Motility in Archaea- the Archaellum
Archaea use a unique structure for swimming motility which is not hoomologous to bacterial flagella, but instead resembles type IV pili. But in contrast to type IV pili, motion is not achieved by elongation and disassembly of the filament, but by rotation.
The smallest known archaellum operon is present in Sulfolobus acidocaldarius. Therefore we used the S. acidoalcarius archaellum as a model system to understand which role the different proteins play during assembly and rotation of the archaellum. To that end we use biochemical, genetic and structural approaches.
So far we have reported the structures of FlaI, FlaH and FlaF (follow the links to the publications). These structural analyses were done in a successful collaboration with the lab of John Tainer .
The image shows the graphical abstract of our recent paper about FlaH in Molecular Microbiology (Chaudhury et al, 2016). Although FlaH is not an active ATPase, nucleotide binding is essential for its interaction with FlaH and therefore archaellum assembly.
In our latest we show that FlaG forms a filament and interacts via FlaF with the S-layer. The interaction of FlaF with the S-layer is essential for torque-generation by the archaellum to allow rotation of the filament.
Papers:
Tsai CL, Tripp P, Sivabalasarma S, Zhang C, Rodriguez-Franco M, Wipfler RL, Chaudhury P, Banerjee A, Beeby M, Whitaker RJ, Tainer JA, Albers SV. (2020) The structure of the periplasmic FlaG-FlaF complex and its essential role for archaellar swimming motility.
Nat Microbiol. 2020 Jan;5(1):216-225. doi: 10.1038/s41564-019-0622-3.
Chaudhury P, Neiner T, D'Imprima E, Banerjee A, Reindl S, Ghosh A, Arvai AS, Mills DJ, van der Does C, Tainer JA, Vonck J, Albers SV. (2016) The nucleotide-dependent interaction of FlaH and FlaI is essential for assembly and function of the archaellum motor.
Mol Microbiol. 2016 Feb;99(4):674-85. doi: 10.1111/mmi.13260.
Banerjee A, Tsai CL, Chaudhury P, Tripp P, Arvai AS, Ishida JP, Tainer JA, Albers SV. (2015) FlaF Is a β-Sandwich Protein that Anchors the Archaellum in the Archaeal Cell Envelope by Binding the S-Layer Protein.
Structure. 2015 May 5;23(5):863-872. doi: 10.1016/j.str.2015.03.001.
Reindl S, Ghosh A, Williams GJ, Lassak K, Neiner T, Henche AL, Albers SV, Tainer JA. (2013) Insights into FlaI functions in archaeal motor assembly and motility from structures, conformations, and genetics.
Mol Cell. 2013 Mar 28;49(6):1069-82. doi: 10.1016/j.molcel.2013.01.014. Epub 2013 Feb 14.