ena-STUDY-MPI-MM-11-03-2018-14:01:46:519-349
Transcriptomic and Proteomic Insight into the Mechanism of Cyclooctasulfur- versus Thiosulfate-Oxidation by the Chemolithoautotroph Sulfurimonas denitrificans
Chemoautotrophic bacteria belonging to the genus Sulfurimonas in the class Campylobacteria (formerly classified as Epsilonproteobacteria) play a key role in the sulfur cycle in a variety of oxygen-deficient or –limited and sulfide-rich marine and terrestrial environments. Previously, they were identified as key players in the turnover of zero-valence sulfur, a central intermediate in the marine sulfur cycle, and S. denitrificans was further shown to be able to oxidize cyclooctasulfur. However, at present the mechanism involved in the activation and metabolism of cyclooctasulfur is not known. To this end, we assessed the transcriptome and proteome of S. denitrificans grown with either thiosulfate or cyclooctasulfur as the electron donor. While the overall profiles under the two growth conditions were rather similar, distinct differences were observed that could be attributed to the utilization of cyclooctasulfur. This included a higher abundance of expressed genes and proteins related to attachment in the presence of cyclooctasulfur and the differential expression of the sulfur-oxidation multienzyme complex (SOX). S. denitrificans uses the SOX system for the oxidation of reduced sulfur compounds, including two copies of the sulfur-binding SoxYZ proteins, encoded in two gene clusters: soxABXYZ1 and soxCDYZ2. While the proteins of both operons of the SOX system were detected in the presence of thiosulfate, only proteins of the soxCDYZ2 operon were detected when grown with cylcooctasulfur. Based on these findings a model for the oxidation of cylcooctasulfur is being proposed that might also apply to other Campylobacteria that share the same arrangement of the SOX system. Our results have implications for interpreting metatranscriptomic and -proteomic data and for the observed high level of diversification of soxYZ2 among sulfur-oxidizing Campylobacteria.
Chemoautotrophic bacteria belonging to the genus Sulfurimonas in the class Campylobacteria (formerly classified as Epsilonproteobacteria) play a key role in the sulfur cycle in a variety of oxygen-deficient or –limited and sulfide-rich marine and terrestrial environments. Previously, they were identified as key players in the turnover of zero-valence sulfur, a central intermediate in the marine sulfur cycle, and S. denitrificans was further shown to be able to oxidize cyclooctasulfur. However, at present the mechanism involved in the activation and metabolism of cyclooctasulfur is not known. To this end, we assessed the transcriptome and proteome of S. denitrificans grown with either thiosulfate or cyclooctasulfur as the electron donor. While the overall profiles under the two growth conditions were rather similar, distinct differences were observed that could be attributed to the utilization of cyclooctasulfur. This included a higher abundance of expressed genes and proteins related to attachment in the presence of cyclooctasulfur and the differential expression of the sulfur-oxidation multienzyme complex (SOX). S. denitrificans uses the SOX system for the oxidation of reduced sulfur compounds, including two copies of the sulfur-binding SoxYZ proteins, encoded in two gene clusters: soxABXYZ1 and soxCDYZ2. While the proteins of both operons of the SOX system were detected in the presence of thiosulfate, only proteins of the soxCDYZ2 operon were detected when grown with cylcooctasulfur. Based on these findings a model for the oxidation of cylcooctasulfur is being proposed that might also apply to other Campylobacteria that share the same arrangement of the SOX system. Our results have implications for interpreting metatranscriptomic and -proteomic data and for the observed high level of diversification of soxYZ2 among sulfur-oxidizing Campylobacteria.