Authors: Kerstin Hermuth Birgitta Leuthner Johann Heider
Publish Date: 2001/12/01
Volume: 177, Issue: 2, Pages: 132-138
Abstract
The first step in anaerobic toluene degradation is the addition of a fumarate cosubstrate to the methyl group of toluene as catalyzed by the glycyl radical enzyme benzylsuccinate synthase The bssDCAB genes code for the subunits of benzylsuccinate synthase BssA B and C and an additional enzyme implicated in activating the enzyme by introducing the glycyl radical BssD Quantitation of the amounts of benzylsuccinate synthase and activating enzyme showed that both proteins are only synthesized in toluenegrown cells and that the activating enzyme is present in about 14fold lower amounts Two mRNA species of the bss gene cluster were identified one beginning in front of bssD and a second in front of bssC Only the first mRNA 5′end correlates with a tolueneinduced promoter which is similar to that preceding the bbs operon coding for the further enzymes of toluene catabolism of the same strain The second mapped 5′end appears to be generated by endonucleolytic processing The mRNA segment containing the bssD gene is very shortlived while that containing the bssCAB genes is more stable The RNA stability data are consistent with the observed amounts of encoded gene products Furthermore the previously known bssDCAB genes are apparently cotranscribed with a fifth gene bssE whose product may function as a putative ATPdependent chaperone for assembly and/or activation of benzylsuccinate synthase
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