title: The SpoIIQ-SpoIIIAH complex of Clostridium difficile controls forespore engulfment and late stages of gene expression and spore morphogenesis.
abstract: Engulfment of the forespore by the mother cell is a universal feature of endosporulation. In Bacillus subtilis, the forespore protein SpoIIQ and the mother cell protein SpoIIIAH form a channel, essential for endosporulation, through which the developing spore is nurtured. The two proteins also form a backup system for engulfment. Unlike in B. subtilis, SpoIIQ of Clostridium difficile has intact LytM zinc-binding motifs. We show that spoIIQ or spoIIIAH deletion mutants of C. difficile result in anomalous engulfment, and that disruption of the SpoIIQ LytM domain via a single amino acid substitution (H120S) impairs engulfment differently. SpoIIQ and SpoIIQ(H120S) interact with SpoIIIAH throughout engulfment. SpoIIQ, but not SpoIIQ(H120S) , binds Zn(2+) , and metal absence alters the SpoIIQ-SpoIIIAH complex in vitro. Possibly, SpoIIQ(H120S) supports normal engulfment in some cells but not a second function of the complex, required following engulfment completion. We show that cells of the spoIIQ or spoIIIAH mutants that complete engulfment are impaired in post-engulfment, forespore and mother cell-specific gene expression, suggesting a channel-like function. Both engulfment and a channel-like function may be ancestral functions of SpoIIQ-SpoIIIAH while the requirement for engulfment was alleviated through the emergence of redundant mechanisms in B. subtilis and related organisms.
authors.affiliation: Microbial Development, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, Avenida da República, 2780-157, Oeiras, Portugal.
authors.forename: Mónica
authors.initials: M
authors.lastname: Serrano
authors.affiliation: Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Adam D
authors.initials: AD
authors.lastname: Crawshaw
authors.affiliation: Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.|MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK.
authors.forename: Marcin
authors.initials: M
authors.lastname: Dembek
authors.affiliation: Bacterial Cell Biology Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, Avenida da República, 2780-157, Oeiras, Portugal.
authors.forename: João M
authors.initials: JM
authors.lastname: Monteiro
authors.affiliation: Microbial Development, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, Avenida da República, 2780-157, Oeiras, Portugal.
authors.forename: Fátima C
authors.initials: FC
authors.lastname: Pereira
authors.affiliation: Bacterial Cell Biology Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, Avenida da República, 2780-157, Oeiras, Portugal.
authors.forename: Mariana Gomes
authors.initials: MG
authors.lastname: Pinho
authors.affiliation: MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK.
authors.forename: Neil F
authors.initials: NF
authors.lastname: Fairweather
authors.affiliation: Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Paula S
authors.initials: PS
authors.lastname: Salgado
authors.affiliation: Microbial Development, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Estação Agronómica Nacional, Avenida da República, 2780-157, Oeiras, Portugal.
authors.forename: Adriano O
authors.initials: AO
authors.lastname: Henriques
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016360:Clostridioides difficile / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017384:Sequence Deletion; D013171:Spores, Bacterial
chemical_list: D001426:Bacterial Proteins