The Acidic C-terminal Domain Stabilizes the Chaperone Function of Protein Disulfide Isomerase

• Published in: The Journal of biological chemistry 2004-11, Vol.279 (47), p.48830-48835
• Main Authors: Tian, Rui, Li, Sheng-Jian, Wang, Dong-Liang, Zhao, Zhen, Liu, Ying, He, Rong-Qiao
• Format: Article
• Language: English
• Subjects: Catalysis; DNA, Complementary - metabolism; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Guanidine - chemistry; Hot Temperature; Humans; Kinetics; L-Lactate Dehydrogenase - chemistry; Light; Models, Chemical; Molecular Chaperones - chemistry; Mutation; Protein Conformation; Protein Disulfide-Isomerases - chemistry; Protein Disulfide-Isomerases - genetics; Protein Folding; Protein Structure, Tertiary; Scattering, Radiation; Temperature; Time Factors
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M407076200

Protein disulfide isomerase (PDI, EC 5.3.4.1) is a chaperone and catalyzes the formation and rearrangement of disulfide bonds in proteins. Domain c-(463–491), containing 18 acidic residues, is an interesting and important C-terminal extension of PDI. In this study, the PDI mutant abb′a′, in which domain c is truncated, was used to investigate the relationship between the C-terminal structure and chaperone function. Reactivation and light-scattering experiments show that both wild-type PDI and abb′a′ interact with lactate dehydrogenase (LDH, EC 1.1.1.27), which tends to self-aggregate during reactivation. The interaction enhances reactivation of LDH and reduces aggregation. According to these results, it seems as if domain c might be dispensable to the chaperone function of PDI. However, abb′a′ is prone to self-aggregation and causes increased aggregation of LDH during thermal denaturation. In contrast, wild-type PDI remains active as a chaperone under these conditions and prevents self-aggregation of LDH. Furthermore, measurements of intrinsic fluorescence and difference absorbance during denaturation show that abb′a′ is much more labile to heat or guanidine hydrochloride denaturation than wild-type PDI. This suggests that domain c is required for the stabilization and maintenance of the chaperone function of PDI under extreme conditions.