A Stromal Pool of TatA Promotes Tat-dependent Protein Transport across the Thylakoid Membrane

Frielingsdorf, Stefan; Jakob, Mario; Klösgen, Ralf Bernd

doi:10.1074/jbc.m806334200

Cited by 27 publications

(22 citation statements)

References 45 publications

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“…Tha4 is somewhat susceptible to release from thylakoids during washing steps (26). Similar to the results with the cpTatC control, biocytin did not react with the TMD (lanes 5 and 6, V13C) or reacted very poorly (lanes 7 and 8, V21C), suggesting that they were buried at different depths.…”

Section: Resultssupporting

confidence: 73%

The Chloroplast Twin Arginine Transport (Tat) Component, Tha4, Undergoes Conformational Changes Leading to Tat Protein Transport

Aldridge

Storm

Cline

et al. 2012

Journal of Biological Chemistry

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Background: Tha4 is the assumed cpTat protein conduit for transporting folded precursors across thylakoid membranes. Results: During assembly into active Tat translocases, the Tha4 amphipathic helix (APH) and adjacent C-tail undergo accessibility changes. Conclusion: Translocase assembly involves more extensive membrane partitioning of Tha4 APH and packing of C-tails into a mesh-like network. Significance: Conformational change of Tha4 within active translocases leads to Tat protein transport.

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Section: Resultssupporting

confidence: 73%

The Chloroplast Twin Arginine Transport (Tat) Component, Tha4, Undergoes Conformational Changes Leading to Tat Protein Transport

Aldridge

Storm

Cline

et al. 2012

Journal of Biological Chemistry

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“…The trends in structure and dynamics in the more native‐like mimetics as compared to micelles/zwitterionic LUVs can thus be expected for TatA also in native membranes. Moreover, the results support a model in which At TatA can adapt its structure to the environment, which may be important for its function and capability of assembling into functional complexes, particularly so since plant TatA has been shown to be present in active form also in the soluble stroma fraction .…”

Section: Discussionsupporting

confidence: 73%

Structure and dynamics of plant TatA in micelles and lipid bilayers studied by solution NMR

Pettersson

Jakob

et al. 2018

The FEBS Journal

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The twin-arginine translocase (Tat) transports folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of plant chloroplasts. In Gram-negative bacteria and chloroplasts, the translocon consists of three subunits, TatA, TatB, and TatC, of which TatA is responsible for the actual membrane translocation of the substrate. Herein we report on the structure, dynamics, and lipid interactions of a fully functional C-terminally truncated 'core TatA' from Arabidopsis thaliana using solution-state NMR. Our results show that TatA consists of a short N-terminal transmembrane helix (TMH), a short connecting linker (hinge) and a long region with propensity to form an amphiphilic helix (APH). The dynamics of TatA were characterized using N relaxation NMR in combination with model-free analysis. The TMH has order parameters characteristic of a well-structured helix, the hinge is somewhat less rigid, while the APH has lower order parameters indicating structural flexibility. The TMH is short with a surprisingly low protection from solvent, and only the first part of the APH is protected to some extent. In order to uncover possible differences in TatA's structure and dynamics in detergent compared to in a lipid bilayer, fast-tumbling bicelles and large unilamellar vesicles were used. Results indicate that the helicity of TatA increases in both the TMH and APH in the presence of lipids, and that the N-terminal part of the TMH is significantly more rigid. The results indicate that plant TatA has a significant structural plasticity and a capability to adapt to local environments.

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“…In this model, an RR-precursor following its binding to the TatBC complex would initiate the customized recruitment of TatA, a process that also requires the proton-motive force (PMF). Whether TatA is recruited only from membrane-integrated TatA protomers or also from a soluble pool of TatA is still an issue33.…”

mentioning

confidence: 99%

Transmembrane insertion of twin-arginine signal peptides is driven by TatC and regulated by TatB

et al. 2012

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The twin-arginine translocation (Tat) pathway of bacteria and plant chloroplasts mediates the transmembrane transport of folded proteins, which harbour signal sequences with a conserved twin-arginine motif. Many Tat translocases comprise the three membrane proteins TatA, TatB and TatC. TatC was previously shown to be involved in recognizing twin-arginine signal peptides. Here we show that beyond recognition, TatC mediates the transmembrane insertion of a twin-arginine signal sequence, thereby translocating the signal sequence cleavage site across the bilayer. In the absence of TatB, this can lead to the removal of the signal sequence even from a translocation-incompetent substrate. Hence interaction of twin-arginine signal peptides with TatB counteracts their premature cleavage uncoupled from translocation. This capacity of TatB is not shared by the homologous TatA protein. Collectively our results suggest that TatC is an insertase for twin-arginine signal peptides and that translocation-proficient signal sequence recognition requires the concerted action of TatC and TatB.

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A Stromal Pool of TatA Promotes Tat-dependent Protein Transport across the Thylakoid Membrane

Cited by 27 publications

References 45 publications

The Chloroplast Twin Arginine Transport (Tat) Component, Tha4, Undergoes Conformational Changes Leading to Tat Protein Transport

The Chloroplast Twin Arginine Transport (Tat) Component, Tha4, Undergoes Conformational Changes Leading to Tat Protein Transport

Structure and dynamics of plant TatA in micelles and lipid bilayers studied by solution NMR

Transmembrane insertion of twin-arginine signal peptides is driven by TatC and regulated by TatB

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