Cargando…

Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism

Classically, dormant endospores are defined by their resistance properties, particularly their resistance to heat. Much of the heat resistance is due to the large amount of dipicolinic acid (DPA) stored within the spore core. During spore germination, DPA is released and allows for rehydration of th...

Descripción completa

Detalles Bibliográficos
Autores principales: Francis, Michael B., Sorg, Joseph A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5156672/
https://www.ncbi.nlm.nih.gov/pubmed/27981237
http://dx.doi.org/10.1128/mSphere.00306-16
_version_ 1782481298726584320
author Francis, Michael B.
Sorg, Joseph A.
author_facet Francis, Michael B.
Sorg, Joseph A.
author_sort Francis, Michael B.
collection PubMed
description Classically, dormant endospores are defined by their resistance properties, particularly their resistance to heat. Much of the heat resistance is due to the large amount of dipicolinic acid (DPA) stored within the spore core. During spore germination, DPA is released and allows for rehydration of the otherwise-dehydrated core. In Bacillus subtilis, 7 proteins are encoded by the spoVA operon and are important for DPA release. These proteins receive a signal from the activated germinant receptor and release DPA. This DPA activates the cortex lytic enzyme CwlJ, and cortex degradation begins. In Clostridium difficile, spore germination is initiated in response to certain bile acids and amino acids. These bile acids interact with the CspC germinant receptor, which then transfers the signal to the CspB protease. Activated CspB cleaves the cortex lytic enzyme, pro-SleC, to its active form. Subsequently, DPA is released from the core. C. difficile encodes orthologues of spoVAC, spoVAD, and spoVAE. Of these, the B. subtilis SpoVAC protein was shown to be capable of mechanosensing. Because cortex degradation precedes DPA release during C. difficile spore germination (opposite of what occurs in B. subtilis), we hypothesized that cortex degradation would relieve the osmotic constraints placed on the inner spore membrane and permit DPA release. Here, we assayed germination in the presence of osmolytes, and we found that they can delay DPA release from germinating C. difficile spores while still permitting cortex degradation. Together, our results suggest that DPA release during C. difficile spore germination occurs though a mechanosensing mechanism. IMPORTANCE Clostridium difficile is transmitted between hosts in the form of a dormant spore, and germination by C. difficile spores is required to initiate infection, because the toxins that are necessary for disease are not deposited on the spore form. Importantly, the C. difficile spore germination pathway represents a novel pathway for bacterial spore germination. Prior work has shown that the order of events during C. difficile spore germination (cortex degradation and DPA release) is flipped compared to the events during B. subtilis spore germination, a model organism. Here, we further characterize the C. difficile spore germination pathway and summarize our findings indicating that DPA release by germinating C. difficile spores occurs through a mechanosensing mechanism in response to the degradation of the spore cortex.
format Online
Article
Text
id pubmed-5156672
institution National Center for Biotechnology Information
language English
publishDate 2016
publisher American Society for Microbiology
record_format MEDLINE/PubMed
spelling pubmed-51566722016-12-15 Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism Francis, Michael B. Sorg, Joseph A. mSphere Research Article Classically, dormant endospores are defined by their resistance properties, particularly their resistance to heat. Much of the heat resistance is due to the large amount of dipicolinic acid (DPA) stored within the spore core. During spore germination, DPA is released and allows for rehydration of the otherwise-dehydrated core. In Bacillus subtilis, 7 proteins are encoded by the spoVA operon and are important for DPA release. These proteins receive a signal from the activated germinant receptor and release DPA. This DPA activates the cortex lytic enzyme CwlJ, and cortex degradation begins. In Clostridium difficile, spore germination is initiated in response to certain bile acids and amino acids. These bile acids interact with the CspC germinant receptor, which then transfers the signal to the CspB protease. Activated CspB cleaves the cortex lytic enzyme, pro-SleC, to its active form. Subsequently, DPA is released from the core. C. difficile encodes orthologues of spoVAC, spoVAD, and spoVAE. Of these, the B. subtilis SpoVAC protein was shown to be capable of mechanosensing. Because cortex degradation precedes DPA release during C. difficile spore germination (opposite of what occurs in B. subtilis), we hypothesized that cortex degradation would relieve the osmotic constraints placed on the inner spore membrane and permit DPA release. Here, we assayed germination in the presence of osmolytes, and we found that they can delay DPA release from germinating C. difficile spores while still permitting cortex degradation. Together, our results suggest that DPA release during C. difficile spore germination occurs though a mechanosensing mechanism. IMPORTANCE Clostridium difficile is transmitted between hosts in the form of a dormant spore, and germination by C. difficile spores is required to initiate infection, because the toxins that are necessary for disease are not deposited on the spore form. Importantly, the C. difficile spore germination pathway represents a novel pathway for bacterial spore germination. Prior work has shown that the order of events during C. difficile spore germination (cortex degradation and DPA release) is flipped compared to the events during B. subtilis spore germination, a model organism. Here, we further characterize the C. difficile spore germination pathway and summarize our findings indicating that DPA release by germinating C. difficile spores occurs through a mechanosensing mechanism in response to the degradation of the spore cortex. American Society for Microbiology 2016-12-14 /pmc/articles/PMC5156672/ /pubmed/27981237 http://dx.doi.org/10.1128/mSphere.00306-16 Text en Copyright © 2016 Francis and Sorg. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Research Article
Francis, Michael B.
Sorg, Joseph A.
Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title_full Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title_fullStr Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title_full_unstemmed Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title_short Dipicolinic Acid Release by Germinating Clostridium difficile Spores Occurs through a Mechanosensing Mechanism
title_sort dipicolinic acid release by germinating clostridium difficile spores occurs through a mechanosensing mechanism
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5156672/
https://www.ncbi.nlm.nih.gov/pubmed/27981237
http://dx.doi.org/10.1128/mSphere.00306-16
work_keys_str_mv AT francismichaelb dipicolinicacidreleasebygerminatingclostridiumdifficilesporesoccursthroughamechanosensingmechanism
AT sorgjosepha dipicolinicacidreleasebygerminatingclostridiumdifficilesporesoccursthroughamechanosensingmechanism