Transport and deamination of amino acids by a gram-positive, monensin-sensitive ruminal bacterium.
01 Jul 1990-Applied and Environmental Microbiology (American Society for Microbiology)-Vol. 56, Iss: 7, pp 2186-2192
TL;DR: Strain F, a recently isolated ruminal bacterium, grew rapidly with glutamate or glutamine as an energy source in the presence but not the absence of Na, and the membrane bioenergetics of strain F appeared to be solely dependent on Na circulation.
Abstract: Strain F, a recently isolated ruminal bacterium, grew rapidly with glutamate or glutamine as an energy source in the presence but not the absence of Na. Monensin, a Na+/H+ antiporter, completely inhibited bacterial growth and significantly reduced ammonia production (85%), but 3,3',4',5-tetrachlorosalicylanide (a protonophore) and valinomycin had little effect on growth or ammonia production. Dicyclohexylcarbodiimide, a H(+)-ATPase, inhibitor had no effect. The kinetics of glutamate and glutamine transport were biphasic, showing unusually high rates at high substrate concentrations. On the basis of low substrate concentrations (less than 100 microM), the Km values for glutamate and glutamine were 4 and 11 microM, respectively. Strain F had separate carriers for glutamate and glutamine which could be driven by a chemical gradient of Na. An artificial delta psi was unable to drive transport even when Na was present. The glutamate carrier had a single binding site for Na with a Km of 21 mM; the glutamine carrier appeared to have more than one binding site, and the Km was 2.8 mM. Neither carrier could use Li instead of Na. Histidine and serine were also rapidly transported by Na-dependent systems, but serine alone did not allow growth even when Na was present. Because exponentially growing cells at pH 6.9 had little delta psi (-3 mV) and a slightly reversed Z delta pH (+17 mV), it appeared that the membrane bioenergetics of strain F were solely dependent on Na circulation.
Citations
More filters
TL;DR: Emerging evidence shows that dietary factors, such as protein, non-digestible carbohydrates, probiotics, synbiotics and phytochemicals, modulate AA utilization by gut microorganisms.
Abstract: Bacteria in the gastrointestinal (GI) tract play an important role in the metabolism of dietary substances in the gut and extraintestinal tissues. Amino acids (AA) should be taken into consideration in the development of new strategies to enhance efficiency of nutrient utilization because they are not only major components in the diet and building blocks for protein but also regulate energy and protein homeostasis in organisms. The diversity of the AA-fermenting bacteria and their metabolic redundancy make them easier to survive and interact with their neighboring species or eukaryotic host during transition along GI tract. The outcomes of the interactions have important impacts on gut health and whole-body homeostasis. The AA-derived molecules produced by intestinal bacteria affect host health by regulating either host immunity and cell function or microbial composition and metabolism. Emerging evidence shows that dietary factors, such as protein, non-digestible carbohydrates, probiotics, synbiotics and phytochemicals, modulate AA utilization by gut microorganisms. Interdisciplinary research involving nutritionists and microbiologists is expected to rapidly expand knowledge about crucial roles for AA in gut ecology and host health.
398 citations
Cites background from "Transport and deamination of amino ..."
...Other bacterial species might lack peptide transport systems and thus could only utilize extracellular AA and ammonia (27-31)....
[...]
...It was found that sodium-dependent transport and, to a lesser extent, facilitated diffusion play important role in AA transport by some of the dominant AAfermenting bacteria (28, 30, 31)....
[...]
TL;DR: Analysis of the bacterial genome sequences shows that many human and animal pathogens encode primary membrane Na+ pumps, Na+-transporting dicarboxylate decar boxylases or Na-translocating NADH:ubiquinone oxidoreductase, and a number of Na-dependent permeases, which indicates that these bacteria can utilize Na+ as a coupling ion instead of or in addition to the H+ cycle.
Abstract: Analysis of the bacterial genome sequences shows that many human and animal pathogens encode primary membrane Na+ pumps, Na+-transporting dicarboxylate decarboxylases or Na+-translocating NADH:ubiquinone oxidoreductase, and a number of Na+-dependent permeases. This indicates that these bacteria can utilize Na+ as a coupling ion instead of or in addition to the H+ cycle. This capability to use a Na+ cycle might be an important virulence factor for such pathogens as Vibrio cholerae, Neisseria meningitidis, Salmonella enterica serovar Typhi, and Yersinia pestis. In Treponema pallidum, Chlamydia trachomatis, and Chlamydia pneumoniae, the Na+ gradient may well be the only energy source for secondary transport. A survey of preliminary genome sequences of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Treponema denticola indicates that these oral pathogens also rely on the Na+ cycle for at least part of their energy metabolism. The possible roles of the Na+ cycling in the energy metabolism and pathogenicity of these organisms are reviewed. The recent discovery of an effective natural antibiotic, korormicin, targeted against the Na+-translocating NADH:ubiquinone oxidoreductase, suggests a potential use of Na+ pumps as drug targets and/or vaccine candidates. The antimicrobial potential of other inhibitors of the Na+ cycle, such as monensin, Li+ and Ag+ ions, and amiloride derivatives, is discussed.
216 citations
Cites background from "Transport and deamination of amino ..."
...An Na -motive, biotin-dependent glutaconyl-CoA decarboxylase and an Na -motive membrane ATPase are apparently operative in this bacterium (24)....
[...]
..., which imports some amino acids in symport with Na ions (24, 25)....
[...]
TL;DR: The sequence data made it clear that strain FT warranted designation as a separate species, and additional strains that are phenotypically similar to strain FT were isolated in this study.
Abstract: In previous studies, gram-positive bacteria which grew rapidly with peptides or an amino acid as the sole energy source were isolated from bovine rumina. Three isolates, strains C, FT (T = type strain), and SR, were considered to be ecologically important since they produced up to 20-fold more ammonia than other ammonia-producing ruminal bacteria. On the basis of phenotypic criteria, the taxonomic position of these new isolates was uncertain. In this study, the 16S rRNA sequences of these isolates and related bacteria were determined to establish the phylogenetic positions of the organisms. The sequences of strains C, FT, and SR and reference strains of Peptostreptococcus anaerobius, Clostridium sticklandii, Clostridium coccoides, Clostridium aminovalericum, Acetomaculum ruminis, Clostridium leptum, Clostridium lituseburense, Clostridium acidiurici, and Clostridium barkeri were determined by using a modified Sanger dideoxy chain termination method. Strain C, a large coccus purported to belong to the genus Peptostreptococcus, was closely related to P. anaerobius, with a level of sequence similarity of 99.6%. Strain SR, a heat-resistant, short, rod-shaped organism, was closely related to C. sticklandii, with a level of sequence similarity of 99.9%. However, strain FT, a heat-resistant, pleomorphic, rod-shaped organism, was only distantly related to some clostridial species and P. anaerobius. On the basis of the sequence data, it was clear that strain FT warranted designation as a separate species. The closest known relative of strain FT was C. coccoides (level of similarity, only 90.6%). Additional strains that are phenotypically similar to strain FT were isolated in this study. On the basis of phenotypic and phylogenetic differences, we believe that strain FT represents a new species of the genus Clostridium, for which we propose the name Clostridium aminophilum.
150 citations
01 Jan 1997
TL;DR: The transfer of energy from the protonmotive force to ATP via a membrane-bound reversible ATPase is a vital link between catabolic and anabolic reactions.
Abstract: The work of biological growth depends on the transfer of energy from catabolic (yielding) to anabolic (consuming) reactions (Figure 6.1). Classically, the two reactions have been depicted to be connected by ATP, in the sense that the energy released by, for example, the glycolytic breakdown of sugars is conserved in the form of ATP, which then provides the energy necessary for the biosynthesis of cell material. It is now clear that most organisms, including anaerobes, can conserve energy, in the form of a transmembrane electrochemical gradient of protons, or protonmotive force (Mitchell, 1961; Thauer et al., 1977; Dawes, 1986). However, the protonmotive force drives few biosynthetic processes directly, and the transfer of energy from the protonmotive force to ATP via a membrane-bound reversible ATPase is a vital link between catabolic and anabolic reactions.
129 citations
TL;DR: It is concluded that the feed additive monensin cannot entirely counteract the wasteful amino acid deamination of obligate amino acid-fermenting ruminal bacteria.
Abstract: Ruminal amino acid degradation is a nutritionally wasteful process that produces excess ruminal ammonia. Monensin inhibited the growth of monensin-sensitive, obligate amino acid-fermenting bacteria and decreased the ruminal ammonia concentrations of cattle. 16S rRNA probes indicated that monensin inhibited the growth of Peptostreptococcus anaerobius and Clostridium sticklandii in the rumen. Clostridium aminophilum was monensin sensitive in vitro, but C. aminophilum persisted in the rumen after monensin was added to the diet. An in vitro culture system was developed to assess the competition of C. aminophilum, P. anaerobius, and C. sticklandii with predominant ruminal bacteria (PRB). PRB were isolated from a 10(8) dilution of ruminal fluid and maintained as a mixed population with a mixture of carbohydrates. PRB did not hybridize with the probes to C. aminophilum, P. anaerobius, or C. sticklandii. PRB deaminated Trypticase in continuous culture, but the addition of C. aminophilum, P. anaerobius, and C. sticklandii caused a more-than-twofold increase in the steady-state concentration of ammonia. C. aminophilum, P. anaerobius, and C. sticklandii accounted for less than 5% of the total 16S rRNA and microbial protein. Monensin eliminated P. anaerobius and C. sticklandii from continuous cultures, but it could not inhibit C. aminophilum. The monensin resistance of C. aminophilum was a growth rate-dependent, inoculum size-independent phenomenon that could not be maintained in batch culture. On the basis of these results, we concluded that the feed additive monensin cannot entirely counteract the wasteful amino acid deamination of obligate amino acid-fermenting ruminal bacteria.
103 citations
Cites background from "Transport and deamination of amino ..."
...aminophilum does not have a large a proton motive force across its cell membrane (7), but it has a monensin-sensitive sodium gradient that is needed for amino acid transport and ATP formation (7)....
[...]
References
More filters
Journal Article•
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
289,852 citations
TL;DR: Combinations of reagents are described for the catalyzed indophenol reaction for the determination of ammonia, which produces a stable blue color, and the procedure is adapted to thedetermination of urea after hydrolysis with urease.
Abstract: Combinations of reagents are described for the catalyzed indophenol reaction for the determination of ammonia, which produces a stable blue color. The procedure is adapted to the determination of urea after hydrolysis with urease.
3,453 citations
"Transport and deamination of amino ..." refers methods in this paper
...Ammonia was assayed by the colorimetric method of Chaney and Marbach (4)....
[...]
TL;DR: A review of the currently valid names of bacteria is conducted with the object of retaining only names for those taxa which were adequately described and cultivable, for which there was a Type, Neotype, or Reference strain available.
Abstract: At the meeting of the Judicial Commission
of the ICSB held in Jerusalem on the 29th
March, 1973 an Ad Hoc Committee was
appointed (Minute 22) to organize a review of
the currently valid names of bacteria with the
object of retaining only names for those taxa
which were adequately described and, if
cultivable, for which there was a Type, Neotype
or Reference strain available; to compile these
names under the title of Approved Lists of
Bacterial Names and to publish the lists in the
International Journal of Systematic Bacteriology,
to become effective on January 1, 1980...
2,458 citations
TL;DR: Article synthese concernant les effets des ionophores, en particulier la monensine, sur l'ecologie, sur le metabolisme microbien, and the physiologie membranaire de la flore microbienne des ruminants.
Abstract: Article synthese concernant les effets des ionophores, en particulier la monensine, sur l'ecologie, sur le metabolisme microbien, et la physiologie membranaire de la flore microbienne des ruminants
551 citations
"Transport and deamination of amino ..." refers background in this paper
...Ionophores have usually been described as ruminal methane inhibitors, but some of the benefit can be ascribed to a decrease in ruminal ammonia (22)....
[...]
TL;DR: Two general types of transport systems have been elucidated in the vesicle system: group translocation systems which catalyze vectorial covalent reactions; and respirationlinked transport systems that catalyze the active transport of a whole range of metabolites against an electrochemical or osmotic gradient.
Abstract: The use of bacterial membrane vesicles as an experimental system for the study of active transport has been discussed. Vesicles are prepared from osmotically sensitized bacteria, and consist of osmotically intact, membranebound sacs without internal structure. They retain litle or no cytoplasm. Under appropriate conditions, these vesicles catalyze the transport of a variety of solutes at rates which are comparable, in many cases, to those of intact cells. Two general types of transport systems have been elucidated in the vesicle system: (i) group translocation systems which catalyze vectorial covalent reactions; and (ii) respirationlinked transport systems that catalyze the active transport of a whole range of metabolites against an electrochemical or osmotic gradient. In E. coli membrane vesicles, the respiration-linked transport systems are coupled primarily to the oxidation of (D)-lactate to pyruvate, catalyzed by a flavin-linked, membrane-bound (D)-lactate dehydrogenase which has been purified to homogeneity. Electrons derived from (D)-lactate or certain artificial electron donors are transferred to oxygen by means of a membrane-bound respiratory chain, and respiration is coupled to active transport within a segment of the respiratory chain between the primary dehydrogenase and cytochrome. b(l). The great majority of the individual membrane vesicles in the population catalyze active transport, and the generation or hydtolysis of ATP is not involved. Under anaerobic conditions, fumarate or nitrate can be utilized in place of oxygen as terminal electron acceptors. With the exception that (D)-lactate is not always the most effective electron donor for active transport, vesicles prepared from a number of other organisms catalyze transport in a similar manner. Fluorescent dansylgalactosides are useful molecular probes of active transport in the vesicle system. These compounds are competitive inhibitors of beta-galactoside transport, but are not transported themselves. Fluorescence studies indicate that the lac carrier protein constitutes approximately 3 to 6 percent of the total membrane protein, and that it is not accessible to the external medium unless the membrane is "energized." Thus, energy is coupled to one of the initial steps in the transport process. Studies with a photoaffinity-labeled galactoside provide independent support for this conclusion. When membrane vesicles prepared from a (D)-lactate dehydrogenase mutant of E. coli are treated with (D)-lactate dehydrogenase, the enzyme binds to the vesicles and they regain the capacity to catalyze (D)-lactate oxidation and (D)-lactate-dependent active transport. The maximal specific transport activity obtained in the reconstituted system is similar in magnitude to that of wildtype vesicles. Titration studies with dansylgalactoside demonstrate that there is at least a seven- to eightfold excess of lac carrier protein relative to (D)-lactate dehydrogenase. Evidence is presented indicating that the enzyme is bound to the inner surface of native membrane vesicles and to the outer surface of reconstituted vesicles, and that the flavin coenzyme moiety is critically involved in binding. Possible mechanisms of respirationlinked active transport are discussed.
282 citations