Effect of alteration of translation error rate on enzyme microheterogeneity as assessed by variation in single molecule electrophoretic mobility and catalytic activity

The role of translation error for Escherichia coli individual β-galactosidase molecule catalytic and electrophoretic heterogeneity was investigated using CE-LIF. An E. coli rpsL mutant with a hyperaccurate translation phenotype produced enzyme molecules that exhibited significantly less catalytic heterogeneity but no reduction of electrophoretic heterogeneity. Enzyme expressed with streptomycin-induced translation error had increased thermolability, lower activity, and no significant change to catalytic or electrophoretic heterogeneity. Modeling of the electrophoretic behaviour of β-galactosidase suggested that variation of the hydrodynamic radius may be the most significant contributor to electrophoretic heterogeneity.