Publication Date:
2016-09-02
Description:
Sulfur is an essential element for growth and many physiological functions. As sulfur sources for Escherichia coli and related bacteria, specific transporters import various sulfur-containing compounds from the environment. In this study, we identified and characterized an alternative function of the cystine transporter YdjN in E. coli as a transporter of S -sulfocysteine, a sulfur-containing intermediate in the assimilatory cysteine biosynthesis that is used as a sulfur source for the growth of E. coli . We also demonstrated that the transport of S -sulfocysteine via YdjN depends on the transcriptional regulator CysB, a master regulator that controls most of the genes involved in sulfur assimilation and cysteine metabolism. We found that the use of S -sulfocysteine as a sulfur source depends on glutathione because mutations in glutathione biosynthetic genes abolish growth when S -sulfocysteine is used as a sole sulfur source, thereby supporting the previous findings that the conversion of S -sulfocysteine to cysteine is catalyzed by glutaredoxins. To the best of our knowledge, this is the first report of a functional S -sulfocysteine transporter across organisms, which strongly supports the hypothesis that S -sulfocysteine is not only a metabolic intermediate but also a physiologically significant substance in specific natural environments.
Keywords:
Physiology & Biochemistry
Print ISSN:
0378-1097
Electronic ISSN:
1574-6968
Topics:
Biology
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