Journal of Plant Biology

, Volume 62, Issue 2, pp 129–136 | Cite as

Structural Analysis of Tha4, a Twin-arginine Translocase Protein Localized in Plant Thylakoid Membranes

  • Bao van Nguyen
  • Dong Wook Lee
  • Sangmin Lee
  • Inhwan HwangEmail author
  • Gang-Won CheongEmail author
Original Article


The chloroplast has a complex structure with multiple internal thylakoid membranes surrounding internal lumenal compartments. Chloroplast proteins are localized to these suborganellar locations via different protein targeting mechanisms. In this study, we investigated the three-dimensional (3D) structure of Tha4, an essential component of the twinarginine translocation (Tat) system of thylakoid membranes that mediates protein targeting to the lumen. Full-length Tha4 fused with green fluorescent protein (GFP) localized to thylakoid membranes with a discrete punctate staining pattern when expressed transiently in protoplasts. The transit peptidedeleted mature form of Tha4 was expressed in Escherichia coli, yielding multiple high molecular weight complexes in vitro. These complexes adopt ring-shaped structures of varying sizes, and long filamentous structures were also evident. Electron microscopy and image processing analyses revealed a roughly triangular ring-shaped structure, with one end of the complex open, and the other closed, based on the electron density map. The height of the cylindrical pore is ~47 Å, comparable to the thickness of a typical lipid bilayer.


Chloroplast Electron microscopy Tat transporter Tha4 Thylakoid membrane 


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Copyright information

© Korean Society of Plant Biologists 2019

Authors and Affiliations

  1. 1.Divisiot of Life ScienceGyeongsang National UniversityJinjuKorea
  2. 2.Division of Integrative Biosciences and BiotechnologyPohang University of Science and TechnologyPohangKorea
  3. 3.BioApplications Inc., Pohang Techno Park ComplexNam-gu PohangKorea
  4. 4.Department of Life SciencesPohang University of Science and TechnologyPohangKorea

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