Solution structure of proinsulin: Connecting domain flexibility and prohormone processing

Yanwu Yang, Qing Xin Hua, Jin Liu, Eri H. Shimizu, Meredith H. Choquette, Robert B. Mackin, Michael A. Weiss

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

The folding of proinsulin, the single-chain precursor of insulin, ensures native disulfide pairing in pancreatic β-cells. Mutations that impair folding cause neonatal diabetes mellitus. Although the classical structure of insulin is well established, proinsulin is refractory to crystallization. Here, we employ heteronuclear NMR spectroscopy to characterize a monomeric analogue. Proinsulin contains a native-like insulin moiety (A- and B-domains); the tethered connecting (C) domain (as probed by {1H}-15N nuclear Overhauser enhancements) is progressively less ordered. Although the BC junction is flexible, residues near the CA junction exhibit α-helical-like features. Relative to canonical α-helices, however, segmental 13Cα/β chemical shifts are attenuated, suggesting that this junction and contiguous A-chain residues are molten. We propose that flexibility at each C-domain junction facilitates prohormone processing. Studies of protease SPC3 (PC1/3) suggest that C-domain sequences contribute to cleavage site selection. The structure of proinsulin provides a foundation for studies of insulin biosynthesis and its impairment in monogenic forms of diabetes mellitus.

Original languageEnglish (US)
Pages (from-to)7847-7851
Number of pages5
JournalJournal of Biological Chemistry
Volume285
Issue number11
DOIs
StatePublished - Mar 12 2010

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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