1JTI

Loop-inserted Structure of P1-P1' Cleaved Ovalbumin Mutant R339T

Summary for 1JTI

• Entry DOI: 10.2210/pdb1jti/pdb
• Descriptor: Ovalbumin (2 entities in total)
• Functional Keywords: ovalbumin, loop insertion, non-inhibitory serpin, allergen
• Biological source: Gallus gallus (chicken)
• Cellular location: Secreted: P01012
• Total number of polymer chains: 2
• Total formula weight: 85531.70

Authors

Yamasaki, M.,Arii, Y.,Mikami, B.,Hirose, M. (deposition date: 2001-08-21, release date: 2001-09-05, Last modification date: 2024-10-30)

Primary citation

Yamasaki, M.,Arii, Y.,Mikami, B.,Hirose, M.
Loop-inserted and thermostabilized structure of P1-P1' cleaved ovalbumin mutant R339T.
J.Mol.Biol., 315:113-120, 2002

PubMed Abstract: Ovalbumin is a member of a superfamily of serine proteinase inhibitors, known as the serpins. It is, however, non-inhibitory towards serine proteinases, and lacks the loop insertion mechanism common to the serpins due to unknown structural factors. Mutant ovalbumin, R339T, in which the P14 hinge residue is replaced, was produced and analyzed for its thermostability and three-dimensional structure. Differential scanning calorimetry revealed that the mutant ovalbumin, but not the wild-type protein, undergoes a marked thermostabilization (DeltaT(m)=15.8 degrees C) following the P1-P1' cleavage. Furthermore, the crystal structure, solved at 2.3 A resolution, clearly proved that the P1-P1' cleaved form assumes the fully loop-inserted conformation as seen in serpin that possess inhibitory activity. We therefore conclude that ovalbumin acquires the structural transition mechanism into the loop-inserted, thermostabilized form by the single hinge mutation. The mutant protein does not, however, possess inhibitory activity. The solved structure displays the occurrence of specific interactions that may prevent the smooth motion, relative to sheet A, of helices E and F and of the loop that follows helix F. These observations provide crucial insights into the question why R339T is still non-inhibitory.

PubMed: 11779232
DOI: 10.1006/jmbi.2001.5056

Experimental method

X-RAY DIFFRACTION (2.3 Å)