Salt-dependent regulation of archaellins in Haloarcula marismortui

Microbiologyopen. 2019 May;8(5):e00718. doi: 10.1002/mbo3.718. Epub 2018 Oct 1.


Microorganisms require a motility structure to move towards optimal growth conditions. The motility structure from archaea, the archaellum, is fundamentally different from its bacterial counterpart, the flagellum, and is assembled in a similar fashion as type IV pili. The archaellum filament consists of thousands of copies of N-terminally processed archaellin proteins. Several archaea, such as the euryarchaeon Haloarcula marismortui, encode multiple archaellins. Two archaellins of H. marismortui display differential stability under various ionic strengths. This suggests that these proteins behave as ecoparalogs and perform the same function under different environmental conditions. Here, we explored this intriguing system to study the differential regulation of these ecoparalogous archaellins by monitoring their transcription, translation, and assembly into filaments. The salt concentration of the growth medium induced differential expression of the two archaellins. In addition, this analysis indicated that archaellation in H. marismortui is majorly regulated on the level of secretion, by a still unknown mechanism. These findings indicate that in archaea, multiple encoded archaellins are not completely redundant, but in fact can display subtle functional differences, which enable cells to cope with varying environmental conditions.

Keywords: archaea; archaeal flagellum; archaellum; ecoparalogs; halophile; motility.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / metabolism*
  • Cell Surface Extensions / metabolism*
  • Culture Media / chemistry
  • Gene Expression Regulation, Archaeal / drug effects*
  • Haloarcula marismortui / drug effects
  • Haloarcula marismortui / growth & development
  • Haloarcula marismortui / metabolism*
  • Macromolecular Substances / metabolism*
  • Protein Biosynthesis
  • Protein Multimerization*
  • Protein Transport
  • Salts / metabolism*
  • Transcription, Genetic


  • Archaeal Proteins
  • Culture Media
  • Macromolecular Substances
  • Salts

Associated data

  • GENBANK/WP_011224081.1
  • GENBANK/WP_011222137.1
  • GENBANK/WP_049938970.1
  • GENBANK/YP_137938.1