3 results on '"Olivença, Carmen"'
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2. Functional characterization of a cysteine protease essential for the assembly of the Clostridioides difficile spore surface layers
- Author
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Olivença, Carmen Maria Antunes, Henriques, Adriano, and Serrano, Mónica
- Subjects
Clostridioides difficile ,Repressor ,Spore surface layers ,Engenharia e Tecnologia::Outras Engenharias e Tecnologias [Domínio/Área Científica] ,YabG ,Cysteine protease - Abstract
Clostridioides difficile is a Gram-positive, strict anaerobe, sporeforming organism, and the leading cause of a range of intestinal diseases linked to antibiotic therapy. C. difficile infection begins with the ingestion of spores that are also the vehicle for transmission. Proper assembly of the spore surface layers is important for the resilience of spores, their interaction with host cells and proper germination. Here, we focused on the characterization of YabG, a cysteine protease conserved among spore-formers. YabG processes substrates involved in spore germination and is required for the transcription of a gene, cdeM, which codes for a protein with a key role in the structural organization of the spore surface and required for host colonization. YabG has an N-terminal domain separated by a linker with a hinge region, from a C-terminal catalytic domain with the fold of a response regulator. We showed that unlike other cysteine proteases, YabG does not require removal of the N-terminal domain for activity. Rather, we present data suggesting that this domain is important for substrate engagement. Nevertheless, a catalytic inactive variant is cleaved in trans by the WT enzyme, at one of several arginine residues located in the hinge region. Multiple arginine to alanine substitutions in this region, result in a form of YabG able to process its substrates in vitro and in vivo but that fails to activate cdeM transcription. YabG may function by removing a cdeM repressor. Consistent with this model, we found two direct repeats in the cdeM regulatory region that function in cis to bind a repressor. Accordingly, titrating the repressor bypasses the need for YabG. Given its central role in spore assembly and its unique structural and functional features, YabG is an attractive therapeutical target to interfere with the central role of spores in infection and transmission. Clostridioides difficile é uma bactéria Gram-positiva anaeróbia esporulante e a principal causa de doenças intestinais associadas à toma de antibióticos. A infecção por C. difficile começa com a ingestão de esporos, que são também veículos de transmissão. A montagem adequada das camadas superficiais dos esporos é importante para a sua resiliência, a interação com as células hospedeiras e germinação adequada. Neste estudo, concentrámo-nos na caracterização de YabG, uma protease de cisteína conservada entre bactérias esporulantes. YabG processa substratos envolvidos na germinação de esporos e é necessário para a transcrição de cdeM, que codifica para uma proteína com um papel fundamental na organização das camadas superficiais do esporo e necessária para a colonização do hospedeiro. YabG tem um domínio N-terminal separado por uma região flexível de um domínio catalítico C-terminal, que possui uma conformação de um regulador de resposta. Ao contrário de outras proteases de cisteína, YabG não requer a remoção do domínio N-terminal para atividade. Em vez disso, apresentamos dados que sugerem que este domínio é importante para interação com substratos. Adicionalmente, uma variante catalítica inativa é clivada em trans pela enzima WT num dos vários resíduos de arginina localizados na região flexível. Múltiplas substituições de arginina por alanina nesta região, resultam numa forma de YabG capaz de processar substratos in vitro e in vivo, mas que falha em ativar a transcrição de cdeM. YabG pode funcionar removendo um repressor de cdeM. Consistente com este modelo, encontrámos duas repetições diretas na região reguladora de cdeM, que funcionam em cis para ligar um repressor. Consequentemente, a titulação do repressor transpôs a necessidade de YabG na transcrição. Assim, dado o seu papel central na montagem de esporos e as suas características estruturais e funcionais únicas, YabG é um alvo terapêutico atraente interferindo no papel central dos esporos na infecção e transmissão.
- Published
- 2022
3. The impact of YabG mutations on C. difficile spore germination and processing of spore substrates.
- Author
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Osborne MS, Brehm JN, Olivença C, Cochran AM, Serrano M, Henriques AO, and Sorg JA
- Abstract
YabG is a sporulation-specific protease that is conserved among sporulating bacteria. C. difficile YabG processes cortex destined proteins preproSleC into proSleC and CspBA to CspB and CspA. YabG also affects synthesis of spore coat/exosporium proteins CotA and CdeM. In prior work that identified CspA as the co-germinant receptor, mutations in yabG were found which altered the co-germinants required to initiate spore germination. To understand how these mutations in the yabG locus contribute to C. difficile spore germination, we introduced these mutations into an isogenic background. Spores derived from C. difficile yabG
C207A (catalytically inactive), C. difficile yabGA46D , C. difficile yabGG37E , and C. difficile yabGP153L strains germinated in response to TA alone. Recombinantly expressed and purified preproSleC incubated with E. coli lysate expressing wild type YabG resulted in the removal of the pre sequence from preproSleC. Interestingly, only YabGA46D showed any activity towards purified preproSleC. Mutation of the YabG processing site in preproSleC (R119A) led to YabG shifting its processing to R115 or R112. Finally, changes in yabG expression under the mutant promoters were analyzed using a SNAP-tag and revealed expression differences at early and late stages of sporulation. Overall, our results support and expand upon the hypothesis that YabG is important for germination and spore assembly and, upon mutation of the processing site, can shift where it cleaves substrates., Competing Interests: Conflict of interest The authors declare no conflict of interest.- Published
- 2024
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