Homology Model of the Na+/Proline Transporter PutP of Escherichia coli and Its Functional Implications

Olkhova, Elena; Raba, Michael; Bracher, Susanne; Hilger, Daniel; Jung, Heinrich

doi:10.1016/j.jmb.2010.11.045

Cited by 24 publications

(65 citation statements)

References 41 publications

(78 reference statements)

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“…The PutP protein (491 amino acids) is predicted to function as a high-affinity proline importer that belongs to the sodium solute symporter family, whose members couple the import of the substrate with the inflow of Na ϩ ions (48). The B. subtilis PutP transporter exhibits 54% amino acid sequence identity to the wellstudied proline importer PutP from E. coli (48).…”

Section: Resultsmentioning

confidence: 99%

“…The B. subtilis PutP transporter exhibits 54% amino acid sequence identity to the wellstudied proline importer PutP from E. coli (48). The E. coli PutP protein is predicted to comprise 13 membrane-spanning segments, and those residues known to be involved in L (40,48).…”

Section: Resultsmentioning

confidence: 99%

“…PutP is a high-affinity proline importer and a member of the sodium solute symporter (SSS) (TC2A.21) family, transporters that harness electrochemical Na ϩ gradients to couple the flow of Na ϩ ions with the transport of solutes across biological membranes (48). The PutA protein is a trifunctional membraneassociated enzyme comprising both PRODH and P5CDH domains ( Fig.…”

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confidence: 99%

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Proline Utilization by Bacillus subtilis: Uptake and Catabolism

et al. 2012

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L-Proline can be used by Bacillus subtilis as a sole source of carbon or nitrogen. We traced L-proline utilization genetically to the putBCP (ycgMNO) locus. The putBCP gene cluster encodes a high-affinity proline transporter (PutP) and two enzymes, the proline dehydrogenase PutB and the ⌬ 1 -pyrroline-5-carboxylate dehydrogenase PutC, which jointly catabolize L-proline to L-glutamate. Northern blotting, primer extension, and putB-treA reporter gene fusion analysis showed that the putBCP locus is transcribed as an L-proline-inducible operon. Its expression was mediated by a SigA-type promoter and was dependent on the proline-responsive PutR activator protein. Induction of putBCP expression was triggered by the presence of submillimolar concentrations of L-proline in the growth medium. However, the very large quantities of L-proline (up to several hundred millimolar) synthesized by B. subtilis as a stress protectant against high osmolarity did not induce putBCP transcription. Induction of putBCP transcription by external L-proline was not dependent on L-proline uptake via the substrate-inducible PutP or the osmotically inducible OpuE transporter. It was also not dependent on the chemoreceptor protein McpC required for chemotaxis toward L-proline. Our findings imply that B. subtilis can distinguish externally supplied L-proline from internal L-proline pools generated through de novo synthesis. The molecular basis of this regulatory phenomenon is not understood. However, it provides the B. subtilis cell with a means to avoid a futile cycle of de novo L-proline synthesis and consumption by not triggering the expression of the putBCP L-proline catabolic genes in response to the osmoadaptive production of the compatible solute L-proline.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Proline Utilization by Bacillus subtilis: Uptake and Catabolism

et al. 2012

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“…Although the PutP and OpuE proline transporters are closely related to each other with respect to both their amino acid sequences (10,16) and the mechanism by which they import their common substrate in cotransport with sodium ions (31,33,34,37), they have clearly different cellular functions in B. subtilis. Their primary physiological roles can be discerned from the distinct transcriptional profile of their structural genes (10,16,23,28,29) and the different abilities of the PutP and OpuE proteins to withstand the inhibiting effects of high salinity on their transport activity (10).…”

Section: Discussionmentioning

confidence: 99%

“…The PutP and OpuE proteins are closely related to each other (61% amino acid sequence identity) and to the biochemically well-studied PutP proline permease from Escherichia coli and Salmonella enterica serovar Typhimurium (31,(33)(34)(35)(36)(37). Both the B. subtilis PutP and the OpuE L-proline transporters possess a high affinity for their substrate, with K m values being in the low M range, and they exhibit a substantial transport capacity (10).…”

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confidence: 99%

The γ-Aminobutyrate Permease GabP Serves as the Third Proline Transporter of Bacillus subtilis

et al. 2014

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bPutP and OpuE serve as proline transporters when this imino acid is used by Bacillus subtilis as a nutrient or as an osmostress protectant, respectively. The simultaneous inactivation of the PutP and OpuE systems still allows the utilization of proline as a nutrient. This growth phenotype pointed to the presence of a third proline transport system in B. subtilis. We took advantage of the sensitivity of a putP opuE double mutant to the toxic proline analog 3,4-dehydro-DL-proline (DHP) to identify this additional proline uptake system. DHP-resistant mutants were selected and found to be defective in the use of proline as a nutrient. Whole-genome resequencing of one of these strains provided the lead that the inactivation of the ␥-aminobutyrate (GABA) transporter GabP was responsible for these phenotypes. DNA sequencing of the gabP gene in 14 additionally analyzed DHPresistant strains confirmed this finding. Consistently, each of the DHP-resistant mutants was defective not only in the use of proline as a nutrient but also in the use of GABA as a nitrogen source. The same phenotype resulted from the targeted deletion of the gabP gene in a putP opuE mutant strain. Hence, the GabP carrier not only serves as an uptake system for GABA but also functions as the third proline transporter of B. subtilis. Uptake studies with radiolabeled GABA and proline confirmed this conclusion and provided information on the kinetic parameters of the GabP carrier for both of these substrates.

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Management of Osmotic Stress by Bacillus Subtilis : Genetics and Physiology

Hoffmann

Bremer

2016

Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria

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Homology Model of the Na+/Proline Transporter PutP of Escherichia coli and Its Functional Implications

Cited by 24 publications

References 41 publications

Proline Utilization by Bacillus subtilis: Uptake and Catabolism

Proline Utilization by Bacillus subtilis: Uptake and Catabolism

The γ-Aminobutyrate Permease GabP Serves as the Third Proline Transporter of Bacillus subtilis

Management of Osmotic Stress by Bacillus Subtilis : Genetics and Physiology

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