uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Protein Autoproteolysis: Conformational Strain Linked to the Rate of Peptide Cleavage by the pH Dependence of the N -> O Acyl Shift Reaction
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
Show others and affiliations
2009 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 27, 9475-9477 p.Article in journal (Refereed) Published
Abstract [en]

Nucleophilic attack by a side chain nucleophile on the adjacent peptide bond followed by N -> O or N -> S acyl shift is the primary step in protein autoproteotysis. Precursor structures of autoproteolytic proteins reveal strained (or twisted) amides at the site of cleavage, and we previously showed that SEA domain autoproteotysis involves substrate destabilization by similar to 7 kcal/mol. However, the precise chemical mechanism by which conformational energy is converted into reaction rate acceleration has not been understood. Here we show that the pH dependence of autoproteolysis in a slow-cleaving mutant (115) of the MUC1 SEA domain is consistent with a mechanism in which N -> O acyl shift proceeds after initial protonation of the amide nitrogen. Unstrained amides have pK(a) values of 0 with protonation on the oxygen, and autoproteotysis is therefore immeasurably slow at neutral pH. However, conformational strain forces the peptide nitrogen into a pyramidal conformation with a significantly increased pK(a) for protonation. We find that pK(a) values of similar to 4 and similar to 6, as in model compounds of twisted amides, reproduce the rate of autoproteolysis in the 1G and wild-type SEA domains, respectively. A mechanism involving strain, nitrogen protonation, and N -> O shift is also supported by quantum-chemical calculations. Such a reaction therefore constitutes an alternative to peptide cleavage that is utilized in autoproteolysis, as opposed to a classical mechanism involving a structurally conserved active site with a catalytic triad and an oxyanion hole, which are not present at the SEA domain cleavage site.

Place, publisher, year, edition, pages
2009. Vol. 131, no 27, 9475-9477 p.
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-128356DOI: 10.1021/ja9010817ISI: 000268239400004PubMedID: 19534521OAI: oai:DiVA.org:uu-128356DiVA: diva2:331386
Available from: 2010-07-22 Created: 2010-07-20 Last updated: 2011-03-04Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed
By organisation
Department of Cell and Molecular Biology
In the same journal
Journal of the American Chemical Society
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 196 hits
ReferencesLink to record
Permanent link

Direct link