Comparison of Transcription Elongation Rates of Three RNA Polymerases in Real Time

RNA
polymerases (RNAPs) across the bacterial kingdom have retained
a conserved structure and function. In spite of the remarkable similarity
of the enzyme in different bacteria, a wide variation is found in
the promoter–polymerase interaction, transcription initiation,
and termination. However, the transcription elongation was considered
to be a monotonic process, although the rate of elongation could vary
in different bacteria. Such variations in RNAP elongation rates could
be important to fine-tune the transcription, which in turn would influence
cellular metabolism and growth rates. Here, we describe a quantitative
study to measure the transcription rates for the RNAPs from three
bacteria, namely, Mycobacterium tuberculosis, Mycobacterium smegmatis, and Escherichia coli, which exhibit different growth
kinetics. The RNA synthesis rates of the RNAPs were calculated from
the real-time elongation kinetic profile using surface plasmon resonance
through a computational flux flow model. The computational model revealed
the modular process of elongation, with different rate profiles for
the three RNAPs. Notably, the transcription elongation rates of these
RNAPs followed the trend in the growth rates of these bacteria.