Suppressor-induced structural changes in a missense L-ribulokinase of Escherichia coli

A suppressor mutation specific for a missense codon in the L-ribulokinase structural gene of the L-arabinose operon of Escherichia coli B/r enhanced L-arabinose utilization by the strain containing the missense codon. Electrophoretic comparisons of the wild-type, missense, and suppressed missense L-ribulokinases indicated that the suppressor changed the structure of the missense kinase, thereby increasing its catalytic activity. Hyperinducibility imposed on an operator-distal gene by the missense codon was not affected by the suppressor mutation.