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  • Hydrophobic mismatch is a key factor in protein transport across lipid bilayer membranes via the Tat pathway JOURNAL OF BIOLOGICAL CHEMISTRY Hao, B., Zhou, W., Theg, S. M. 2021; 298 (7): 101991

    Abstract

    The twin-arginine translocation (Tat) pathway transports folded proteins across membranes in bacteria, thylakoids, plant mitochondria, and archaea. In most species, the active Tat machinery consists of three independent subunits: TatA, TatB, and TatC. TatA and TatB possess short transmembrane alpha helices (TMHs), both of which are only 15 residues long in Escherichia coli. Such short TMHs cause a hydrophobic mismatch between Tat subunits and the membrane bilayer, although the functional significance of this mismatch is unclear. Here, we sought to address the functional importance of the hydrophobic mismatch in the Tat transport mechanism in E. coli. We conducted three different assays to evaluate the effect of TMH length mutants on Tat activity and observed that the TMHs of TatA and TatB appear to be evolutionarily tuned to 15 amino acids, with activity dropping off following any modification of this length. Surprisingly, TatA and TatB with as few as 11 residues in their TMHs can still insert into the membrane bilayer, albeit with a decline in membrane integrity. These findings support a model of Tat transport utilizing localized toroidal pores that form when the membrane bilayer is thinned to a critical threshold. In this context, we conclude that the 15-residue length of the TatA and TatB TMHs can be seen as a compromise between the need for some hydrophobic mismatch to allow the membrane to reversibly reach the threshold thinness required for toroidal pore formation and the permanently destabilizing effect of placing even shorter helices into these energy-transducing membranes.

    View details for DOI 10.1016/j.jbc.2022.101991

    View details for Web of Science ID 000829544300002

    View details for PubMedID 35490783

    View details for PubMedCentralID PMC9207671

  • Honeycomb-Spherical Co3O4-TiO2 Hybrid Materials for Enhanced Lithium Storage ELECTROCHIMICA ACTA Li, Y., Shang, K., Zhou, W., Tan, L., Pan, X., Liao, M., Lei, J., Zhao, L. 2016; 222: 1642-1649