Fig. 1
Overview of the taurine desulfonation pathway in B. wadsworthia 3.1.6, as revealed previously [1, 26, 27], and of the key enzymes of the pathway enclosed in bacterial microcompartments (BMCs), as inferred from the results of this study (A) Illustration of the taurine degradation pathway via isethionate desulfonation by a glycyl radical enzyme and the subsequent conversion of the acetaldehyde released from isethionate to acetate, and of the reduction of the sulfite released to H2S by the dissimilatory sulfite reductase complex. The involvement of BMCs in this pathway, as inferred from the results of this study, is also indicated (see main text). Please note that H2S, HS- and to a small extent S2- are in equilibrium at physiological pH, but that H2S will be used throughout this study to refer to all three species. Enzyme abbreviations used: Tpa, taurine-pyruvate aminotransferase; Ald, alanine dehydrogenase; SarD, sulfoacetaldehyde reductase; IslAB, isethionate-sulfite lyase; AdhE, acetylating acetaldehyde dehydrogenase; Pta, phosphotransacetylase; AckA, acetate kinase; Dsr, dissimilatory sulfite reductase. (B) The gene cluster in B. wadsworthia 3.1.6 encoding isethionate sulfite-lyase IslAB (Integrated Microbial Genomes (IMG) locus tags HMPREF0179_00638 and _00639) and BMC-associated proteins. Genes marked in red are genes for catabolic enzymes, genes marked in orange encode BMC shell proteins, and genes marked in green may encode proteins that we suspect to be involved in maintaining the redox balance within the BMC (see Discussion). The detailed description for each gene can be found in Table 1