Cysteine–Lysine Crosslink Serves as Redox Switch in Enzyme

  • Author:
  • Published: 06 June 2021
  • Copyright: Wiley-VCH GmbH
thumbnail image: Cysteine–Lysine Crosslink Serves as Redox Switch in Enzyme

In proteins, disulfide bridges can form between cysteine residues and stabilize the overall three-dimensional structure. In contrast to most other interactions between protein chains, these bridges are formed by covalent bonds. Disulfide bridges can be reversibly formed and broken by redox reactions. This means they can be used as "redox switches" to influence protein structure and function.

Kai Tittmann, University of Göttingen and Max Planck Institute for Biophysical Chemistry, Göttingen, Germany, and colleagues have found a second type of cysteine-based redox switch with a covalent crosslink in proteins: an N–O–S bridge formed between a cysteine and a lysine residue (pictured, cysteine on the left, lysine on the right). The team investigated a transaldolase enzyme from the human pathogen Neisseria gonorrhoeae, which causes gonorrhea. This enzyme's activity can be "switched" on or off by reducing or oxidizing it, respectively. The researchers crystallized this protein under either oxidizing or reducing conditions and recorded X-ray structures.

In the oxidized state of the protein, the team found a crosslink between a cysteine and a lysine residue with a bridging oxygen atom. In the reduced state, this covalent N–O–S bridge was absent. According to the researchers, the N–O–S bridge is not unique to the studied transaldolase, but might also exist in other proteins. They searched the Protein Data Bank (PDB) for suitable structures and identified several proteins that are likely to possess this type of bridge.



Article Views: 609

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

If you would like to reuse any content, in print or online, from, please contact us first for permission. more

Follow on Facebook Follow on Twitter Follow on YouTube Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

Magazine of Chemistry Europe (16 European Chemical Societies) published by Wiley-VCH