Study of Escherichia coli TatA

FERNANDA RODRIGUEZ; JASON SCHNELL; BEN C. BERKS

Munich

Congreso; SFB Meeting: Molecular Machines in Protein Folding and Transport; 2012

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-fareast-language:EN-GB;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> In the Tat pathway, proteins are translocated fully folded across the cell membrane. The Tat pathway is found in bacteria, archaea and plant chloroplasts, and is required for important bacterial cellular processes including respiratory and photosynthetic energy metabolism, cell division, cell motility, quorum sensing, heavy metal resistance, iron acquisition, and biofilm formation. In E. coli, Tat consists of three components: TatA, TatB, and TatC. Experimental evidence suggests that a TatBC complex binds to the signal peptide of the substrate protein. This binding event triggers the assembly of TatA with the TatBC-substrate complex, and the substrate protein is then translocated probably via TatA. TatA is an 89-residue protein comprising an N-terminal transmembrane helix, followed by an amphipathic helix, and an unstructured and hydrophilic cytoplasmic tail. TatA is currently considered to form tetramers that act as building blocks for the higher-order oligomers that mediate transport. The higher-order polymerisation of TatA is dynamic and thought to be biased by substrate-bound TatBC. In this work we report the results of structural studies by NMR spectroscopy performed on E. coli TatA aimed at unveiling its molecular mechanism of action.