from previously published data¹¹.