Characterization of genes from a genomic signature for sporulation in the human gastrointestinal tract / Mariana Esperança Faustino Monteiro Barreira ; orient. Adriano O. Henriques, Mónica Serrano
Main Author Barreira, Mariana Esperança Faustino Monteiro Secondary Author Henriques, Adriano O.Serrano, Mónica Publication Lisboa : NOVA Medical School, 2019 Description xvi, 45 p. : il. Abstract About 50-60% of the bacteria in the human intestinal microbiota are anaerobic spore-forming organisms, that produce highly resilient spores. Spores allow the bacteria to persist in a variety of environments and transmission between hosts. For pathogenic spore formers, such as the anaerobe Clostridioides difficile, spores are central to dissemination, persistence, colonization and infection. A genomic signature for sporulation in the gut was recently identified, which contains 66 genes present in most sporulating organisms. Most are involved in spore morphogenesis and germination but about one third have unknown function. Here, we examined the expression pattern of four of the signature genes and established their dependencies on the cell type-specific sigma factors of sporulation, using C. difficile as a model gut organism. Of these, three showed cell-type-specific expression in sporulating cells: two are forespore-specific genes under the control of the early sigma factor sF and one is mother cell-specific, expressed under the control of the late sigma factor sK. We initiated the phenotypic characterization of the CD22730 gene, for which an inframe deletion mutation was obtained using a CRISPR/Cas9 system. The mutation resulted in increased sporulation. The spores of the mutant, however, showed reduced heat resistance, suggesting the involvement of CD22730 in spore cortex biogenesis. These spores were also smaller, with a thinner coat/exosporium layer. The compromised outermost layer, and in particular the reduced abundance of the CdeM protein, a determinant for the assembly of the exosporium and of a spore polar appendage, additionally suggests the involvement of CD22730 in proper assembly of the coat/exosporium. Our results pave the way for studies of the role of CD22730 in animal models of colonization infection, which will improve our understanding of the function of the sporulation signature genes and may also lead to novel strategies to antagonize C. difficile. Topical name Gastrointestinal Tract
Spores, Bacterial
Gene Transfer Techniques
Academic Dissertation
Portugal Index terms Dissertação de Mestrado
Microbiologia Médica
Universidade NOVA de Lisboa
NOVA Medical School
2019 CDU 616 Online Resources Click here to access the eletronic resource http://hdl.handle.net/10362/92374
| Item type | Current location | Call number | url | Status | Date due | Barcode |
|---|---|---|---|---|---|---|
| Documento Eletrónico | Biblioteca NMS|FCM online | RUN | http://hdl.handle.net/10362/92374 | Available | 20210023 |
About 50-60% of the bacteria in the human intestinal microbiota are anaerobic spore-forming organisms, that produce highly resilient spores. Spores allow the bacteria to persist in a variety of environments and transmission between hosts. For pathogenic spore formers, such as the anaerobe Clostridioides difficile, spores are central to dissemination, persistence, colonization and infection. A genomic signature for sporulation in the gut was recently identified, which contains 66 genes present in most sporulating organisms. Most are involved in spore morphogenesis and germination but about one third have unknown function. Here, we examined the expression pattern of four of the signature genes and established their dependencies on the cell type-specific sigma factors of sporulation, using C. difficile as a model gut organism. Of these, three showed cell-type-specific expression in sporulating cells: two are forespore-specific genes under the control of the early sigma factor sF and one is mother cell-specific, expressed under the control of the late sigma factor sK. We initiated the phenotypic characterization of the CD22730 gene, for which an inframe deletion mutation was obtained using a CRISPR/Cas9 system. The mutation resulted in increased sporulation. The spores of the mutant, however, showed reduced heat resistance, suggesting the involvement of CD22730 in spore cortex biogenesis. These spores were also smaller, with a thinner coat/exosporium layer. The compromised outermost layer, and in particular the reduced abundance of the CdeM protein, a determinant for the assembly of the exosporium and of a spore polar appendage, additionally suggests the involvement of CD22730 in proper assembly of the coat/exosporium. Our results pave the way for studies of the role of CD22730 in animal models of colonization infection, which will improve our understanding of the function of the sporulation signature genes and may also lead to novel strategies to antagonize C. difficile.
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