title: Chaperone characteristics of PDI-related protein A from Aspergillus niger.
abstract: The functional properties of a novel protein, protein disulfide isomerase-related protein A (PRPA) from Aspergillus niger T21, have been characterized. (1) PRPA possesses disulfide isomerase activity. (2) In Hepes buffer, at substoichiometric concentrations, PRPA facilitates the formation of inactive lysozyme aggregates associated with PRPA (anti-chaperone activity); while at a high molar excess, PRPA inhibits aggregation by maintaining lysozyme in a soluble, yet inactive, state (chaperone-like activity). However, PRPA only exhibits chaperone-like activity during lysozyme refolding in phosphate buffer. (3) Experiments have indicated that disulfide cross-linkage is not required for the interaction between PRPA and lysozyme, and hydrophobic interaction may be responsible for PRPA effect on lysozyme. (4) Co-expression of PRPA and prochymosin in Escherichia coli leads to reduction of inclusion bodies, rendering part of prochymosin molecules soluble yet inactive. The structural and functional characteristics of PRPA suggest that PRPA may play an important role in protein folding, aggregation, and retention in the endoplasmic reticulum.
authors.affiliation: Institute of Microbiology, Chinese Academe of Sciences, Beijing 100080, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Zhou
authors.forename: Yuying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Cuijuan
authors.initials: C
authors.lastname: Jia
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Yang
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D012085:Chymosin / Q000235:genetics; D003001:Cloning, Molecular; D004792:Enzyme Precursors / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D018832:Molecular Chaperones / Q000378:metabolism*; D009113:Muramidase / Q000378:metabolism; D011489:Protein Denaturation; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D004792:Enzyme Precursors; D005656:Fungal Proteins; D018832:Molecular Chaperones; C404324:PRPA protein, Aspergillus niger; D011994:Recombinant Proteins; D009113:Muramidase; C032443:prorennin; D012085:Chymosin; D019704:Protein Disulfide-Isomerases