Lysine-cysteine NOS bonds
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==Methods== | ==Methods== | ||
| - | This is a summary of the observations supporting the NOS bond<ref name="wensien2021" />. [[6zx4]] (oxidized form, NOS present) has a [[resolution]] of 0.96 Å, with a better than average [[Rfree|R<sub>free</sub>]] of 0.136. ''Neisseria gonorrhoeae'' transaldolase has 3 cysteines (no disulfide bonds). It does not form disulfide-linked oligomers. | + | This is a summary of the observations supporting the NOS bond<ref name="wensien2021" />. [[6zx4]] (oxidized form, NOS present) has a [[resolution]] of 0.96 Å, with a better than average [[Rfree|R<sub>free</sub>]] of 0.136. ''Neisseria gonorrhoeae'' transaldolase has 3 cysteines (no disulfide bonds). It does not form disulfide-linked oligomers. Mutations of each Cys to Ser. Only the mutation Cys38Ser abolished redox control, producing a constitutively active enzyme. |
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| + | Electron density for an unidentified atom appeared between the sidechain nitrogen of Lys8 and the sulfur of Cys38 for several crystals under nonreducing conditions, as well as in data from a low-dose non-synchrotron source, arguing against a radiation damage artifact. Competitive refinements indicated that the unidentified atom was oxygen, rather than carbon. | ||
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| + | In crystals of reduced (inactive) enzyme, the Lys8-O-Cys38 bridge was absent. However, electron density near the Cys38 sulfur was consistent with molecular oxygen O<sub>2</sub>. Molecular oxygen was absent in this position in the oxidized (active) enzyme. | ||
==References== | ==References== | ||
<references /> | <references /> | ||
Revision as of 18:23, 26 May 2021
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Methods
This is a summary of the observations supporting the NOS bond[1]. 6zx4 (oxidized form, NOS present) has a resolution of 0.96 Å, with a better than average Rfree of 0.136. Neisseria gonorrhoeae transaldolase has 3 cysteines (no disulfide bonds). It does not form disulfide-linked oligomers. Mutations of each Cys to Ser. Only the mutation Cys38Ser abolished redox control, producing a constitutively active enzyme.
Electron density for an unidentified atom appeared between the sidechain nitrogen of Lys8 and the sulfur of Cys38 for several crystals under nonreducing conditions, as well as in data from a low-dose non-synchrotron source, arguing against a radiation damage artifact. Competitive refinements indicated that the unidentified atom was oxygen, rather than carbon.
In crystals of reduced (inactive) enzyme, the Lys8-O-Cys38 bridge was absent. However, electron density near the Cys38 sulfur was consistent with molecular oxygen O2. Molecular oxygen was absent in this position in the oxidized (active) enzyme.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Wensien M, von Pappenheim FR, Funk LM, Kloskowski P, Curth U, Diederichsen U, Uranga J, Ye J, Fang P, Pan KT, Urlaub H, Mata RA, Sautner V, Tittmann K. A lysine-cysteine redox switch with an NOS bridge regulates enzyme function. Nature. 2021 May 5. pii: 10.1038/s41586-021-03513-3. doi:, 10.1038/s41586-021-03513-3. PMID:33953398 doi:http://dx.doi.org/10.1038/s41586-021-03513-3
