Fig. 3

Mutation library construction of CcpA. (A) The top 40 mutants with the highest absorbance at 270 nm were screened from the CcpA mutant library by high-throughput screening. (B) The cytidine titers of the screened mutant libraries D1 (E43D) and D2 (S77A/M103L/S281A/P314K), and the combined mutant BSNX4-DM of the two domains (E43D/S77A/M103L/S281A/P314K). (C) In the wild-type CcpA domain D1, the residue E at position 34 was mutated to D. In domain D2, the residue S at position 77 is mutated to A; the residue M at position 103 is mutated to L; the residue S at position 281 is mutated to A; and the residue P at position 314 is mutated to K