title: Single-column purification and bio-characterization of recombinant human parathyroid hormone-related protein (1-139).
abstract: Recombinant human parathyroid hormone-related protein (hPTHrP) (1-139) was expressed using the IMPACT T7 (intein-mediated purification with an affinity chitin-binding tag) system, allowing purification of free recombinant peptide in a single chromatographic step. This system utilizes an intein, which is a protein splicing element from the Saccharomyces cerevisiae VMA1 gene. The intein has been modified so that it undergoes a self-cleavage reaction at its N-terminus at low temperatures in the presence of 1,4-dithiothreitol (DTT). The cDNA encoding hPTHrP (1-139) was cloned into the pTYB1 vector to create an in-frame fusion at the N-terminus of the intein gene. The cDNA for the chitin-binding domain from Bacillus circulans is present at the C-terminus of intein for affinity purification of the three-part fusion protein on a chitin column. The recombinant plasmid was transfected into E. coli ER2566 cells and synthesis of the PTHrP fusion protein was induced with isopropyl-beta-D-thiogalactopyranoside (IPTG). This system produced pure hPTHrP (1-139) and an N-terminally truncated analogue, hPTHrP (27-139), as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blot analysis, N-terminal sequence analysis and mass spectroscopy. hPTHrP (1-139) stimulated cAMP accumulation in ROS 17/2.8 osteoblastic bone cells, whereas hPTHrP (27-139) failed to elicit a response. hPTHrP (1-139) also inhibited the growth of the breast cancer cell line MDA-MB-231; the magnitude of the response was comparable with that of synthetic hPTHrP (1-34) and (1-86). Neutralization of endogenous PTHrP and added hPTHrP (1-139) and N-terminal species with an anti-PTHrP antiserum completely abolished the growth inhibitory effects. These results indicate that the added peptides modulate cell growth by acting at the cell surface. Availability of recombinant hPTHrP (1-139) will allow further study of its biological function, as well as its structure.
authors.affiliation: Department of Pharmacology and Toxicology and Sealy Center for Molecular Science, The University of Texas Medical Branch, Galveston, TX 77555-1031, USA.
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: P K
authors.initials: PK
authors.lastname: Seitz
authors.forename: M
authors.initials: M
authors.lastname: Falzon
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002846:Chromatography, Affinity; D000242:Cyclic AMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D005260:Female; D005822:Genetic Vectors; D006801:Humans; D009363:Neoplasm Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D009363:Neoplasm Proteins; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; D011994:Recombinant Proteins; C432808:parathyroid hormone-related protein (1-139); D000242:Cyclic AMP