Pipecolic acid is an osmoprotectant for Escherichia coli taken up by the general osmoporters ProU and ProP

Gouesbet, Gwenola; Jebbar, Mohamed; Talibart, Roland; Bernard, Théophile; Blanco, Carlos

doi:10.1099/13500872-140-9-2415

Cited by 68 publications

(74 citation statements)

References 36 publications

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“…We showed that at least two uptake systems exist in E. chrysanthemi, both involved in the uptake of the four osmoprotectants glycine betaine, proline, ectoine, and pipecolic acid. This feature is identical to the system in E. coli, in which the osmoporters ProP and ProU are involved in the uptake of all known osmoprotectants (5,11,13,19,28,29). ProU, the high-affinity binding-protein-dependent transport system, is encoded by the osmoinducible proU operon (12,14,27), whereas the proP gene, encoding the low-affinity transport system, has a constitutive expression which is enhanced by osmotic shock and amino acid limitation (15,20,28).…”

Section: Discussionmentioning

confidence: 86%

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

et al. 1996

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Growth of Erwinia chrysanthemi in media of elevated osmolarity can be achieved by the uptake and accumulation of various osmoprotectants. This study deals with the cloning and sequencing of the ousA geneencoded osmoprotectant uptake system A from E. chrysanthemi 3937. OusA belongs to the superfamily of solute ion cotransporters. This osmotically inducible system allows the uptake of glycine betaine, proline, ectoine, and pipecolic acid and presents strong similarities in nucleotide sequence and protein function with the proline/ betaine porter of Escherichia coli encoded by proP. The control of ousA expression is clearly different from that of proP. It is induced by osmotic strength and repressed by osmoprotectants. Its expression in E. coli is controlled by H-NS and is rpoS dependent in the exponential phase but unaffected by the stationary phase.Microbial pathogens encounter extremely diverse environments both inside and outside their hosts. In response to these adverse conditions, they undergo striking adaptations in order to survive and retain virulence. The growth of Erwinia chrysanthemi, which is involved in a systemic soft rot disease on a variety of higher plants, is influenced by desiccation (18, 21). We have recently analyzed the influence of osmotic strength on E. chrysanthemi growth and pathogenicity in the absence and presence of osmoprotectants (10). The consequences for pathogenicity were estimated by the effect of osmotic pressure on transcription of pel genes and pectate lyase activity. The transcription of the pelE gene, encoding the major extracellular pectate lyase enzyme, is induced in medium of high osmolarity, whereas the cellular growth rate was reduced. Osmoprotectants such as glycine betaine, proline, ectoine, and pipecolic acid were shown to be accumulated in the cells through an osmoinducible mechanism and stimulated growth. However, pelE transcription was reduced to basal levels.Although uptake and accumulation of osmoprotectants have been observed in many bacteria, transporter structural genes have been characterized in only a few microorganisms. Considering the regulation of their transcription, a knowledge of which is essential to understanding osmoregulation, only the proP and proU operons of Escherichia coli and Salmonella typhimurium have been analyzed in depth (6-8, 13, 14, 20, 27, 28, 31, 32). The identification of structural domains involved in osmosensing and substrate binding could be improved by comparison of ProP and ProU with other osmoprotectant transporters in other bacteria. In this report, we characterize one of the osmoprotectant transporters of E. chrysanthemi, analogous to ProP of E. coli. MATERIALS AND METHODSBacterial strains, plasmids, media, and growth conditions. The E. coli and E. chrysanthemi strains and plasmids used are described in Table 1. Cells were grown in LB or M63 glucose (0.2%) medium (33). E. chrysanthemi cells were usually incubated at 30ЊC, and E. coli cells were incubated at 37ЊC. The osmoprotectants choline, glycine betaine, proline, ectoin...

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Section: Discussionmentioning

confidence: 86%

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

et al. 1996

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“…Since E. coli can tolerate up to 900 mM NaCl on minimal medium (MM63) only in the presence of external osmoprotectants (15) ism was strongly supported in the surroundings of KB2-1 and KB2 due to ectoine leakage into the medium (Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

New Type of Osmoregulated Solute Transporter Identified in Halophilic Members of theBacteriaDomain: TRAP Transporter TeaABC Mediates Uptake of Ectoine and Hydroxyectoine inHalomonas elongataDSM 2581^T

2002

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The halophilic bacterium Halomonas elongata synthesizes as its main compatible solute the aspartate derivative ectoine. We constructed a deletion mutant of H. elongata, KB1, defective in ectoine synthesis and tolerating elevated salt concentrations only in the presence of external compatible solutes. The dependency of KB1 on solute uptake for growth in high-salt medium was exploited to select insertion mutants unable to accumulate external solutes via osmoregulated transporters. One insertion mutant out of 7,200 failed to accumulate the osmoprotectants ectoine and hydroxyectoine. Genetic analysis of the insertion site proved that the mutation affected an open reading frame (ORF) of 1,281 bp (teaC). The nucleotide sequence upstream of teaC was determined, and two further ORFs of 603 bp (teaB) and 1,023 bp (teaA) were identified. Deletion of teaA and teaB proved that all three genes are mandatory for ectoine uptake. Sequence comparison showed significant identity of TeaA, TeaB, and TeaC to the transport proteins of the recently identified tripartite ATP-independent periplasmic transporter family (TRAP-T). The affinity of the cells for ectoines was determined (K s ‫؍‬ 21.7 M), suggesting that the transporter TeaABC exhibits high affinity for ectoines. An elevation of the external osmolarity resulted in a strong increase in ectoine uptake via TeaABC, demonstrating that this transporter is osmoregulated. Deletion of teaC and teaBC in the wild-type strain led to mutants which excreted significant amounts of ectoine into the medium when cultivated at high salt concentrations. Therefore, the physiological role of TeaABC may be primarily to recover ectoine leaking through the cytoplasmic membrane.Halophilic organisms living in saline environments such as salt lakes, coastal lagoons, and man-made salterns are challenged by two stress factors, the high inorganic ion concentration and the low water potential. A nonadapted organism exposed to such an environment must cope with its cytoplasmic water having a higher water potential than the water of the surrounding environment. Water always flows from a high to a low potential until the potential gradient is abolished. Thus, the cytoplasm, which is surrounded by a membrane freely permeable to water, will lose its free cytoplasmic water, resulting in cell shrinkage (4). The loss of water will cause cessation of growth, possibly due to molecular crowding, and thus reduced diffusion rates of proteins and metabolites.Halophilic prokaryotes have developed two principal mechanisms to lower the potential of cytoplasmic water, avoiding the loss of water from the cell and achieving a cytoplasm of osmotic strength similar to that of the surrounding medium. These two mechanisms, which allow osmotic adaptation, are the salt-in-cytoplasm mechanism and the organic-osmolyte mechanism.The salt-in-cytoplasm mechanism is considered the typical archaeal strategy of osmoadaptation (e.g., halobacteria). However, members of the Bacteria domain such as Salinibacter ruber and a specialized group of g...

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“…In this study, it was found that carnitine can function as an osmoprotectant for E. (Gouesbet et al 1994) and several betaines such as r-butyrobetaine, alanine betaine, proline betaine and pipecolate betaine (Haardt etal. 1995;Randall etul.…”

Section: Discussionmentioning

confidence: 99%

A possible role of ProP, ProU and CaiT in osmoprotection of Escherichia coli by carnitine

Verheul

Wouters

Rombouts

et al. 1998

Journal of Applied Microbiology

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A VERHEUL. J A WOUTERS. F.M. ROMBOUTS AND T. ABEE. 1998. Exogenously provided carnitine (P-h!-droxy-r.-r-.V-trimethyl aminobutyrate) was found to stimulate aerobic growth of enterohaemorrhagic Escherzchiu mli 0 1 57:H7 in a medium of inhibitory osmotic strength. Its osmoprotective ability is comparable with that of betaine. As carnitine is an important compound in mammalian tissues, it is suggested that it might play a role in the growth of the pathogen on low water activity (a,) meat products. Using specific uptake mutants of E. i d i K-12, it was established that, under osmotic stress, carnitine accumulates in the cytoplasm following import through the Prop and ProU transport systems. Betaine and carnitine also protect E. coli cells while growing anaerobically at inhibitory osmolarity. Under these conditions, an E. coli K-12 strain with lesions in both prop and pro U accumulates low levels of I,-carnitine but fails to accumulate betaine when these compounds are supplied in the external medium. This is probably a result of uptake of J,-carnitine by the secondary transporter CaiT. T h e 1uiT gene forms part of the ruiTABCDE operon which encodes the carnitine pathway, and is transcribed during anaerobic growth in the presence of carnitine.However, further experiments revealed that the carnitine pathway, including CaiT, does not play a significant role in osmoregulation of E. mli during anaerobiosis. Together, the results indicate that Prop and ProU are the sole transport systems involved in carnitine influx, both in aerobically and anaerobically osmotically stressed E. coli cells.

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Pipecolic acid is an osmoprotectant for Escherichia coli taken up by the general osmoporters ProU and ProP

Cited by 68 publications

References 36 publications

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

New Type of Osmoregulated Solute Transporter Identified in Halophilic Members of theBacteriaDomain: TRAP Transporter TeaABC Mediates Uptake of Ectoine and Hydroxyectoine inHalomonas elongataDSM 2581^T

A possible role of ProP, ProU and CaiT in osmoprotection of Escherichia coli by carnitine

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Pipecolic acid is an osmoprotectant for Escherichia coli taken up by the general osmoporters ProU and ProP

Cited by 68 publications

References 36 publications

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

Characterization of the Erwinia chrysanthemi osmoprotectant transporter gene ousA

New Type of Osmoregulated Solute Transporter Identified in Halophilic Members of theBacteriaDomain: TRAP Transporter TeaABC Mediates Uptake of Ectoine and Hydroxyectoine inHalomonas elongataDSM 2581T

A possible role of ProP, ProU and CaiT in osmoprotection of Escherichia coli by carnitine

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New Type of Osmoregulated Solute Transporter Identified in Halophilic Members of theBacteriaDomain: TRAP Transporter TeaABC Mediates Uptake of Ectoine and Hydroxyectoine inHalomonas elongataDSM 2581^T