Temperature-induced conformational changes in prosomatostatin-II: Implications for processing

Joydeep Mitra, Xue Jun Tang, Steven C. Almo, Dennis Shields

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Somatostatin (SRIF) is a 14-residue peptide hormone synthesized in the hypothalamus and pancreatic islets. SRIF-14 and an N-terminally extended form, SRIF-28, are generated by the proteolytic processing of an approx. 102-residue precursor prosomatostatin (proSRIF) at a single set of paired basic residues (Arg-Lys) and at a monobasic (Arg) site respectively. Previous work in our laboratory demonstrated that the propeptide of SRIF mediates intracellular sorting; we suggested that this information resides in the prohormone structure. To identify putative sorting domains we have investigated structural features of recombinant anglerfish proSRIF-II purified from Escherichia coli. Two species of proSRIF-II were obtained: a monomeric form and a disulphide-linked dimer. CD analyses revealed that monomeric proSRIF-II lacks appreciable periodic secondary structure; however, on slow heating (2°C/min) and cooling, it assumed a predominantly α-helical conformation. When subjected to a second heating-and-cooling cycle, the α-helical conformation was maintained. In contrast, the dimeric form of proSRIF-II was predominantly α-helical and its helicity did not increase in response to heating and recooling. Our results suggest that proSRIF-II might exist in several different folding intermediate states.

Original languageEnglish (US)
Pages (from-to)275-282
Number of pages8
JournalBiochemical Journal
Volume334
Issue number1
DOIs
Publication statusPublished - Aug 15 1998

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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