Biology subjects

Henriques, A. O.

Publications and source records attributed to Henriques, A. O..

2 recordsLinked to original sources

bioRxiv2018

Structure and assembly of a Clostridioides difficile spore polar appendage

Clostridioides difficile, a strict anaerobic spore-former, is the main cause of nosocomial disease associated to antibiotic therapy in adults and a growing concern in the community. Spores are the main infectious, persistence and transmission vehicle. Spore germination occurs in the intestine and the resulting vegetative cells will produce the toxins responsible for the disease symptoms, and spores. During sporulation, a wild type population bifurcates into two main spore morphotypes, with or without a thick exosporium. We show that this bifurcation extends to the formation of spores with a robust polar appendage or spores with a short appendage or that lack this structure. The cysteine-rich CdeM protein localizes to the appendage and around the entire surface of the spore, and is a major structural component of the exosporium, which we show is continuous with the appendage. In a CdeM mutant, when present, the polar appendage is short and disorganized. We show that wild type and cdeM spores with a short or no appendage germinate poorly in response to taurocholate, compared to those with an appendage. cdeM spores of the two types, however, germinate faster than their wild type counterparts. Thus, while the absence of CdeM may increase the permeability of spores to taurocholate, proper assembly of the appendage is also important for germination. Consistent with an overall enhancement of germination, a cdeM mutant shows increased virulence in a hamster model of disease. For a wild type population, spores with a short or no appendage germinate slower than the appendage-bearing spores. Differences in transmission, persistence and disease severity may result, in part, from their proportion in a spore population.

microbiology↗

bioRxiv2018

A protein phosphorylation module patterns the Bacillus subtilis spore outer coat

Assembly of the Bacillus subtilis spore coat involves over 80 protein components, which self-organize into a basal layer, a lamellar inner coat, a striated electrondense outer coat and a more external crust. CotB is an abundant component of the outer coat. Its C-terminal moiety contains a region, termed SKRB, formed by a series of serine-rich repeats, which we show is phosphorylated by the coat-associated Ser/Thr kinase CotH at multiple Ser residues. Another coat protein, CotG, which contains a central repeat region, SKRG, interacts with the C-terminal moiety of CotB and promotes its phosphorylation by CotH in vivo and in a heterologous system. CotG itself is phosphorylated by CotH but phosphorylation is enhanced in the absence of CotB. Spores of a cotHD288A strain, producing an inactive form of the kinase, like those formed by a cotG deletion mutant, lack the characteristic pattern of electrondense outer coat striations, while retaining the crust. Specifically, in the absence of CotG or CotH activity, most of the outer coat proteins are assembled but form a layer of amorphous material that peels-off the spore if crust formation is genetically ablated. In contrast, deletion of the SKRB region, has no major impact on the structure of the outer coat. Thus, phosphorylation of CotG by CotH is the principal factor establishing the structural pattern of the spore outer coat. The presence of the cotB/cotH/cotG cluster in several species closely related to B. subtilis and of cotG-like proteins in nearly all spore-formers that also code for a CotH homologue hints at the importance of this protein phosphorylation module in the morphogenesis of the spore outer layers.

microbiology↗