Protein Conformational Change Delayed by Steric Hindrance from an N-Linked Glycan
- Authors
- Bager, R., Johansen, J.S., Jensen, J.K., Stensballe, A., Jendroszek, A., Buxbom, L., Sørensen, H.P., and Andreasen, P.A.
- ID
- ZDB-PUB-130703-21
- Date
- 2013
- Source
- Journal of molecular biology 425(16): 2867-77 (Journal)
- Registered Authors
- Keywords
- serpin, PAI-1, glycan, zebrafish, x-ray crystallography
- MeSH Terms
-
- Animals
- Crystallography, X-Ray
- Models, Molecular
- Molecular Sequence Data
- Plasminogen Activator Inhibitor 1/chemistry*
- Plasminogen Activator Inhibitor 1/metabolism*
- Polysaccharides/chemistry*
- Polysaccharides/metabolism*
- Protein Conformation
- Protein Folding*
- Sequence Analysis, DNA
- Zebrafish
- PubMed
- 23702291 Full text @ J. Mol. Biol.
Very few studies have attributed a direct, active, functional role to N-linked glycans. We describe here an N-linked glycan with a unique role for maintaining the active conformation of a protein of the serpin family. The distinguishing feature of serpins is the “stressed-to-relaxed” transition, in which the reactive center loop inserts as a β-strand into the central β-sheet A. This transition forms the basis for the conversion of serpins to the inactive latent state. We demonstrate that plasminogen activator inhibitor-1 (PAI-1) from zebrafish converts to the latent state about 5-fold slower than human PAI-1. In contrast to human PAI-1, fish PAI-1 carries a single N-linked glycan at Asn185 in the gate region through which the reactive center loop passes during latency transition. While the latency transition of human PAI-1 is unaffected by deglycosylation, deglycosylated zebrafish PAI-1 (zfPAI-1) goes latent about 50-fold faster than the glycosylated zfPAI-1 and about 25-fold faster than non-glycosylated human PAI-1. X-ray crystal structure analysis of glycosylated fish PAI-1 confirmed the presence of an N-linked glycan in the gate region and a lack of glycan-induced structural changes. Thus, latency transition of zfPAI-1 is delayed by steric hindrance from the glycan in the gate region. Our findings reveal a previously unknown mechanism for inhibition of protein conformational changes by steric hindrance from N-linked glycans.