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  Alternating-access mechanism in conformationally asymmetric trimers of the betaine transporter BetP

Perez, C., Koshy, C., Yildiz, Ö., & Ziegler, C. (2012). Alternating-access mechanism in conformationally asymmetric trimers of the betaine transporter BetP. Nature, 490, 126-130. doi:10.1038/nature11403.

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 Creators:
Perez, Camilo1, Author           
Koshy, Caroline1, Author           
Yildiz, Özkan1, Author           
Ziegler, Christine1, Author           
Affiliations:
1Department of Structural Biology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068291              

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 Abstract: Betaine and Na(+) symport has been extensively studied in the osmotically regulated transporter BetP from Corynebacterium glutamicum, a member of the betaine/choline/carnitine transporter family, which shares the conserved LeuT-like fold of two inverted structural repeats. BetP adjusts its transport activity by sensing the cytoplasmic K(+) concentration as a measure for hyperosmotic stress via the osmosensing carboxy-terminal domain. BetP needs to be in a trimeric state for communication between individual protomers through several intratrimeric interaction sites. Recently, crystal structures of inward-facing BetP trimers have contributed to our understanding of activity regulation on a molecular level. Here we report new crystal structures, which reveal two conformationally asymmetric BetP trimers, capturing among them three distinct transport states. We observe a total of four new conformations at once: an outward-open apo and an outward-occluded apo state, and two closed transition states--one in complex with betaine and one substrate-free. On the basis of these new structures, we identified local and global conformational changes in BetP that underlie the molecular transport mechanism, which partially resemble structural changes observed in other sodium-coupled LeuT-like fold transporters, but show differences we attribute to the osmolytic nature of betaine, the exclusive substrate specificity and the regulatory properties of BetP.

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Language(s): eng - English
 Dates: 2012-09-022012-10-04
 Publication Status: Published in print
 Pages: 5
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: eDoc: 625165
DOI: 10.1038/nature11403
 Degree: -

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Title: Nature
  Abbreviation : Nature
Source Genre: Journal
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Publ. Info: London : Nature Publishing Group
Pages: - Volume / Issue: 490 Sequence Number: - Start / End Page: 126 - 130 Identifier: ISSN: 0028-0836
CoNE: https://pure.mpg.de/cone/journals/resource/954925427238