Strand 6B deformation and residues exposure towards N-terminal end of helix B during proteinase inhibition by Serpins.
Bioinformation 2011;
5:315-9. [PMID:
21383917 PMCID:
PMC3046034 DOI:
10.6026/97320630005315]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 10/26/2010] [Indexed: 11/30/2022] Open
Abstract
Serine Protease inhibitors (Serpins) like antithrombin, antitrypsin, neuroserpin, antichymotrypsin, protein C-inhibitor and plasminogen activator inhibitor
is involved in important biological functions like blood coagulation, fibrinolysis, inflammation, cell migration and complement activation. Serpins native
state is metastable, which undergoes transformation to a more stable state during the process of protease inhibition. Serpins are prone to conformation
defects, however little is known about the factors and mechanisms which promote its conformational change and misfolding. Helix B region in serpins is
with several point mutations which result in pathological conditions due to polymerization. Helix B analysis for residue burial and cavity was undertaken
to understand its role in serpin structure function. A structural overlap and an accessible surface area analysis showed the deformation of strand 6B and
exposure of helix B at N-terminal end in cleaved conformation but not in the native and latent conformation of various inhibitory serpins. A cleaved
polymer like conformation of antitrypsin also showed deformation of s6B and helix B exposure. Cavity analysis showed that helix B residues were part of
the largest cavity in most of the serpins in the native state which increase in size during the transformation to cleaved and latent states. These data for the
first time show the importance of strand 6B deformation and exposure of helix B in smooth insertion of the reactive center loop during serpin inhibition
and indicate that helix B exposure due to variants may increase its polymer propensity.
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