Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism

ABSTRACT 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 rehydrat...

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Autores principales:	Michael B. Francis, Joseph A. Sorg
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	Clostridium difficile DPA cortex dipicolinic acid germination mechanosensing Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/0f4450078fb14fbcac4206b8e7f645e4
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spelling	oai:doaj.org-article:0f4450078fb14fbcac4206b8e7f645e42021-11-15T15:22:04ZDipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism10.1128/mSphere.00306-162379-5042https://doaj.org/article/0f4450078fb14fbcac4206b8e7f645e42016-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00306-16https://doaj.org/toc/2379-5042ABSTRACT 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.Michael B. FrancisJoseph A. SorgAmerican Society for MicrobiologyarticleClostridium difficileDPAcortexdipicolinic acidgerminationmechanosensingMicrobiologyQR1-502ENmSphere, Vol 1, Iss 6 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Clostridium difficile DPA cortex dipicolinic acid germination mechanosensing Microbiology QR1-502
spellingShingle	Clostridium difficile DPA cortex dipicolinic acid germination mechanosensing Microbiology QR1-502 Michael B. Francis Joseph A. Sorg Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
description	ABSTRACT 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	article
author	Michael B. Francis Joseph A. Sorg
author_facet	Michael B. Francis Joseph A. Sorg
author_sort	Michael B. Francis
title	Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
title_short	Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
title_full	Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
title_fullStr	Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
title_full_unstemmed	Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism
title_sort	dipicolinic acid release by germinating <named-content content-type="genus-species">clostridium difficile</named-content> spores occurs through a mechanosensing mechanism
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/0f4450078fb14fbcac4206b8e7f645e4
work_keys_str_mv	AT michaelbfrancis dipicolinicacidreleasebygerminatingnamedcontentcontenttypegenusspeciesclostridiumdifficilenamedcontentsporesoccursthroughamechanosensingmechanism AT josephasorg dipicolinicacidreleasebygerminatingnamedcontentcontenttypegenusspeciesclostridiumdifficilenamedcontentsporesoccursthroughamechanosensingmechanism
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Dipicolinic Acid Release by Germinating <named-content content-type="genus-species">Clostridium difficile</named-content> Spores Occurs through a Mechanosensing Mechanism

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