Thioester protein crosslinks: Difference between revisions
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[https://en.wikipedia.org/wiki/Thioester Thioester bonds] between cysteine and glutamine sidechains can form covalent cross-links between polypeptide chains. Thioester bonds are one way that ubiquitin may be attached to proteins ([https://en.wikipedia.org/wiki/Ubiquitin ubiquitinylation]). Thioester bonds in [https://en.wikipedia.org/wiki/Complement_system complement proteins] C3 and C4 are involved in tagging pathogens for destruction by the immune system, via the alternate complement activation pathway. | <StructureSection load='' size='350' side='right' caption='' scene='88/886048/Thioester1_2xi9/1'> | ||
[https://en.wikipedia.org/wiki/Thioester Thioester bonds] between cysteine and glutamine sidechains can form covalent cross-links between polypeptide chains. An accurate estimate of the number of thioester bonds in the [[PDB]] may not be available (see [[Protein crosslinks#Thioester Crosslinks]]). A search for "thioester" in Proteopedia yields >500 hits. | |||
*Thioester bonds are one way that ubiquitin may be attached to proteins ([https://en.wikipedia.org/wiki/Ubiquitin ubiquitinylation]; see also [[Ubiquitin and Ubiquitination]]). | |||
*Thioester bonds in [https://en.wikipedia.org/wiki/Complement_system complement proteins] C3 and C4 are involved in tagging pathogens for destruction by the immune system, via the alternate complement activation pathway. Example: [[2b39]]. | |||
*Thioester bonds occur in thioester domains (TED) of Gram-positive bacteria, where they are thought to mediate covalent adhesion of bacteria to host cells<ref name="nakata2021">PMID:33633705</ref><ref name="slipknot">PMID: 30052296</ref>, or to participate in bacterial conjugation involved in antibiotic resistance<ref name="gago-cordoba">PMID: 33727345</ref>. Many surface proteins of Gram-positive bacteria are predicted to contain TED as well as [[isopeptide bond|isopeptide]] and ester cross-links. This family of proteins is termed <b>TIE proteins</b> for thioester, isopeptide, ester proteins<ref name="slipknot" />. Examples: [[2xi9]], [[6fwy]]. | |||
**In a dramatic example, the pilus tip adhesin of ''Streptococcus pyogenes'' forms dimers in the presence of spermidine, a di-amine that forms thiopeptide bonds with the Gln211 residues in two adhesin protein chains, illustrated in [[4c0z]]<ref name="linke-winnebeck2014">PMID: 24220033</ref>. | |||
</StructureSection> | |||
==Detection and Visualization== | |||
[[FirstGlance in Jmol]] alerts you to protein crosslinks when present, and provides convenient links that zoom in and and display each one in detail. Viewing the [[electron density map]] is just one more click. Use the links above to 4-character [[PDB codes]] to go to a Proteopedia page titled with that 4-character [[PDB code]]. There, click on "FirstGlance". In FirstGlance, click on the Tools tab, and there, on "Protein Crosslinks". See the practical guide [[FirstGlance/Evaluating Protein Crosslinks]]. | |||
==Other Protein Crosslinks== | |||
In addition to the thioester bonds discussed above, other [[Protein crosslinks|covalent cross-links between polypeptide chains]] include: | |||
*[[Disulfide bond]]s | |||
*[[Isopeptide bond]]s | |||
*[[Thioether protein crosslinks]] | |||
*[[Ester protein crosslinks]] | |||
*[[Histidine-tyrosine protein crosslinks]] | |||
*[[Lysine-cysteine NOS bonds]] | |||
==References== | |||
<references /> | |||