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. Author manuscript; available in PMC: 2020 Nov 1.
Published in final edited form as: Science. 2019 Nov 1;366(6465):589–593. doi: 10.1126/science.aay0934

Fig. 3. I-CoA inactivation impairs MCM repair.

Fig. 3.

(A) Scheme showing the role of the auxiliary proteins in cofactor loading/off-loading to/from MCM. (B and C) Enzyme-monitored turnover by human (B) and Mtb (C) MCM (black spectra) in the presence of M-CoA and human or Mtb CblA-GTP. Intermediate spectra (gray) were recorded every 2 min. Final spectra (red) were recorded at 1 hour. (D) Specific activity (SA) of human and Mtb MCM after 1-hour preincubation without or with M-CoA (red versus blue) and subsequent addition of the repair system (orange). (E and F) Addition of I-CoA to hMCM-AdoCbl [black, (E)] or Mtb MCM-AdoCbl [black, (F)] results in inactive enzyme (gray). Further incubationover 1 hour causes only modest spectral changes (red). (G and H) At the end of the experiments in (E) and (F), the repair system was added for 20 min to human (G) and Mtb (H) MCM. The increase in absorbance at 350 to 356 nm is indicative of OH2Cbl formation (red). (I) Same as in (D) but with I-CoA; in both panels, data represent means ± SD (n = 3).