Rhodobacter sphaeroides Uses a Reductive Route via Propionyl Coenzyme A To Assimilate 3-Hydroxypropionate

Schneider, Kathrin; Asao, Marie; Carter, Michael S.; Alber, Birgit E.

doi:10.1128/jb.05959-11

Cited by 28 publications

(50 citation statements)

References 45 publications

(48 reference statements)

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“…Kinetic regulation of metabolic processes is well known, but here we see evidence that it plays an unexpected role in large-scale biogeochemical 1 processes mediated by metabolically streamlined cells. 2 The model presented in Fig. S8 captures the observations we report, and provides an 3 explanation for why cells might simultaneously express two pathways that compete for a single 4 substrate.…”

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confidence: 94%

“…Also reported in nearly all 1 Pelagibacterales are genes encoding methyl group oxidation pathways (Fig. S1), which 2 produce energy from DMSP demethylation and are essential to the demethylation pathway 3 because they perform the function of regenerating the methyl-group-accepting cofactor 4 tetrahydrofolate (THF) 15,20 . Pelagibacterales strains also contain homologs of cystathionine-5 gamma-synthetase (cys-γ-synth), predicted to catalyze the conversion of MeSH to methionine 21 , 6 and thus necessary for growth using MeSH as a sole sulfur source.…”

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confidence: 99%

“…The predicted homologs for both dddA and dddC are found in all Pelagibacterales strains. yhdH is a homolog of acuI that recently was implicated in reductive 3-HP metabolism in Rhodobacter sphaeroides and R. pomeroyi, and was proposed as part of a novel pathway that converts acrylate to propionyl-CoA via acrylyl-CoA in those organisms 2,3 . This gene has homologs in all Pelagibacterales strains except HIMB59.…”

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The abundant marine bacterium Pelagibacter simultaneously catabolizes dimethylsulfoniopropionate to the gases dimethyl sulfide and methanethiol

et al. 2016

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Marine phytoplankton produce ~109 tons of dimethylsulfoniopropionate (DMSP) per year1,2, an estimated 10% of which is catabolized by bacteria through the DMSP cleavage pathway to the climatically active gas dimethyl sulfide (DMS)3,4. SAR11 Alphaproteobacteria (order Pelagibacterales), the most abundant chemoorganotrophic bacteria in the oceans, have been shown to assimilate DMSP into biomass, thereby supplying this cell’s unusual requirement for reduced sulfur5,6. Here we report that Pelagibacter HTCC1062 produces the gas methanethiol (MeSH) and that simultaneously a second DMSP catabolic pathway, mediated by a cupin-like DMSP lyase, DddK, shunts as much as 59% of DMSP uptake to DMS production. We propose a model in which the allocation of DMSP between these pathways is kinetically controlled to release increasing amounts of DMS as the supply of DMSP exceeds cellular sulfur demands for biosynthesis

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The abundant marine bacterium Pelagibacter simultaneously catabolizes dimethylsulfoniopropionate to the gases dimethyl sulfide and methanethiol

et al. 2016

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“…After the addition of glass beads (0.1 mm in diameter), the cell solution was treated in a tissue lyser (Retsch, Haan, Germany) for 10 min at 30 Hz. Cell debris and glass beads were removed by centrifugation at 4°C (58). Protein concentrations were determined using the bicinchoninic acid (BCA) assay (Thermo Scientific [63]) according to the manufacturer's instructions and bovine serum albumin (BSA) as a standard.…”

Section: Chemicals [mentioning

confidence: 99%

Oxalyl-Coenzyme A Reduction to Glyoxylate Is the Preferred Route of Oxalate Assimilation in Methylobacterium extorquens AM1

2012

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Oxalate catabolism is conducted by phylogenetically diverse organisms, including Methylobacterium extorquens AM1. Here, we investigate the central metabolism of this alphaproteobacterium during growth on oxalate by using proteomics, mutant characterization, and 13 C-labeling experiments. Our results confirm that energy conservation proceeds as previously described for M. extorquens AM1 and other characterized oxalotrophic bacteria via oxalyl-coenzyme A (oxalyl-CoA) decarboxylase and formyl-CoA transferase and subsequent oxidation to carbon dioxide via formate dehydrogenase. However, in contrast to other oxalate-degrading organisms, the assimilation of this carbon compound in M. extorquens AM1 occurs via the operation of a variant of the serine cycle as follows: oxalyl-CoA reduction to glyoxylate and conversion to glycine and its condensation with methylene-tetrahydrofolate derived from formate, resulting in the formation of C3 units. The recently discovered ethylmalonyl-CoA pathway operates during growth on oxalate but is nevertheless dispensable, indicating that oxalyl-CoA reductase is sufficient to provide the glyoxylate required for biosynthesis. Analysis of an oxalyl-CoA synthetase- and oxalyl-CoA-reductase-deficient double mutant revealed an alternative, although less efficient, strategy for oxalate assimilation via one-carbon intermediates. The alternative process consists of formate assimilation via the tetrahydrofolate pathway to fuel the serine cycle, and the ethylmalonyl-CoA pathway is used for glyoxylate regeneration. Our results support the notion that M. extorquens AM1 has a plastic central metabolism featuring multiple assimilation routes for C1 and C2 substrates, which may contribute to the rapid adaptation of this organism to new substrates and the eventual coconsumption of substrates under environmental conditions.

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“…the gene (RSP_1434) encoding a member of the medium-chain dehydrogenase/reductase (MDR) superfamily was involved in this reductive conversion as shown by mutant analysis (14). Accordingly, we speculated that RSP_1434 might encode an NADPHdependent acrylyl-CoA reductase.…”

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Acrylyl-Coenzyme A Reductase, an Enzyme Involved in the Assimilation of 3-Hydroxypropionate by Rhodobacter sphaeroides

Asao

Alber

2013

J Bacteriol

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The anoxygenic phototroph Rhodobacter sphaeroides uses 3-hydroxypropionate as a sole carbon source for growth. Previously, we showed that the gene (RSP_1434) known as acuI, which encodes a protein of the medium-chain dehydrogenase/reductase (MDR) superfamily, was involved in 3-hydroxypropionate assimilation via the reductive conversion to propionyl-coenzyme A (CoA). Based on these results, we speculated that acuI encoded acrylyl-CoA reductase. In this work, we characterize the in vitro enzyme activity of purified, recombinant AcuI using a coupled spectrophotometric assay. AcuI from R. sphaeroides catalyzes the NADPH-dependent acrylyl-CoA reduction to produce propionyl-CoA. Two other members of the MDR012 family within the MDR superfamily, the products of SPO_1914 from Ruegeria pomeroyi and yhdH from Escherichia coli, were shown to also be part of this new class of NADPH-dependent acrylyl-CoA reductases. The activities of the three enzymes were characterized by an extremely low K m for acrylyl-CoA (<3 M) and turnover numbers of 45 to 80 s ؊1 . These homodimeric enzymes were highly specific for NADPH (K m ‫؍‬ 18 to 33 M), with catalytic efficiencies of more than 10-fold higher for NADPH than for NADH. The introduction of codon-optimized SPO_1914 or yhdH into a ⌬acuI::kan mutant of R. sphaeroides on a plasmid complemented 3-hydroxypropionate-dependent growth. However, in their native hosts, SPO_1914 and yhdH are believed to function in the metabolism of substrates other than 3-hydroxypropionate, where acrylyl-CoA is an intermediate. Complementation of the ⌬acuI::kan mutant phenotype by crotonyl-CoA carboxylase/reductase from R. sphaeroides was attributed to the fact that the enzyme also uses acrylyl-CoA as a substrate.

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Rhodobacter sphaeroides Uses a Reductive Route via Propionyl Coenzyme A To Assimilate 3-Hydroxypropionate

Cited by 28 publications

References 45 publications

The abundant marine bacterium Pelagibacter simultaneously catabolizes dimethylsulfoniopropionate to the gases dimethyl sulfide and methanethiol

The abundant marine bacterium Pelagibacter simultaneously catabolizes dimethylsulfoniopropionate to the gases dimethyl sulfide and methanethiol

Oxalyl-Coenzyme A Reduction to Glyoxylate Is the Preferred Route of Oxalate Assimilation in Methylobacterium extorquens AM1

Acrylyl-Coenzyme A Reductase, an Enzyme Involved in the Assimilation of 3-Hydroxypropionate by Rhodobacter sphaeroides

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