Poly(3-mercaptopropionate):  A Nonbiodegradable Biopolymer?

Kim, Do Young; Lütke‐Eversloh, Tina; Elbanna, Кhaled; Thakor, Nitish V.; Steinbüchel, Alexander

doi:10.1021/bm049334x

Cited by 45 publications

(44 citation statements)

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“…However, the biotechnological significance of these organic sulphur compounds (OSCs) is their application in studies for the improvement of polythioester (PTE) production (Lütke-Eversloh & Steinbüchel, 2003). PTEs are microbially synthesized, non-biodegradable polymers containing sulphur in the thioester linkages of the backbone (Kim et al, 2005;Lütke-Eversloh et al, 2002a). They accumulate as hydrophobic inclusions in the cytoplasm of bacterial cells in a manner similar to polyhydroxyalkanoic acids (PHAs) (Lütke-Eversloh & Steinbüchel, 2004).…”

Section: Introductionmentioning

confidence: 99%

Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

et al. 2010

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Application of the non-toxic 3,3′-thiodipropionic acid (TDP) and 3,3′-dithiodipropionic acid (DTDP) as precursors for the microbial production of polythioesters (PTEs), a class of biologically persistent biopolymers containing sulphur in the backbone, was successfully established previously. However, synthesis of PTEs containing 4-mercaptobutyrate (4MB) as building blocks could not be achieved. The very harmful 4MB is not used as a PTE precursor or as the carbon source for growth by any known strain. As a promising alternative, the harmless oxidized disulfide of two molecules of 4MB, 4,4′-dithiodibutyric acid (DTDB), was employed for enrichments of bacterial strains capable of biodegradation. Investigation of novel precursor substrates for PTEs and comparison of respective strains growing on TDP, DTDP and DTDB as sole carbon source was accomplished. A broad variety of bacteria capable of using one of these organic sulphur compounds were isolated and compared. TDP and DTDP were degraded by several strains belonging to different genera, whereas all DTDB-utilizing strains were affiliated to the species Rhodococcus erythropolis. Transposon mutagenesis of R. erythropolis strain MI2 and screening of 7500 resulting mutants yielded three mutants exhibiting impaired growth on DTDB. Physiological studies revealed production of volatile hydrogen sulphide and accumulation of significant amounts of 4MB, 4-oxo-4-sulphanylbutanoic acid and succinic acid in the culture supernatants. Based on this knowledge, a putative pathway for degradation of DTDB was proposed: DTDB could be cleaved into two molecules of 4MB, followed by an oxidation yielding 4-oxo-4-sulphanylbutanoic acid. A putative desulphydrase probably catalyses the abstraction of sulphur, thereby generating succinic acid and hydrogen sulphide.

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Section: Introductionmentioning

confidence: 99%

Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

et al. 2010

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“…Microbially synthesized PTEs are nonbiodegradable polymers containing sulfur in their backbones (19,20). PTEs are accumulated in the cytoplasm of some bacterial cells, forming hydrophobic inclusions, such as the well-known polyhydroxyalkanoates (PHAs) (21,22).…”

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Biodegradation of the Organic Disulfide 4,4′-Dithiodibutyric Acid by Rhodococcus spp

Khairy

Wübbeler

Steinbüchel

2015

Appl Environ Microbiol

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c Four Rhodococcus spp. exhibited the ability to use 4,4=-dithiodibutyric acid (DTDB) as a sole carbon source for growth. The most important step for the production of a novel polythioester (PTE) using DTDB as a precursor substrate is the initial cleavage of DTDB. Thus, identification of the enzyme responsible for this step was mandatory. Because Rhodococcus erythropolis strain MI2 serves as a model organism for elucidation of the biodegradation of DTDB, it was used to identify the genes encoding the enzymes involved in DTDB utilization. To identify these genes, transposon mutagenesis of R. erythropolis MI2 was carried out using transposon pTNR-TA. Among 3,261 mutants screened, 8 showed no growth with DTDB as the sole carbon source. In five mutants, the insertion locus was mapped either within a gene coding for a polysaccharide deacetyltransferase, a putative ATPase, or an acetyl coenzyme A transferase, 1 bp upstream of a gene coding for a putative methylase, or 176 bp downstream of a gene coding for a putative kinase. In another mutant, the insertion was localized between genes encoding a putative transcriptional regulator of the TetR family (noxR) and an NADH:flavin oxidoreductase (nox). Moreover, in two other mutants, the insertion loci were mapped within a gene encoding a hypothetical protein in the vicinity of noxR and nox. The interruption mutant generated, R. erythropolis MI2 nox⍀tsr, was unable to grow with DTDB as the sole carbon source. Subsequently, nox was overexpressed and purified, and its activity with DTDB was measured. The specific enzyme activity of Nox amounted to 1.2 ؎ 0.15 U/mg. Therefore, we propose that Nox is responsible for the initial cleavage of DTDB into 2 molecules of 4-mercaptobutyric acid (4MB).T he genus Rhodococcus has attracted great interest in recent years due to the ability of many of its species to degrade and transform a wide range of xenobiotic substances (1). Rhodococci are described as aerobic, Gram-positive, mycolate-containing actinomycetes with high genomic GϩC contents. They have a diverse set of genetic and catabolic features, because of the presence of large linear plasmids in addition to their large chromosomes (2). The number of publications and patents involving Rhodococcus spp. has increased significantly in recent years (3).Rhodococcus spp. have been isolated from a variety of sources. They are ubiquitous in soils contaminated with crude oil and/or other xenobiotic compounds. The ability of Rhodococcus species to degrade substituted hydrocarbons and other chemicals allows them to play a role in the natural degradation and bioremediation of such compounds (4). Many Rhodococcus species are characterized by broad metabolic diversity and an array of unique enzymatic capabilities; therefore, they are also of interest for pharmaceutical, environmental, chemical, and energy studies. They play a significant role in the process of desulfurization of fossil fuels (5) and in the industrial production of acrylamide (6). Strains of Rhodococcus erythropolis have been identi...

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“…Thus, E. coli cells harboring a plasmid containing the BPEC genes synthesized poly(3-mercaptopropionate) [poly(3MP)], poly (3-mercaptobutyrate) [poly(3MB)], or poly(3-mercaptovalerate) [poly(3MV)] (21). Additionally, it was discovered that poly(3MP) is practically nonbiodegradable (8,14). R. eutropha H16 synthesizes copolymers of 3HB and 3MP, 3-mercaptobutyrate (3MB) or 3-mercaptovalerate (3MV), when cells are cultivated in the presence of various thiochemicals (20,23).…”

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Impact of Multiple β-Ketothiolase Deletion Mutations in Ralstonia eutropha H16 on the Composition of 3-Mercaptopropionic Acid-Containing Copolymers

Lindenkamp

Peplinski

Володина

et al. 2010

Appl Environ Microbiol

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␤-Ketothiolases catalyze the first step of poly(3-hydroxybutyrate) [poly(3HB)] synthesis in bacteria by condensing two molecules of acetyl coenzyme A (acetyl-CoA) to acetoacetyl-CoA. Analyses of the genome sequence of Ralstonia eutropha H16 revealed 15 isoenzymes of PhaA in this bacterium. In this study, we generated knockout mutants of various phaA homologues to investigate their role in and contributions to poly(3HB) metabolism and to suppress biosynthesis of 3HB-CoA for obtaining enhanced molar 3-mercaptopriopionate (3MP) contents in poly(3HB-co-3MP) copolymers when cells were grown on gluconate plus 3-mercaptopropionate or 3,3-dithiodipropionate. In silico sequence analysis of PhaA homologues, transcriptome data, and other aspects recommended the homologues phaA, bktB, H16_A1713/H16_B1771, H16_A1528, H16_B1369, H16_B0381, and H16_A0170 for further analysis. Single-and multiple-deletion mutants were generated to investigate the influence of these ␤-ketothiolases on growth and polymer accumulation. The deletion of single genes resulted in no significant differences from the wild type regarding growth and polymer accumulation during cultivation on gluconate or gluconate plus 3MP. Deletion of phaA plus bktB (H16⌬2 mutant) resulted in approximately 30% less polymer accumulation than in the wild type. Deletion of H16_A1713/H16_B1771, H16_A1528, H16_B0381, and H16_B1369 in addition to phaA and bktB gave no differences in comparison to the H16⌬2 mutant. In contrast, deletion of H16_A0170 additionally to phaA and bktB yielded a mutant which accumulated about 30% poly(3HB) (wt/wt of the cell dry weight [CDW]). Although we were not able to suppress poly(3HB) biosynthesis completely, the copolymer compositions could be altered significantly with a lowered percentage ratio of 3HB constituents (from 85 to 52 mol%) and an increased percentage ratio of 3MP constituents (from 15 to 48 mol%), respectively. In this study, we demonstrated that PhaA, BktB, and H16_A0170 are majorly involved in poly(3HB) synthesis in R. eutropha H16. A fourth ␤-ketothiolase or a combination of several of the other ␤-ketothiolases contributed to a maximum of only 30% (wt/wt of CDW) of the remaining (co)polymer.Polyhydroxyalkanoates (PHAs) are naturally occurring polyoxoesters that are synthesized and accumulated as cytoplasmic inclusions by diverse bacteria. Poly(3-hydroxybutyrate) [poly(3HB)] was detected in 1926 by Maurice Lemoigne as an intracellular compound of Bacillus megaterium (16). Generally the accumulation of PHAs proceeds under unbalanced cultivation conditions when a carbon source is available in excess and if another macroelement like nitrogen, phosphorus, or oxygen is limiting growth at the same time (36,44). Ralstonia eutropha strain H16, a Gramnegative facultative chemolithoautotrophic hydrogen-oxidizing bacterium, accumulates poly(3HB) as insoluble granules as a storage compound for carbon and energy in the cytoplasm. The genome of R. eutropha H16 harbors the PHA operon, which comprises three genes encoding a ␤-ketothiolase (phaA...

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Poly(3-mercaptopropionate): A Nonbiodegradable Biopolymer?

Cited by 45 publications

References 28 publications

Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

Biodegradation of the Organic Disulfide 4,4′-Dithiodibutyric Acid by Rhodococcus spp

Impact of Multiple β-Ketothiolase Deletion Mutations in Ralstonia eutropha H16 on the Composition of 3-Mercaptopropionic Acid-Containing Copolymers

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