Papers in the Biological Sciences
Date of this Version
Biochem Soc Trans. 2009 February ; 37(Pt 1): 123–126.
TA (toxin–antitoxin) loci are ubiquitous in prokaryotic microorganisms, including archaea, yet
their physiological function is largely unknown. For example, preliminary reports have suggested
that TA loci are microbial stress-response elements, although it was recently shown that knocking
out all known chromosomally located TA loci in Escherichia coli did not have an impact on
survival under certain types of stress. The hyperthermophilic crenarchaeon Sulfolobus solfataricus
encodes at least 26 vapBC (where vap is virulence-associated protein) family TA loci in its
genome. VapCs are PIN (PilT N-terminus) domain proteins with putative ribonuclease activity,
while VapBs are proteolytically labile proteins, which purportedly function to silence VapCs when
associated as a cognate pair. Global transcriptional analysis of S. solfataricus heat-shock-response
dynamics (temperature shift from 80 to 90°C) revealed that several vapBC genes were triggered
by the thermal shift, suggesting a role in heat-shock-response. Indeed, knocking out a specific
vapBC locus in S. solfataricus substantially changed the transcriptome and, in one case, rendered
the crenarchaeon heat-shock-labile. These findings indicate that more work needs to be done to
determine the role of VapBCs in S. solfataricus and other thermophilic archaea, especially with
respect to post-transcriptional regulation.
Copyright 2009 by the Authors. Journal compilation (c) 2009 Biochemical Society.