User:Davi de Souza/Sandbox 1

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<StructureSection load='5jzt' size='340' side='right' caption='Oligomer strucuture of Aerolysin' scene=''>
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<StructureSection load='5jzt' size='360' side='right' caption='Oligomer structure of Aerolysin' scene=''>
== Structure ==
== Structure ==
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Aerolysin is a pore-forming protein (PFT) belonging to the beta-PFT family. It is a protein that is secreted by the bacterium as a water-soluble protein. It binds to receptors on its target cell membrane and, upon proteolytic activation, forms oligomers that insert into the plasma membrane. The soluble monomer has a molecular weight of 52 kDa, and its structure has been resolved by X-ray crystallography.
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Aerolysin proprotein is a protein that consists of 4 domains:
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Its secondary structure is predominantly composed of <scene name='97/973994/Betasheet/1'>beta sheets</scene>. These beta sheets fold and organize into a characteristic conformation, forming a <scene name='97/973994/Folhasbetas/1'>hollow cylindrical</scene> structure. This cylindrical conformation is functionally important as it allows the protein to permeabilize the cell membrane and form pores. Regarding the tertiary structure, aerolysin is a compact globular protein. It has several antiparallel beta helices that organize into a cylindrical structure, enclosing a central cavity. This central cavity is believed to be the region responsible for the protein's interaction with the cell membrane and pore formation. As for the quaternary structure, aerolysin is typically found in an oligomeric configuration, with the active form consisting of 4 to 7 <scene name='97/973994/Monomero_2/1'>subunits</scene> that associate to form the quaternary complex.
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Domains 1 and 2 are responsible for binding to N-glycosylated phosphatidylinositol (GPI) proteins, which are present in the membranes of eukaryotic cells. Domain 1 binds to specific sugar modifications found on the GPI receptor, while domain 2 directly binds to the glycan core located in the central portion of GPI proteins. Therefore, both domain 1 and domain 2 are involved in anchoring the aerolysin proprotein to the target cell membrane.
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Regarding the functional domains, it is known that aerolysin has 4 domains. Domains 1 and 2 are responsible for binding to glycosylphosphatidylinositol (GPI) proteins, which act as aerolysin receptors. Domain 2 binds directly to the GPI anchor glycan core, while domain 1 binds to sugar modifications present on the receptor. Domain 3 consists of a five-stranded beta sheet and a pre-stem loop, which is curled against the beta sheet to form the transmembrane beta barrel. Domain 4 is an extension of the beta sheet of domain 3 and is opened by the C-terminal peptide (CTP) into a twisted double-fold of the beta sheet. The CTP is a propeptide present in the secreted form of aerolysin and needs to be cleaved by proteases for the toxin to be activated. The protein has a predominant beta sheet (β) structure, comprising 40% of its composition, and 17% alpha helix (α)<ref>PMID: 27405240</ref><ref>PMID: 7510043</ref><ref>DOI 10.1002/ijch.201300024</ref><ref>PMID:21638687</ref>.
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Domain 3 is composed of a five-stranded beta sheet and a pre-stem loop, which are important for the insertion and anchoring of the protein into the cell membrane.
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This is a sample scene created with SAT to <scene name="/12/3456/Sample/1">color</scene> by Group, and another to make <scene name="/12/3456/Sample/2">a transparent representation</scene> of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.
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Domain 4 is an extension of the beta sheet from domain 3, but it is opened by the C-terminal peptide (CTP), forming a twisted double-fold in the beta sheet. This conformational change induced by the CTP propeptide allows the protein to fold into its soluble form. When the CTP is cleaved from the main body of the protein, the proaerolisin oligomerizes into a heptameric ring on the target cell membrane, forming a pore.
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During proaerolisin oligomerization, domain 1 undergoes rotation, allowing all receptor binding sites to position themselves correctly relative to the target membrane. Domains 2 and 3 remain largely unchanged. On the other hand, domain 4, after cleavage of the CTP propeptide, undergoes rearrangement of the beta sheets, forming a beta sandwich. In the core of this sandwich, hydrophobic residues are internalized. Additionally, domain 4 rotates relative to domain 3, enabling hydrogen bonding between the beta sandwiches of two monomers, promoting the oligomerization of aerolysin.
</StructureSection>
</StructureSection>

Revision as of 18:48, 25 June 2023

Abstract

Aerolysin is a protein synthesized by some species of bacteria belonging to the genus Aeromonas, such as Aeromonas hydrophila. The exact function of Aerolysin may vary among different species and strains of Aeromonas. However, it is evident that it is the main macromolecule responsible for the pathogenicity of Aeromonas hydrophila, being associated with diarrheal diseases and deep wound infections [1].

Function

Aerolysin plays several roles in the pathogenicity of Aeromonas spp. One of its main functions is its ability to promote lysis (rupture) of host cells, such as epithelial cells and immune cells. Aerolysin exhibits cytotoxic activity, causing damage to the cell membranes of host cells, which can lead to cell death and contribute to the bacterium's pathogenicity. Furthermore, aerolysin may be involved in the invasion and dissemination of the bacterium within the host. It can assist in tissue degradation, facilitating the bacterium's invasion into different organs and tissues of the host. It is important to note that the exact function of aerolysin may vary among different species and strains of Aeromonas. Additionally, there are other proteins and virulence factors produced by Aeromonas spp. that also play important roles in the pathogenicity of these bacteria.


Oligomer structure of Aerolysin

Drag the structure with the mouse to rotate

References

  1. Altwegg M, Geiss HK. Aeromonas as a human pathogen. Crit Rev Microbiol. 1989;16(4):253-86. PMID:2649316 doi:10.3109/10408418909105478

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Proteopedia Page Contributors and Editors (what is this?)

Davi de Souza

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