Concluding remarks
Apo - and holo -PlzA function differently in the vertebrate
and tick phases of the enzootic cycle of B. burgdorferi(14,52,55-57). We and others have suggested that the effector functions
of apo -PlzA and holo -PlzA reflect distinct activities and
interaction partners (14,47,53,54,57). Here, we demonstrate that
c-di-GMP modulates the RNA strand displacement and unwinding activity of
PlzA, suggesting these activities may be important for the vertebrate
phase of the life cycle, but not the tick phase. Conversely, PlzA has
c-di-GMP-independent RNA annealing activity, and we postulate that PlzA
may act as a matchmaker RNA chaperone aiding in sRNA and target RNA
interactions throughout the enzootic cycle of the spirochete (Fig. 7).