کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1945332 | 1537148 | 2007 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Structural characterization of the pore forming protein TatAd of the twin-arginine translocase in membranes by solid-state 15N-NMR Structural characterization of the pore forming protein TatAd of the twin-arginine translocase in membranes by solid-state 15N-NMR](/preview/png/1945332.png)
The transmembrane protein TatA is the pore forming unit of the twin-arginine translocase (Tat), which has the unique ability of transporting folded proteins across the cell membrane. This ATP-independent protein export pathway is a recently discovered alternative to the general secretory (Sec) system of bacteria. To obtain insight in the translocation mechanism, the structure and alignment in the membrane of the well-folded segments 2–45 of TatAd from Bacillus subtilis was studied here. Using solid-state NMR in bicelles containing anionic lipids, the topology and orientation of TatAd was determined in an environment mimicking the bacterial membrane. A wheel-like pattern, characteristic for a tilted transmembrane helix, was observed in 15N chemical shift /15N–1H dipolar coupling correlation NMR spectra. Analysis of this PISA wheel revealed a 14–16 residue long N-terminal membrane-spanning helix which is tilted by 17° with respect to the membrane normal. In addition, comparison of uniformly and selectively 15N-labeled TatA2–45 samples allowed determination of the helix polarity angle.
Journal: Biochimica et Biophysica Acta (BBA) - Biomembranes - Volume 1768, Issue 12, December 2007, Pages 3071–3079