Archaeal type IV pilus-like structures--evolutionarily conserved prokaryotic surface organelles.

In both bacteria and Archaea, the biosynthesis of type IV pilus-related structures involves a set of core components, including a prepilin peptidase that specifically processes precursors of pilin-like proteins. Although in silico analyses showed that most sequenced archaeal genomes encode predicted pilins and conserved pilus biosynthesis components, recent in vivo analyses of archaeal pili in genetically tractable crenarchaea and euryarchaea revealed Archaea-specific type IV pilus functions and biosynthesis components. Studies in a variety of archaeal species will reveal which type IV pilus-like structures are common in Archaea and which are limited to certain species within this domain. The insights gleaned from these studies may also elucidate the roles played by these types of structures in adapting to specific environments.