2mi2 | pdb_00002mi2
Solution structure of the E. coli TatB protein in DPC micelles
Structural highlights
FunctionA0A0D8VEJ4_ECOLX Part of the twin-arginine translocation (Tat) system that transports large folded proteins containing a characteristic twin-arginine motif in their signal peptide across membranes. Together with TatC, TatB is part of a receptor directly interacting with Tat signal peptides. TatB may form an oligomeric binding site that transiently accommodates folded Tat precursor proteins before their translocation.[HAMAP-Rule:MF_00237] Publication Abstract from PubMedThe twin-arginine protein transport (Tat) system translocates fully folded proteins across lipid membranes. In Escherichia coli, the Tat system comprises three essential components: TatA, TatB and TatC. The protein translocation process is proposed to initiate by signal peptide recognition and substrate binding to the TatBC complex. Upon formation of the TatBC-substrate protein complex, the TatA subunits are recruited and form the protein translocation pore. Experimental evidences suggest that TatB forms a tight complex with TatC at 1:1 molar ratio and the TatBC complex contains multiple copies of both proteins. Cross-linking experiments demonstrate that TatB functions in tetrameric units and interacts with both TatC and substrate proteins. However, structural information of the TatB protein is still lacking, and its functional mechanism remains elusive. Herein, we report the solution structure of TatB in DPC micelles determined by Nuclear Magnetic Resonance (NMR) spectroscopy. Overall, the structure shows an extended 'L-shape' conformation comprising four helices: a transmembrane helix (TMH) alpha1, an amphipathic helix (APH) alpha2, and two solvent exposed helices alpha3 and alpha4. The packing of TMH and APH is relatively rigid, whereas helices alpha3 and alpha4 display notably higher mobility. The observed floppiness of helices alpha3 and alpha4 allows TatB to sample a large conformational space, thus providing high structural plasticity to interact with substrate proteins of different sizes and shapes. Solution structure of the TatB component of the twin-arginine translocation system.,Zhang Y, Wang L, Hu Y, Jin C Biochim Biophys Acta. 2014 Mar 31;1838(7):1881-1888. doi:, 10.1016/j.bbamem.2014.03.015. PMID:24699374[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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