KipOTIA detoxifies 5-oxoproline and promotes the growth ofClostridioides difficile

Abstract

ABSTRACTClostridioides difficileis an anaerobic enteric pathogen that disseminates in the environment as a dormant spore. ForC. difficileand other sporulating bacteria, the initiation of sporulation is a regulated process that prevents spore formation under favorable growth conditions. InBacillus subtilis, one such mechanism for preventing sporulation is the Kinase Inhibitory Protein, KipI, which impedes activation of the main sporulation kinase. In addition, KipI functions as part of a complex that detoxifies the intermediate metabolite, 5-oxoproline (OP), a harmful by-product of glutamic acid. In this study, we investigate the orthologous Kip proteins inC. difficileto determine their roles in the regulation of sporulation and metabolism. Using deletion mutants inkipIAand the fullkipOTIAoperon, we show that unlike inB. subtilis,the Kip proteins have no significant impact on sporulation. However, we found that thekipoperon encodes a functional oxoprolinase that facilitates detoxification of OP. Further, our data demonstrate that KipOTIA not only detoxifies OP, but also allows OP to be used as a nutrient source that supports the robust growth ofC. difficile, thereby facilitating the conversion of a toxic byproduct of metabolism into an effective energy source.