Exosporium: Difference between revisions
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The '''exosporium''' is the outer surface layer of mature [[spores]]. In plant spores it is also referred to as the [[exine]]. Some [[bacteria]] also produce [[endospores]] with an exosporium, of which the most commonly studied are ''[[Bacillus]]'' species, particularly ''[[Bacillus cereus]]'' and the [[anthrax]]-causing bacterium ''[[Bacillus anthracis]]''. The exosporium is the portion of the spore that interacts with the [[Environment (biophysical)|environment]] or [[host (biology)|host organism]], and may contain spore [[antigen]]s.<ref name="redmond">{{cite journal|last1=Redmond|first1=C.|title=Identification of proteins in the exosporium of Bacillus anthracis|journal=Microbiology|date=2004|volume=150|issue=2|pages=355–363|doi=10.1099/mic.0.26681-0|pmid=14766913|url=http://mic.sgmjournals.org/content/150/2/355.long|doi-access=free}}</ref> Exosporium proteins, such as Cot protein, are also discovered related to strains of B. anthracis and B.cereus. This Cot protein share similar sequences with other spore coat proteins, and their putative determinants are believed to include bxpC, lunA, exsA, etc.<ref>{{cite journal|last1=Stewart|first1=George C.|title=The exosporium layer of bacterial spores: a connection to the environment and the infected host|journal=Microbiol. Mol. Biol. Rev.|date=December 1, 2015|volume=79|issue=4|page=437<!--|pages=457-->|doi=10.1128/MMBR.00050-15|pmid=26512126|pmc=4651027}}</ref> |
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The '''exosporium''' is the outer surface layer of mature [[spores]]. The exosporium represents the primary surface between the spore and its [[Environment (biophysical)|environment]] or [[host (biology)|host]], and is a site of spore [[antigen]]s. |
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In ''[[Bacillus anthracis]]'', [[salt]] and [[detergent]] washing of exosporium fragments can identify [[protein]]s that are likely to represent structural or integral exosporium proteins. Seven proteins have been identified in washed exosporium: [[alanine racemase]], [[inosine]] [[hydrolase]], ExsF, CotY, ExsY, CotB, and a novel protein, ExsK. CotY, ExsY and CotB are [[homology (biology)|homologues]] of [[Bacillus subtilis]] outer spore coat proteins, but ExsF and ExsK are specific to B. anthracis and other members of the [[Bacillus cereus]] group.<ref name="redmond" /> |
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The protein ywdL has been identified in ''B. cereus'' as important for exosporium formation. In the absence of the ywdL gene, a fragile and easily damaged exosporium is formed, which can be damaged by mechanical disruption such as [[freeze-thaw]] cycles. However, ywdL is not required to maintain the internal organization of the exosporium. ΔywdL spores have abnormal [[germination]] properties, such as the inability to respond to standard chemical means of inducing germination by treatment with [[Dipicolinic acid|calcium dipicolinate]].<ref>{{cite journal|last1=Terry|first1=Cassandra|last2=Shepherd|first2=Andrew|last3=Radford|first3=David S.|last4=Moir|first4=Anne|last5=Bullough|first5=Per A.|title=YwdL in Bacillus cereus: Its Role in Germination and Exosporium Structure|journal=PLOS ONE|date=2011|volume=6|issue=8|pages=e23801|doi=10.1371/journal.pone.0023801|pmid=21887322|pmc=3161080|bibcode=2011PLoSO...623801T|doi-access=free}}</ref> |
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==References== |
==References== |
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Latest revision as of 21:45, 29 January 2023
The exosporium is the outer surface layer of mature spores. In plant spores it is also referred to as the exine. Some bacteria also produce endospores with an exosporium, of which the most commonly studied are Bacillus species, particularly Bacillus cereus and the anthrax-causing bacterium Bacillus anthracis. The exosporium is the portion of the spore that interacts with the environment or host organism, and may contain spore antigens.[1] Exosporium proteins, such as Cot protein, are also discovered related to strains of B. anthracis and B.cereus. This Cot protein share similar sequences with other spore coat proteins, and their putative determinants are believed to include bxpC, lunA, exsA, etc.[2]
In Bacillus anthracis, salt and detergent washing of exosporium fragments can identify proteins that are likely to represent structural or integral exosporium proteins. Seven proteins have been identified in washed exosporium: alanine racemase, inosine hydrolase, ExsF, CotY, ExsY, CotB, and a novel protein, ExsK. CotY, ExsY and CotB are homologues of Bacillus subtilis outer spore coat proteins, but ExsF and ExsK are specific to B. anthracis and other members of the Bacillus cereus group.[1]
The protein ywdL has been identified in B. cereus as important for exosporium formation. In the absence of the ywdL gene, a fragile and easily damaged exosporium is formed, which can be damaged by mechanical disruption such as freeze-thaw cycles. However, ywdL is not required to maintain the internal organization of the exosporium. ΔywdL spores have abnormal germination properties, such as the inability to respond to standard chemical means of inducing germination by treatment with calcium dipicolinate.[3]
References[edit]
- ^ a b Redmond, C. (2004). "Identification of proteins in the exosporium of Bacillus anthracis". Microbiology. 150 (2): 355–363. doi:10.1099/mic.0.26681-0. PMID 14766913.
- ^ Stewart, George C. (December 1, 2015). "The exosporium layer of bacterial spores: a connection to the environment and the infected host". Microbiol. Mol. Biol. Rev. 79 (4): 437. doi:10.1128/MMBR.00050-15. PMC 4651027. PMID 26512126.
- ^ Terry, Cassandra; Shepherd, Andrew; Radford, David S.; Moir, Anne; Bullough, Per A. (2011). "YwdL in Bacillus cereus: Its Role in Germination and Exosporium Structure". PLOS ONE. 6 (8): e23801. Bibcode:2011PLoSO...623801T. doi:10.1371/journal.pone.0023801. PMC 3161080. PMID 21887322.
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