Role of thessuandseuGenes ofCorynebacterium glutamicumATCC 13032 in Utilization of Sulfonates and Sulfonate Esters as Sulfur Sources

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Abstract
Corynebacterium glutamicumATCC 13032 was found to be able to utilize a broad range of sulfonates and sulfonate esters as sulfur sources. The two gene clusters potentially involved in sulfonate utilization,ssuD1CBAandssuI-seuABC-ssuD2, were identified in the genome ofC. glutamicumATCC 13032 by similarity searches. While thessugenes encode proteins resembling Ssu proteins fromEscherichia coliorBacillus subtilis, theseugene products exhibited similarity to the dibenzothiophene-degrading Dsz monooxygenases ofRhodococcusstrain IGTS8. Growth tests with theC. glutamicumwild-type and appropriate mutant strains showed that the clustered genesssuC,ssuB, andssuA, putatively encoding the components of an ABC-type transporter system, are required for the utilization of aliphatic sulfonates. InC. glutamicumsulfonates are apparently degraded by sulfonatases encoded byssuD1andssuD2. It was also found that theseugenesseuA,seuB, andseuCcan effectively replacessuD1andssuD2for the degradation of sulfonate esters. The utilization of all sulfonates and sulfonate esters tested is dependent on a novel putative reductase encoded byssuI. Obviously, all monooxygenases encoded by thessuandseugenes, including SsuD1, SsuD2, SeuA, SeuB, and SeuC, which are reduced flavin mononucleotide dependent according to sequence similarity, have SsuI as an essential component. Using real-time reverse transcription-PCR, thessuandseugene cluster was found to be expressed considerably more strongly during growth on sulfonates and sulfonate esters than during growth on sulfate.