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O. been explored as a drug target in and (10). Recent years have seen many new roles being ascribed to Hsp90. In addition to its ability to fold proteins and regulate cell cycle and RG7112 development, recent studies also suggest an ability to guide evolution in eukaryotes (11,C13). The function of Hsp90 as a sensor of environmental cues is especially crucial in protozoan parasites, which often need to respond to radical changes of milieus within and outside their hosts (7, 10). In all organisms investigated to date, Hsp90 proteins are encoded by a RG7112 single open reading frame (ORF), which usually contains multiple introns. In the genome sequence of three isolates, no contiguous ORF was predicted, but two fragments separated by a large stretch of sequence on the same scaffold were detected and RG7112 annotated as and the consequences of this unique genetic rearrangement. We report a post-transcriptional repair mechanism that generates a Hsp90 protein from the two Hsp90 pre-mRNAs. EXPERIMENTAL PROCEDURES Cultivation of Parasites Portland P1 or WB-C6 (assemblage A) parasites were cultured in TYI-S33 (14) supplemented with 12% fetal bovine serum and subcultured with 5 104 cells/tube from log phase parasites. The parasites were harvested by chilling on ice for 20 min followed by repeatedly inverting the tubes to dislodge the parasites and finally pelleted down at 700 for 5 min. PCR and Whole Genome Sequencing Genomic DNA was isolated as described previously (15) with minor modifications. To confirm the position of (200 bp upstream and downstream) gene position was also confirmed from sense primer 5-CCGCATGCTGAGGGTGC-3 and antisense primer 5-CCGTGCAGC-TCTAGCACAATTAC-3. Total RNA was prepared by TRI Reagent (Ambion) according to the manufacturer’s protocol. Five g of total RNA was used for cDNA preparation using oligo(dT) primers (Fermentas cDNA kit). A full-length ORF was amplified with specific primers overlapping the start codon of (ORF 98054 in GiardiaDB) (sense, 5-ATGCCCGCTGAAGTCTTCGAGTTCCAG-3) and (ORF 13864 in GiardiaDB) (antisense, 5-TCAGTCAACTTCGTCAACGTCCTCCTC-3). As an independent determination of the exact site of the transition from the transcript derived from ORF 98054 into that derived from ORF 13864, a PCR fragment from a cDNA template was generated with internal primers HspC-internal (sense, 5-GCGAATTCAGGTCCACGAGCACGTGAAC-3) and HspN-internal (antisense 5-GCGAATTCCTGTGATGTAGTAGATCGAC-3). The resulting 640-bp product was cloned into the EcoRI restriction sites of pBluescript (Stratagene) and sequenced. To rule out the possibility of WB, ATCC 50803). The genome coverage was calculated at 165, and SNPs and InDels were tabulated. Western Blot Analysis Parasites were lysed with 20 mm Tris HCl, pH 6.8, with 1% Triton X-100, and protease inhibitor mixture (G-Biosciences). A high speed supernatant was resolved on a reducing 10% SDS-PAGE gel and blotted to nitrocellulose filters. A rabbit anti-GlHsp90 antibody was raised against a peptide, NKQPALWTRDPKDVTEDE, specific to HspN (Custom Synthesis, Mumbai, India) and was used to probe the filters. In-gel Digestion A narrow slice corresponding to a GlHsp90 band was cut from the stained SDS-PAGE gel and further sliced into smaller gel plugs. After several washes with 100 mm ammonium bicarbonate (NH4HCO3) (Sigma-Aldrich) buffer in 50% acetonitrile (ACN), the gel plugs were subjected to a reduction step using 10 mm dithiothreitol (DTT) (Sigma-Aldrich) in 100 mm NH4HCO3 buffer (45 min at 56 C). Alkylation was performed with a solution of 55 mm iodoacetamide (Sigma-Aldrich) in 100 mm NH4HCO3 (30 min at room temperature in the dark) followed by in-gel digestion with 20 l of trypsin (10 Mouse monoclonal to CD4/CD8 (FITC/PE) ng/l) (Promega) in 50 mm NH4HCO3 (overnight at 37 C). The reaction was stopped by storing at ?20 C, and peptides were extracted in 5% formic acid. Samples were vacuum-dried and reconstituted in 5% formic acid. Mass Spectrometry and Database Searching The protein digest was analyzed by automated nanoflow LC-MS/MS. The sample was loaded onto PepMap C18 reverse phase column connected to a Tempo nano-HPLC system. The peptides were eluted from the analytical column by a linear gradient of 95% Solvent A (98% H2O, 2%.