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Microbial desulfonation pathways for natural and pharmacologically relevant C 3-sulfonates

Microbial desulfonation pathways for natural and pharmacologically relevant C 3-sulfonates


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MAYER, Jutta, 2011. Microbial desulfonation pathways for natural and pharmacologically relevant C 3-sulfonates

@phdthesis{Mayer2011Micro-12399, title={Microbial desulfonation pathways for natural and pharmacologically relevant C 3-sulfonates}, year={2011}, author={Mayer, Jutta}, address={Konstanz}, school={Universität Konstanz} }

Mayer, Jutta Homotaurine (3-aminopropanesulfonate), cysteate (2-amino-3-sulfopropanoate), 3-sulfolactate (2-hydroxy-3-sulfopropanoate), 2,3-dihydroxypropane-1-sulfonate (DHPS) and 3-sulfopropanoate are widespread, naturally occuring C3-sulfonates. To our<br /><br />nowledge, organosulfonates are degraded solely by microorganisms, which are capable of cleaving the chemically stable C-sulfonate bond. The elucidation of degradative pathways in aerobic bacteria utilizing the above mentioned C3-sulfonates as sole<br /><br />sources of carbon and energy or, if possible, as sole sources of nitrogen, was the aim of this study.<br />Isolates utilizing homotaurine as sole carbon and energy source or as sole nitrogen source were easily obtained. The assimilation of homotaurine-nitrogen was studied with an isolate identified as Burkholderia sp. strain N-APS2. The organism excreted<br /><br />3-sulfopropanoate during growth with homotaurine-nitrogen, and expressed an inducible homotaurine:2-oxoglutarate aminotransferase. The same phenomena were observed during work with the genomesequenced Cupriavidus necator H16, which<br /><br />revealed the involvement of genes and enzymes from both GABA and sulfonate metabolism: GABA permease (GabP) for homotaurine-uptake, GABA transaminase (GabT) for its deamination to 3-sulfopropanal, and succinatesemialdehyde<br /><br />dehydrogenase (GabD1) for the oxidation of the latter to 3-sulfopropanoate, whose excretion was attributed to the sulfite/sulfonate exporter TauE.<br />The assimilation of cysteate-nitrogen by C. necator H16 was also found to involve an initial transamination reaction. A cysteate:2-oxoglutarate aminotransferase (Coa), which might be an aspartate aminotransferase (Aoa) according to its substrate<br /><br />pectrum, yielded 3-sulfopyruvate.Traces of the latter were found in the growth medium, together with putative 3-sulfolactate, whose formation from 3-sulfopyruvate was attributed to the activity of a putative (S)-sulfolactate dehydrogenase (SlcC). Again,<br /><br />TauE might be responsible for organosulfonate export; the identity of a transporter for cysteate uptake, however, is still unknown.<br />The utilization of 3-sulfolactate as a source of carbon and energy in the genome-sequenced Roseovarius nubinhibens ISM was found to involve a largely inducible, bifurcated pathway, which allowed the desulfonation via sulfoacetaldehyde<br /><br />cetyltransferase (Xsc) and (R)-cysteate sulfo-lyase (CuyA). A putative tripartite tricarboxylate transporter (TTT; SlcHFG) was responsible for uptake of sulfolactate, which was oxidized to 3-sulfopyruvate by a membranebound sulfolactate dehydrogenase<br /><br />(SlcD). 3-Sulfopyruvate, the point of bifurcation, was transaminated to cysteate in one branch, or decarboxylated to sulfoacetaldehyde in the other branch. The decarboxylating enzyme, 3-sulfopyruvate decarboxylase (ComDE) is known from the<br /><br />coenzyme M biosynthetic pathway.<br />In this study, 3-Sulfolactate was discovered as a central intermediate in the degradation of several C3-sulfonates, such as DHPS, homotaurine and 3-sulfopropanoate. In the dissimilation of racemic DHPS, three inducible DHPS dehydrogenases<br /><br />(HpsNOP) acted as a racemase (HpsOP) and oxidized (R)-DHPS to (R)-sulfolacate (HpsN). These enzymes were studied in R. nubinhibens ISM, which degraded the resulting sulfolactate via the bifurcated pathway described above, and in Cupriavidus<br /><br />pinatubonensis JMP134, which used (R)-sulfolactate sulfolyase (SuyAB) for desulfonation. Transporter candidates were available in both organisms: a putative tripartite ATP-independent periplasmic (TRAP) transporter in the marine R. nubinhibens, and<br /><br />a major facilitator superfamily (MFS) transporter in the terrestrial C. pinatubonensis.<br />The utilization of homotaurine as a source of carbon and energy was studied in R. nubinhibens, whose substrate spectrum was found to include not only 3-sulfolacate and DHPS, but also homotaurine and 3-sulfopropanoate. As in the nitrogen-<br /><br />ssimilatory pathway, transamination and oxidation were observed, but a different transporter (HtaABCD) and aminotransferase (HtaE) became apparent. Two more novel enzymes were found for the further degradation of 3-sulfopropanoate: 3-<br /><br />ulfopropanoate dehydrogenase (SpuBCDA), which yielded 3-sulfopropenoate, and 3-sulfopropenoate dehydratase (SpuIJ), whose predicted product was 3-sulfolactate. Activities of Xsc and CuyA confirmed the presence of the bifurcated pathway for 3-<br /><br />sulfolactate degradation (see above).<br />Work on the dissimilation of homotaurine revealed nine organisms which encoded the spu-gene cluster for 3-sulfopropanoate degradation. Rhodobacter sphaeroides 2.4.1, which grew with 3-sulfopropanoate, was presumed to degrade it via Xsc; there<br /><br />were, however, no gene candidates for the sulfopyruvate decarboxylase ComDE. Instead, we found a gene encoding for a putative novel 3-sulfopyruvate decarboxylase (SpuE), which is currently under investigation. 2011-04-07T10:43:38Z 2011 Mayer, Jutta eng Microbial desulfonation pathways for natural and pharmacologically relevant C 3-sulfonates deposit-license 2011-04-07T10:43:38Z

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

Dissertation Jutta Mayer.pdf 86

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