ClpP-dependent and -independent activities encoded by the polycistronic clpK-encoding locus contribute to heat shock survival in Klebsiella pneumoniae

The family of Clp ATPases plays an important role in bacterial physiology. Here we characterize the genetic locus encompassing a newly described plasmid-encoded ClpK protein protecting Klebsiella pneumoniae cells during heat shock. We demonstrate that the clpK gene is located in a polycistronic operon and that the variable downstream gene content correlates with heat-resistant phenotypes of different isolates. ClpK is encoded by a multifunctional transcriptional unit characterized by both ClpP-dependent and -independent activities. Notably, our data show that ClpP is indispensible for thermoprotection exerted by ClpK alone, suggesting that ClpK is a new member of the family of ClpP-interacting Clp ATPases.