The acidic C-terminal domain stabilizes the chaperone function of protein disulfide isomerase.
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.
Tian
Rui
R
Laboratory of Visual Information Processing, Chinese Academy of Sciences, Beijing, China.
Li
Sheng-Jian
SJ
Wang
Dong-Liang
DL
Zhao
Zhen
Z
Liu
Ying
Y
He
Rong-Qiao
RQ
D002384:Catalysis; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D019791:Guanidine / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000737:chemistry; D008027:Light; D008956:Models, Chemical; D018832:Molecular Chaperones / Q000737:chemistry; D009154:Mutation; D011487:Protein Conformation; D019704:Protein Disulfide-Isomerases / Q000737:chemistry* / Q000235:genetics; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D013696:Temperature; D013997:Time Factors
D018076:DNA, Complementary; D018832:Molecular Chaperones; D007770:L-Lactate Dehydrogenase; D019704:Protein Disulfide-Isomerases; D019791:Guanidine