IMR Press / FBL / Volume 17 / Issue 2 / DOI: 10.2741/3955

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Review
The Na⁺/L-proline transporter PutP
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1 LMU Munich, Biocentre, Microbiology, Grosshaderner Strasse 2-4, Martinsried, D-82152, Germany
Academic Editor:Guoyao Wu
Front. Biosci. (Landmark Ed) 2012, 17(2), 745–759; https://doi.org/10.2741/3955
Published: 1 January 2012
(This article belongs to the Special Issue Amino acids in nutrition, health, and disease)
Abstract

The Na⁺/L-proline transporter PutP is a member of the Na⁺/solute symporter family (TC 2A.21, SLC5), which contains several hundred proteins of pro- and eukaryotic origin. Within the family, the capability of L-proline uptake is restricted to proteins of prokaryotes. PutP contributes to the use of L-proline as a nutrient. In addition, the transporter may supply cells with compatible solute during adaptation to osmotic stress. Based on these and other functions, PutP is of significance for various bacteria-host interactions including the virulence of human pathogens. A homology model of Escherichia coli PutP was generated based on the crystal structure of the Vibrio parahaemolyticus Na+/galactose symporter. According to the model, PutP has a core structure of five plus five transmembrane domains forming an inverted repeat similar as originally revealed by the crystal structure of the Na+/leucine transporter LeuT. The homology model is experimentally verified by Cys cross-linking and site-directed spin labeling in combination with electron paramagnetic resonance spectroscopy. The putative sites of Na⁺ and L-proline binding are described, and a putative transport mechanism is discussed.


Keywords
PutP
Proline
Transport
Sodium/Solute Symport
Review
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