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  • Differential requirements f...
    Ribis, John W.; Fimlaid, Kelly A.; Shen, Aimee

    Molecular microbiology, November 2018, 2018-11-00, 20181101, Letnik: 110, Številka: 3
    Journal Article

    Summary Spore formation is essential for the bacterial pathogen and obligate anaerobe, Clostridioides (Clostridium) difficile, to transmit disease. Completion of this process depends on the mother cell engulfing the developing forespore, but little is known about how engulfment occurs in C. difficile. In Bacillus subtilis, engulfment is mediated by a peptidoglycan degradation complex consisting of SpoIID, SpoIIP and SpoIIM, which are all individually required for spore formation. Using genetic analyses, we determined the functions of these engulfment‐related proteins along with the putative endopeptidase, SpoIIQ, during C. difficile sporulation. While SpoIID, SpoIIP and SpoIIQ were critical for engulfment, loss of SpoIIM minimally impacted C. difficile spore formation. Interestingly, a small percentage of ∆spoIID and ∆spoIIQ cells generated heat‐resistant spores through the actions of SpoIIQ and SpoIID, respectively. Loss of SpoIID and SpoIIQ also led to unique morphological phenotypes: asymmetric engulfment and forespore distortions, respectively. Catalytic mutant complementation analyses revealed that these phenotypes depend on the enzymatic activities of SpoIIP and SpoIID, respectively. Lastly, engulfment mutants mislocalized polymerized coat even though the basement layer coat proteins, SpoIVA and SipL, remained associated with the forespore. Collectively, these findings advance our understanding of several stages during infectious C. difficile spore assembly. Spore formation is essential for the bacterial pathogen Clostridium difficile to transmit disease. A critical step during this process is the engulfment of the developing spore. In Bacillus subtilis, SpoIID, SpoIIPand SpoIIM are essential for engulfment, but we show here that SpoIIM is dispensable for C. difficile spore formation, and SpoIID is only partially required. SpoIID’s enzymatic activity also causes morphological defects in ‘feeding tube’‐mutants. Thus, conserved proteins can have differential functions in spore‐formers.