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Microbiology. 2017 May 23. doi: 10.1099/mic.0.000464. [Epub ahead of print]

Phylogenetic distribution of the euryarchaeal archaellum regulator EarA and complementation of a Methanococcus maripaludis ∆earA mutant with heterologous earA homologues.

Author information

1
1​Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
2
2​Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.

Abstract

Archaella are the swimming organelles in the Archaea. Recently, the first archaellum regulator in the Euryarchaeota, EarAMma, was identified in Methanococcus maripaludis, one of the model organisms used for archaellum studies. EarAMma binds to 6 bp consensus sequences upstream of the fla promoter to activate the transcription of the fla operon, which encodes most of the proteins required for archaella synthesis. In this study, synteny analysis showed that earA homologues are widely distributed in the phylum of Euryarchaeota, with the notable exception of extreme halophiles. We classified Euryarchaeota species containing earA homologues into five classes based on the genomic location of the earA genes relative to fla and chemotaxis operons. EarA homologues from Methanococcus vannielii, Methanothermococcus thermolithotrophicus and Methanocaldococcus jannaschii successfully complemented the function of EarAMma in a ΔearAMma mutant, demonstrated by the restoration of FlaB2 expression in Western blot analysis and the appearance of archaella on the cell surface in complemented cells. Furthermore, the 6 bp consensus sequence was also found in the fla promoter region in these methanogens, indicating that the EarA homologues ly use a similar mechanism to activate transcription of the fla operons in their own hosts. Attempts to demonstrate complementation of the function of EarAMma in a ΔearAMma mutant by the EarA homologue of Pyrococcus furiosus were unsuccessful, despite the presence of a copy of the 6 bp consensus EarA-binding sequence upstream of the fla promoter in the P. furiosus genome.

PMID:
28535845
DOI:
10.1099/mic.0.000464

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