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Mol Microbiol. 2016 Oct;102(1):54-70. doi: 10.1111/mmi.13444. Epub 2016 Jul 11.

Identification of the first transcriptional activator of an archaellum operon in a euryarchaeon.

Author information

1
Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
2
Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Guelph, Ontario, N1G 3W4, Canada.
3
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
4
Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada. jarrellk@queensu.ca.

Abstract

The archaellum is the swimming organelle of the third domain, the Archaea. In the euryarchaeon Methanococcus maripaludis, genes involved in archaella formation, including the three archaellins flaB1, flaB2 and flaB3, are mainly located in the fla operon. Previous studies have shown that transcription of fla genes and expression of Fla proteins are regulated under different growth conditions. In this study, we identify MMP1718 as the first transcriptional activator that directly regulates the fla operon in M. maripaludis. Mutants carrying an in-frame deletion in mmp1718 did not express FlaB2 detected by western blotting. Quantitative reverse transcription PCR analysis of purified RNA from the Δmmp1718 mutant showed that transcription of flaB2 was negligible compared to wildtype cells. In addition, no archaella were observed on the cell surface of the Δmmp1718 mutant. FlaB2 expression and archaellation were restored when the Δmmp1718 mutant was complemented with mmp1718 in trans. Electrophoretic motility shift assay and isothermal titration calorimetry results demonstrated the specific binding of purified MMP1718 to DNA fragments upstream of the fla promoter. Four 6 bp consensus sequences were found immediately upstream of the fla promoter and are considered the putative MMP1718-binding sites. Herein, we designate MMP1718 as EarA, the first euryarchaeal archaellum regulator.

PMID:
27314758
DOI:
10.1111/mmi.13444
[Indexed for MEDLINE]
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