  To mitigate errors induced by the cell's heterogeneous noisy environment, its
main information channels and production networks utilize the kinetic
proofreading (KPR) mechanism. Here, we examine two extensively-studied KPR
circuits, DNA replication by the T7 DNA polymerase and translation by the E.
coli ribosome. Using experimental data, we analyze the performance of these two
vital systems in light of the fundamental bounds set by the recently-discovered
thermodynamic uncertainty relation (TUR), which places an inherent trade-off
between the precision of a desirable output and the amount of energy
dissipation required. We show that the DNA polymerase operates close to the TUR
lower bound, while the ribosome operates $\sim5$ times farther from this bound.
This difference originates from the enhanced binding discrimination of the
polymerase which allows it to operate effectively as a reduced reaction cycle
prioritizing correct product formation. We show that approaching this limit
also decouples the thermodynamic uncertainty factor from speed and error,
thereby relaxing the accuracy-speed trade-off of the system. Altogether, our
results show that operating near this reduced cycle limit not only minimizes
thermodynamic uncertainty, but also results in global performance enhancement
of KPR circuits.
