Abstract
YbeX of Escherichia coli, a member of the CorC protein family, is
encoded in the same operon with ribosome-associated proteins YbeY and
YbeZ. Here, we report the involvement of YbeX in ribosomal metabolism.
The ΔybeX cells accumulate distinct 16S rRNA degradation
intermediates in the 30S particles and the 70S ribosomes. E. coli
lacking ybeX has a lengthened lag phase upon outgrowth from the
stationary phase. This growth phenotype is heterogeneous at the
individual cell level and especially prominent under low extracellular
magnesium levels. The ΔybeX strain is sensitive to elevated
growth temperatures and to several ribosome-targeting antibiotics that
have in common the ability to induce the cold shock response in E.
coli. Although generally milder, the phenotypes of the ΔybeX
mutant overlap with those caused by ybeY deletion. A genetic
screen revealed partial compensation of the ΔybeX growth
phenotype by the overexpression of YbeY. These findings indicate an
interconnectedness amongst the ybeZYX operon genes, highlighting
their roles in ribosomal assembly and/or degradation.