PMID:17697113

Citation	Wang, ZQ, Han, YH, Shao, XX, Chi, CW and Guo, ZY (2007) Molecular cloning, expression and characterization of protein disulfide isomerase from Conus marmoreus. FEBS J. 274:4778-87
Abstract	The oxidative folding of disulfide-rich conotoxins is essential for their biological functions. In vivo, disulfide bond formation is mainly catalyzed by protein disulfide isomerase. To elucidate the physiologic roles of protein disulfide isomerase in the folding of conotoxins, we have cloned a novel full-length protein disulfide isomerase from Conus marmoreus. Its ORF encodes a 500 amino acid protein that shares sequence homology with protein disulfide isomerases from other species, and 70% homology with human protein disulfide isomerase. Enzymatic analyses of recombinant C. marmoreus protein disulfide isomerase showed that it shared functional similarities with human protein disulfide isomerase. Using conotoxins tx3a and sTx3.1 as substrate, we analyzed the oxidase and isomerase activities of the C. marmoreus protein disulfide isomerase and found that it was much more efficient than glutathione in catalyzing oxidative folding and disulfide isomerization of conotoxins. We further demonstrated that macromolecular crowding had little effect on the protein disulfide isomerase-catalyzed oxidative folding and disulfide isomerization of conotoxins. On the basis of these data, we propose that the C. marmoreus protein disulfide isomerase plays a key role during in vivo folding of conotoxins.
Links	PubMed Online version:10.1111/j.1742-4658.2007.06003.x
Keywords	Amino Acid Sequence; Animals; Catalysis; Cloning, Molecular; Conotoxins/chemistry; Conotoxins/metabolism; Conus Snail/enzymology; Conus Snail/genetics; Disulfides/chemistry; Disulfides/metabolism; Evolution, Molecular; Humans; Isomerism; Molecular Sequence Data; Muramidase/chemistry; Muramidase/metabolism; Oxidation-Reduction; Protein Disulfide-Isomerases/biosynthesis; Protein Disulfide-Isomerases/chemistry; Protein Disulfide-Isomerases/genetics; Protein Disulfide-Isomerases/metabolism; Protein Folding; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CONMR:Q1HGL1		GO:1903332: regulation of protein folding	ECO:0000314:		P		Figure 2 shows the effect of cPDI on lyzozyme refolding. At low doses, it reduces the refolding yield, but at high doses it increases the refolding yield.	complete CACAO 10913
CONMR:Q1HGL1		GO:0015035: protein disulfide oxidoreductase activity	ECO:0000314:		F		Figure 4 shows the oxidation of reduced, linear tx3a in the presence of cPDI. As time progresses, the peak for the reduced form disappears and the peak for oxidized, folded tx3a appears. Panel B shows that this occurs faster with higher amounts of cPDI.	complete CACAO 10914
CONMR:Q1HGL1		GO:0016853: isomerase activity	ECO:0000314:		F		Figure 6 shows the isomerization of one major refolding product of reduced Tx3.1, sTx3.1, to the normal refolding product, nTx3.1, by cPDI. As time progresses, the percentage of nTx3.1 protein increases in the presence of cPDI in a dose-dependent manner	complete CACAO 10915
CONMR:Q1HGL1	enables	GO:0015035: protein disulfide oxidoreductase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
CONMR:Q1HGL1	enables	GO:0016853: isomerase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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