Survival of Pseudomonas putida KT2440 in soil and in the rhizosphere of plants under greenhouse and environmental conditions

Molina, Lázaro

doi:10.1016/s0038-0717(99)00156-x

Cited by 176 publications

(141 citation statements)

References 28 publications

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“…Those that have been identified are the Tcp receptor in S. typhimurium, which mediates positive and negative chemotaxis to citrate and phenol, respectively (9), and PA2652 of P. aeruginosa, which mediates chemotaxis to malate but not to any of the remaining TCA cycle intermediates (7). P. putida KT2440, the model organism chosen for this study, has a saprophytic lifestyle, is able to efficiently colonize roots and seeds (44), and was found to use organic acids present in root exudates as the primary carbon source during rhizosphere colonization (45).…”

Section: Discussionmentioning

confidence: 99%

Identification of a Chemoreceptor for Tricarboxylic Acid Cycle Intermediates

Lacal

Alfonso

Liu

et al. 2010

Journal of Biological Chemistry

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We report the identification of McpS as the specific chemoreceptor for 6 tricarboxylic acid (TCA) cycle intermediates and butyrate in Pseudomonas putida. The analysis of the bacterial mutant deficient in mcpS and complementation assays demonstrate that McpS is the only chemoreceptor of TCA cycle intermediates in the strain under study. TCA cycle intermediates are abundantly present in root exudates, and taxis toward these compounds is proposed to facilitate the access to carbon sources. McpS has an unusually large ligand-binding domain (LBD) that is un-annotated in InterPro and is predicted to contain 6 helices. The ligand profile of McpS was determined by isothermal titration calorimetry of purified recombinant LBD (McpS-LBD). McpS recognizes TCA cycle intermediates butdoes not bind very close structural homologues and derivatives like maleate, aspartate, or tricarballylate. This implies that functional similarity of ligands, such as being part of the same pathway, and not structural similarity is the primary element, which has driven the evolution of receptor specificity. The magnitude of chemotactic responses toward these 7 chemoattractants, as determined by qualitative and quantitative chemotaxis assays, differed largely. Ligands that cause a strong chemotactic response (malate, succinate, and fumarate) were found by differential scanning calorimetry to increase significantly the midpoint of protein unfolding (T m ) and unfolding enthalpy (⌬H) of McpS-LBD. Equilibrium sedimentation studies show that malate, the chemoattractant that causes the strongest chemotactic response, stabilizes the dimeric state of McpS-LBD. In this respect clear parallels exist to the Tar receptor and other eukaryotic receptors, which are discussed.

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Section: Discussionmentioning

confidence: 99%

Identification of a Chemoreceptor for Tricarboxylic Acid Cycle Intermediates

Lacal

Alfonso

Liu

et al. 2010

Journal of Biological Chemistry

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“…putida is a non-pathogenic bacterium present in water and soil and able to colonize plant roots and seeds (31)(32)(33). The DOT-T1E strain was isolated for its particularly high resistance to toxic organic solvents (34) and three RND efflux pumps, TtgABC, TtgDEF, and TtgGHI, were found to be essential for this resistance (35).…”

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confidence: 99%

Effector-Repressor Interactions, Binding of a Single Effector Molecule to the Operator-bound TtgR Homodimer Mediates Derepression

Terán¹,

Krell

Ramos

et al. 2006

Journal of Biological Chemistry

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The RND family transporter TtgABC and its cognate repressor TtgR from Pseudomonas putida DOT-T1E were both shown to possess multidrug recognition properties. Structurally unrelated molecules such as chloramphenicol, butyl paraben, 1,3-dihydroxynaphthalene, and several flavonoids are substrates of TtgABC and activate pump expression by binding to the TtgR-operator complex. Isothermal titration calorimetry was employed to determine the thermodynamic parameters for the binding of these molecules to TtgR. Dissociation constants were in the range from 1 to 150 M, the binding stoichiometry was one effector molecule per dimer of TtgR, and the process was driven by favorable enthalpy changes. Although TtgR exhibits a large multidrug binding profile, the plantderived compounds phloretin and quercetin were shown to bind with the highest affinity (K D of around 1 M), in contrast to other effectors (chloramphenicol and aromatic solvents) for which exhibited a more reduced affinity. Structure-function studies of effectors indicate that the presence of aromatic rings as well as hydroxyl groups are determinants for TtgR binding. The binding of TtgR to its operator DNA does not alter the protein effector profile nor the effector binding stoichiometry. Moreover, we demonstrate here for the first time that the binding of a single effector molecule to the DNA-bound TtgR homodimer induces the dissociation of the repressor-operator complex. This provides important insight into the molecular mechanism of effector-mediated derepression.

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“…However, seeds are one of the principal ways of propagation of plant-associated bacteria, constitute a reservoir of plant pathogens, and are the most effective vehicle to introduce plant-beneficial inoculants in the field for agricultural purposes or for rhizoremediation (24,31). Determinants of seed colonization have been studied in Pseudomonas spp.…”

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confidence: 99%

Cell Density-Dependent Gene Contributes to Efficient Seed Colonization by Pseudomonas putida KT2440

Espinosa‐Urgel

Ramos

2004

Appl Environ Microbiol

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We have characterized the expression pattern of a gene, ddcA, involved in initial colonization of corn seeds by Pseudomonas putida KT2440. The ddcA gene codes for a putative membrane polypeptide belonging to a family of conserved proteins of unknown function. Members of this family are widespread among prokaryotes and include the products of a Salmonella enterica serovar Typhimurium gene expressed during invasion of macrophages and psiE, an Escherichia coli phosphate starvation-inducible gene. Although its specific role is undetermined, the presence of ddcA in multicopy restored the seed adhesion capacity of a KT2440 ddcA mutant. Expression of ddcA is growth phase regulated, being maximal at the beginning of stationary phase. It is independent of RpoS, nutrient depletion, or phosphate starvation, and it is not the result of changes in the medium pH during growth. Expression of ddcA is directly dependent on cell density, being also stimulated by the addition of conditioned medium and of seed exudates. This is the first evidence suggesting the existence of a quorum-sensing system in P. putida KT2440. The potential implication of such a signaling process in seed adhesion and colonization by the bacterium is discussed.

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Survival of Pseudomonas putida KT2440 in soil and in the rhizosphere of plants under greenhouse and environmental conditions

Cited by 176 publications

References 28 publications

Identification of a Chemoreceptor for Tricarboxylic Acid Cycle Intermediates

Identification of a Chemoreceptor for Tricarboxylic Acid Cycle Intermediates

Effector-Repressor Interactions, Binding of a Single Effector Molecule to the Operator-bound TtgR Homodimer Mediates Derepression

Cell Density-Dependent Gene Contributes to Efficient Seed Colonization by Pseudomonas putida KT2440

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