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. Author manuscript; available in PMC: 2014 Mar 28.
Published in final edited form as: Mol Cell. 2013 Feb 14;49(6):1069–1082. doi: 10.1016/j.molcel.2013.01.014

Figure 1. FlaI ATPase activity is essential for archaellum formation.

Figure 1

(A) EM images of the Sulfolobus cell surface (from left to right): The background is a hyper-archaellated strain (ΔaapF) that lacks pili. Deletion of the flaI gene results in no surface archaella. FlaI function is restored by introducing wild-type flaI or the Walker A mutant. The Walker B mutant strain is incapable of complementation, indicating the need of enzymatic ATPase activity for archaellum assembly.

(B) Wild-type FlaI, FlaIK268A Walker A and FlaIE336A Walker B mutants are expressed in the ΔaapFΔflaI mutant strain. Expression was detected by western blot, with the archaellin protein (FlaB) used as an endogenous control.

(C) Motility assays showing the ability of wild-type and FlaI variants to complement the motility phenotype in the ΔaapFΔflaI strain. From left to right: Swimming behavior of the in trans complemented ΔaapFΔflaI with wild-type FlaI, FlaI Walker AK268A mutant and FlaI Walker B mutant. See also Figure S1, Movie S1 and S2).