The Relationship between Methionine Uptake and Demethiolation in a Methionine-utilizing Mutant of Pseudomonas fluorescens UK1

Laakso, Simo

doi:10.1099/00221287-95-2-391

Cited by 15 publications

(3 citation statements)

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“…DMS formation was observed in both molybdateand BES-inhibited samples, suggesting that organisms other than sulfate reducers and methanogens can form DMS (20,31,41). However, sulfate reducers may play at least a partial role, since DMS production was partially inhibited by MoO42-.…”

Section: Discussionmentioning

confidence: 96%

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Kiene

Visscher

1987

Appl Environ Microbiol

152

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Anoxic salt marsh sediments were amended with DL-methionine and dimethylsulfoniopropionate (DMSP). Microbial metabolism of methionine yielded methane thiol (MSH) as the major volatile organosulfur product, with the formation of lesser amounts of dimethylsulfide (DMS). Biological transformation of DMSP resulted in the rapid release of DMS and only small amounts of MSH. Experiments with microbial inhibitors indicated that production of MSH from methionine was carried out by procaryotic organisms, probably sulfate-reducing bacteria. Methane-producing bacteria did not metabolize methionine. The involvement of specific groups of organisms in DMSP hydrolysis could not be determined with the inhibitors used, because DMSP was hydrolyzed in all samples except those which were autoclaved. Unamended sediment slurries, prepared from Spartina alterniflora sediments, contained significant (1 to 10 R,M) concentrations of DMS. Endogenous methylated sulfur compounds and those produced from added methionine and DMSP were consumed by sediment microbes. Both sulfate-reducing and methane-producing bacteria were involved in DMS and MSH consumption. Methanogenesis was stimulated by the volatile organosulfur compounds released from methionine and DMSP. However, apparent competition for these compounds exists between methanogens and sulfate reducers. At low (1 ,uM) concentrations of methionine, the terminal S-methyl group was metabolized almost exclusively to CO2 and only small amounts of CH4. At higher (>100 ,IM) concentrations of methionine, the proportion of the methyl-sulfur group converted to CH4 increased. The results of this study demonstrate that methionine and DMSP are potential precursors of methylated sulfur compounds in anoxic sediments and that the microbial community is capable of metabolizing volatile methylated sulfur compounds.

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Section: Discussionmentioning

confidence: 96%

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Kiene

Visscher

1987

Appl Environ Microbiol

152

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“…B. linens CNRZ 918, like Pseudomonas fluorescens UK1 (20,23), has only one L-methionine transport system with low affinity (Km = 55 ,uM). In contrast, the existence of two systems with high and low affinities has been shown in E. coli (14, 17) and S. typhimurium (1, 2).…”

Section: Discussionmentioning

confidence: 99%

Na ⁺ -Stimulated Transport of l -Methionine in Brevibacterium linens CNRZ 918

Ferchichi

Hemme

Nardi

1987

Appl Environ Microbiol

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The transport of L-methionine by the gram-positive species Brevibacterium linens CNRZ 918 is described. The one transport system (Km = 55 ,uM) found is constitutive for L-methionine, stereospecific, and pH and temperature dependent. Entry of L-methionine into cells is controlled by the internal methionine pool. Competition studies indicate that L-methionine and aL-aminobutyric acid share a common carrier for their transport. Neither methionine derivatives substituted on the amino or carboxyl groups nor D-methionine was an inhibitor, whereas powerful inhibition was shown by L-cysteine, s-methyl-L-cysteine, DL-selenomethionine and DL-homocysteine. Sodium plays important and varied roles in L-methionine transport by B. linens CNRZ 918: (i) it stimulates transport without affecting the Km, (ii) it increases the specific activity (on a biomass basis) of the L-methionine transport system when present with methionine in the medium, suggesting a coinduction mechanism. L-Methionine transport requires an exogenous energy source, which may be succinic, lactic, acetic, or pyruvic acid but not glucose or sucrose. The fact that L-methionine transport was stimulated by potassium arsenate and to a lesser extent by potassium fluoride suggests that high-energy phosphorylated intermediates are not involved in the process. Monensin eliminates stimulation by sodium. Gramicidin and carbonyl cyanide-m-chlorophenylhydrazone act in the presence or absence of Na+. N-Ethylmaleimide, p-chloromercurobenzoate, valinomycin, sodium azide, and potassium cyanide have no or only a partial inhibitory effect. These results tend to indicate that the proton motive force reinforced by the Na+ gradient is involved in the mechanism of energy coupling of L-methionine transport by B. linens CNRZ 918. Thus, this transport is partially similar to the well-described systems in gram-negative bacteria, except for the role of sodium, which is very effective in B. linens, a species adapted to the high sodium levels of its niche.

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“…fluorescens UKI has an inducible methionine transport system with a Km of 25 j.LM (Mantsala et al, 1974) which has broad specificity for amino acids (Laakso, 1976). Membrane vesicles prepared from methionine-grown P. fluorescens UKI exhibit methionine uptake in an energydependent manner, suggesting that the transport system is a carriermediated transport system (Mantsala et al, 1974).…”

Section: Methioninementioning

confidence: 99%

Pseudomonas

1998

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The Relationship between Methionine Uptake and Demethiolation in a Methionine-utilizing Mutant of Pseudomonas fluorescens UK1

Cited by 15 publications

References 1 publication

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Na ⁺ -Stimulated Transport of l -Methionine in Brevibacterium linens CNRZ 918

Pseudomonas

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The Relationship between Methionine Uptake and Demethiolation in a Methionine-utilizing Mutant of Pseudomonas fluorescens UK1

Cited by 15 publications

References 1 publication

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Production and Fate of Methylated Sulfur Compounds from Methionine and Dimethylsulfoniopropionate in Anoxic Salt Marsh Sediments

Na + -Stimulated Transport of l -Methionine in Brevibacterium linens CNRZ 918

Pseudomonas

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Na ⁺ -Stimulated Transport of l -Methionine in Brevibacterium linens CNRZ 918