Illustration of the TrpB kinetic characterization. (a)
TrpB stand-alone
activities (in terms of kcat) for LBCA,
SPM3, SPM6, and SPM8, shown as multiples of the ANC3 activity (logarithmic
scale). While the reference stand-alone LBCA TrpB is 17.4-fold more
active than ANC3 TrpB, the new TrpB designs SPM3, SPM6, and SPM8 are
1.1-fold, 7-fold, and 5.4-fold more active than ANC3 TrpB. (b) Activity
differences (in terms of kcat) between
isolated and TrpA-complexed ANC3, LBCA, SPM3, SPM6, and SPM8 TrpB
enzymes. TrpS complex formation leads to an increase in the catalytic
activities of ANC3, SPM3, SPM6, and SPM8 TrpB enzymes by factors of
30.2, 26.3, 5.5, and 1.9, and a decrease for LBCA TrpB by a factor
of 8.4. The bar height represents the average value from two independent
measurements, which are shown as gray dots. All catalytic constants
are listed in Tables S2–S5.