Annular Arrangement and Collaborative Actions of Four Domains of Protein-disulfide Isomerase - Analytical Methods & Tools for Lyophilization

Annular Arrangement and Collaborative Actions of Four Domains of Protein-disulfide Isomerase
Received for publication, August 1, 2005 , and in revised form, December 28, 2005.
Originally published In Press as doi:10.1074/jbc.M508422200 on December 29, 2005
Sheng-jian Li1, Xin-guo Hong?1, Yuan-yuan Shi, Hui Li||, and Chih-chen Wang2
J. Biol. Chem., Vol. 281, Issue 10, 6581-6588, March 10, 2006

A SMALL ANGLE X-RAY SCATTERING STUDY IN SOLUTION*
From the National Laboratory of Biomacromolecules and the ||Center for System Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, the ?Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, and the Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
We presented for the first time a small angle x-ray scattering study of intact protein-disulfide isomerase (PDI) in solution. The restored model revealed that PDI is a short and roughly elliptical cylinder with a molecular mass of 69 kDa and dimensions of 105 x 65 x 40 ?, and the four thioredoxin-fold domains in the order a-b-b'-a' are arranged in an annular fashion. Atomic force microscope imaging also supported the finding that PDI appears as an approximately flat elliptical cylinder. A PDI species with apparent molecular mass of 116 kDa measured by using size-exclusion chromatography, previously assumed to be a dimer, was determined to exist mainly as a monomer by using analytical ultracentrifugation. The C-terminal fragment 441?491 contributed to the anomalous molecular mass determination of PDI by size-exclusion chromatography. The annular model of PDI accounted for the cooperative properties of the four domains in both the isomerase and chaperone functions of PDI.
* This work was supported by Grants 2004CB520801 and 2006CB500703 from the Chinese Ministry of Science and Technology, Grants KSCX2-SW214-2 and KJCX2-SW-N06 from the Chinese Academy of Sciences, and Grant 10375075 from the Chinese Natural Science Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 Both authors contributed equally to this work.
2 To whom correspondence should be addressed: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd., Beijing 100101, China. Tel.: 86-10-64888502; Fax: 86-10-64872026; E-mail: chihwang@sun5.ibp.ac.cn.
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