Extended Data Fig. 5: CphA1 N domain structural homology, cyanophycin binding mode and mutants analysis.
From: Structures and function of the amino acid polymerase cyanophycin synthetase
a, Structure overlay of CphA1 with E. coli RNA polymerase alpha subunit (PDB code 4JK1), showing similarity in parts of their structures. b, Possible arrangement of cyanophycin that allows either its positive charges or negative charges to interact with αa or αb. c, Activity assays of TmCphA1 N domain mutants showing similar results to those observed for the equivalent SuCphA1 mutants (displayed in Fig. 5). n = 4 independent experiments. Data are presented as individual measurements and mean value, error bars represent SD values. d, Differential scanning fluorimetry melting curves and protein Tm values of CphA1 N domain mutants. The similarity of Tm values between wildtype and N domain mutants suggests that the observed differences in activity are a result of differences in interaction with cyanophycin rather than differences in protein stability. Additionally, the gel filtration profiles of the proteins during the purification process were all similar, again suggesting similar stability of wildtype and mutants. The values in the table represent the mean and SD of 3 independent measurements.
