title: An atypical protein disulfide isomerase from the protozoan parasite Leishmania containing a single thioredoxin-like domain.
abstract: In higher eukaryotes, secretory proteins are under the quality control of the endoplasmic reticulum for their proper folding and release into the secretory pathway. One of the proteins involved in the quality control is protein disulfide isomerase, which catalyzes the formation of protein disulfide bonds. As a first step toward understanding the endoplasmic reticulum quality control of secretory proteins in lower eukaryotes, we have isolated a protein disulfide isomerase gene from the protozoan parasite Leishmania donovani. The parasite enzyme shows high sequence homology with homologs from other organisms. However, unlike the four thioredoxin-like domains found in most protein disulfide isomerases, of which two contain an active site, the leishmanial enzyme possesses only one active site present in a single thioredoxin-like domain. When expressed in Escherichia coli, the recombinant parasite enzyme shows both oxidase and isomerase activities. Replacement of the two cysteins with alanines in its active site results in loss of both enzymatic activities. Further, overexpression of the mutated/inactive form of the parasite enzyme in L. donovani significantly reduced their release of secretory acid phosphatases, suggesting that this single thioredoxin-like domain protein disulfide isomerase could play a critical role in the Leishmania secretory pathway.
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Padilla
authors.forename: Robert
authors.initials: R
authors.lastname: Noiva
authors.forename: Nancy
authors.initials: N
authors.lastname: Lee
authors.forename: Ketha V Krishna
authors.initials: KV
authors.lastname: Mohan
authors.forename: Hira L
authors.initials: HL
authors.lastname: Nakhasi
authors.forename: Alain
authors.initials: A
authors.lastname: Debrabant
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007893:Leishmania donovani / Q000201:enzymology*; D008969:Molecular Sequence Data; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D013879:Thioredoxins; D019704:Protein Disulfide-Isomerases