Loop-inserted and thermostabilized structure of P1-P1' cleaved ovalbumin mutant R339T.


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. Study holds ProTherm entries: 12815 Extra Details: ovalbumin; crystal structure; loop insertion; thermostabilization;,non-inhibitory serpin

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:44 p.m.

Version: 1

Publication Details
Yamasaki M;Arii Y;Mikami B;Hirose M,J. Mol. Biol. (2002) Loop-inserted and thermostabilized structure of P1-P1' cleaved ovalbumin mutant R339T. PMID:11779232
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Ovalbumin P01012 OVAL_CHICK
90.7 Ovalbumin O73860 OVAL_MELGA