The uniqueness of subunit α of mycobacterial F-ATP synthases: An evolutionary variant for niche adaptation
Subramanian Manimekalai, Malathy Sony
Date of Issue2017
School of Biological Sciences
The F1F0 -ATP (F-ATP) synthase is essential for growth of Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). In addition to their synthase function most F-ATP synthases possess an ATP-hydrolase activity, which is coupled to proton-pumping activity. However, the mycobacterial enzyme lacks this reverse activity, but the reason for this deficiency is unclear. Here, we report that a Mycobacterium-specific, 36-amino acid long C-terminal domain in the nucleotide-binding subunit α (Mtα) of F-ATP synthase suppresses its ATPase activity and determined the mechanism of suppression. First, we employed vesicles to show that in intact membrane-embedded mycobacterial F-ATP synthases deletion of the C-terminal domain enabled ATPase and proton-pumping activity. We then generated a heterologous F-ATP synthase model system, which demonstrated that transfer of the mycobacterial C-terminal domain to a standard F-ATP synthase α subunit suppresses ATPase activity. Single-molecule rotation assays indicated that the introduction of this Mycobacterium-specific domain decreased the angular velocity of the power-stroke after ATP binding. Solution X-ray scattering data and NMR results revealed the solution shape of Mtα and the 3D structure of the subunit α C-terminal peptide 521PDEHVEALDEDKLAKEAVKV540 of M. tubercolosis (Mtα(521–540)), respectively. Together with cross-linking studies, the solution structural data lead to a model, in which Mtα(521–540) comes in close proximity with subunit γ residues 104–109, whose interaction may influence the rotation of the camshaft-like subunit γ. Finally, we propose that the unique segment Mtα(514–549), which is accessible at the C terminus of mycobacterial subunit α, is a promising drug epitope.
Journal of Biological Chemistry
© 2017 American Society for Biochemistry and Molecular Biology (ASBMB). This paper was published in Journal of Biological Chemistry and is made available as an electronic reprint (preprint) with permission of American Society for Biochemistry and Molecular Biology (ASBMB). The published version is available at: [http://dx.doi.org/10.1074/jbc.M117.784959]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.