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Zinc–Ligand Interactions Modulate Assembly and Stability of the Insulin Hexamer – A Review

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Abstract

Zinc and calcium ions play important roles in the biosynthesis and storage of insulin. Insulin biosynthesis occurs within the β-cells of the pancreas via preproinsulin and proinsulin precursors. In the golgi apparatus, proinsulin is sequestered within Zn2+- and Ca2+-rich storage/secretory vesicles and assembled into a Zn2+ and Ca2+ containing hexameric species, (Zn2+)2(Ca2+)(Proin)6. In the vesicle, (Zn2+)2(Ca2+)(Proin)6 is converted to the insulin hexamer, (Zn2+)2(Ca2+)(In)6, by excision of the C-peptide through the action of proteolytic enzymes. The conversion of (Zn2+)2(Ca2+)(Proin)6to (Zn2+)2(Ca2+)(In)6 significantly lowers the solubility of the hexamer, causing crystallization within the vesicle. The (Zn2+)2(Ca2+)(In)6 hexamer is an allosteric protein that undergoes ligand-mediated interconversion among three global conformation states designated T6, T3R3 and R6. Two classes of allosteric sites have been identified; hydrophobic pockets (3 in T3R3 and 6 in R6) that bind phenolic ligands, and anion sites (1 in T3R3 and 2 in R6) that bind monovalent anions. The allosteric states differ widely with respect to the physical and chemical stability of the insulin subunits. Fusion of the vesicle with the plasma membrane results in the expulsion of the insulin crystals into the intercellular fluid. Dissolution of the crystals, dissociation of the hexamers to monomer and transport of monomers to the liver and other tissues then occurs via the blood stream. Insulin action then follows binding to the insulin receptors. The role of Zn2+ in the assembly, structure, allosteric properties, and dynamic behavior of the insulin hexamer will be discussed in relation to biological function.

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References

  • FM Ashcroft SJH Ashcroft (1992) Insulin Molecular Biology to Pathology Oxford University Press New York 5–92

    Google Scholar 

  • EN Baker TL Blundell JF Cutfield et al. (1988) ArticleTitleThe structure of 2Zn pig insulin crystals at 1.5 Å resolution Phil Trans Roy Soc (London) B 319 369–456

    Google Scholar 

  • FG Banting CH Best (1922) ArticleTitlePancreatic extracts J Lab Clin Med 7 464–472

    Google Scholar 

  • CR Bloom WE Choi PS Brzovic JJ Ha ST Huang NC Kaarsholm MF Dunn (1995) ArticleTitleLigand binding to wild-type and E-B13Q mutant insulins; A three-state allosteric model system showing half-site reactivity J Mol Biol 245 324–330 Occurrence Handle10.1006/jmbi.1994.0027 Occurrence Handle7837266

    Article  PubMed  Google Scholar 

  • CR Bloom R Heymann NC Kaarsholm MF Dunn (1997a) ArticleTitleBinding of 2,6- and 2,7-dihydroxynaphthalene to wild-type and E-B13Q insulins: Dynamic, equilibrium and molecular modeling investigations Biochemistry 36 12746–12758 Occurrence Handle10.1021/bi970761n

    Article  Google Scholar 

  • CR Bloom NC Kaarsholm JJ Ha MF Dunn (1997b) ArticleTitleHalf-site reactivity, negative cooperativity, and positive cooperativity: Quantitative considerations of a plausible model Biochemistry 36 12759–12765 Occurrence Handle10.1021/bi970762f

    Article  Google Scholar 

  • CR Bloom N Wu A Dunn NC Kaarsholm MF Dunn (1998) ArticleTitleComparison of the allosteric properties of the Co(II) and Zn(II) substituted insulin hexamers Biochemistry 37 10937–10944 Occurrence Handle10.1021/bi980071z Occurrence Handle9692986

    Article  PubMed  Google Scholar 

  • T Blundell G Dodson D Hodgkin D Mercola (1972) ArticleTitleInsulin: The structure in the crystal and its reflection in chemistry and biology Adv Protein Chem 26 279–402

    Google Scholar 

  • ML Brader MF Dunn (1991) ArticleTitleInsulin hexamers: New conformations and applications Trends Biochem Sci 16 341–345 Occurrence Handle10.1016/0968-0004(91)90140-Q Occurrence Handle1949156

    Article  PubMed  Google Scholar 

  • ML Brader NC Kaarsholm SE Harnung MF Dunn (1997) ArticleTitleLigand perturbation on a pseudotetrahedral Co(II)(His)3L site. A magnetic circular dichroism study of the Co(II)-substituted insulin hexamer J Biol Chem 272 1088–1094 Occurrence Handle10.1074/jbc.272.2.1088 Occurrence Handle8995407

    Article  PubMed  Google Scholar 

  • ML Brader NC Kaarsholm RW-K Lee MF Dunn (1991) ArticleTitleCharacterization of the R-state insulin hexamer and its derivatives. The hexamer is stabilized by heterotropic ligand binding interactions Biochemistry 30 6636–6645 Occurrence Handle10.1021/bi00241a002 Occurrence Handle2065051

    Article  PubMed  Google Scholar 

  • PS Brzovic WE Choi D Borchardt NC Kaarsholm MF Dunn (1994) ArticleTitleStructural asymmetry and half-site reactivity in the T to R allosteric transition of the insulin hexamer Biochemistry 33 13057–13069 Occurrence Handle10.1021/bi00248a015 Occurrence Handle7947711

    Article  PubMed  Google Scholar 

  • WE Choi ML Brader V Aguilar NC Kaarsholm MF Dunn (1993) ArticleTitleThe allosteric transition of the insulin hexamer is modulated by homotropic and heterotropic interactions Biochemistry 32 11638–11645 Occurrence Handle10.1021/bi00094a021 Occurrence Handle8218231

    Article  PubMed  Google Scholar 

  • E Ciszak GD Smith (1994) ArticleTitleCrystallographic evidence for dual coordination around zinc in the T3R3 human insulin hexamer Biochemistry 33 1512–1517 Occurrence Handle10.1021/bi00172a030 Occurrence Handle8312271

    Article  PubMed  Google Scholar 

  • FD Coffman MF Dunn (1988) ArticleTitleInsulin–metal ion interactions. The binding of divalent cations to insulin hexamers and tetramers and the assembly of insulin hexamers Biochemistry 27 6179–6187 Occurrence Handle10.1021/bi00416a053 Occurrence Handle3056521

    Article  PubMed  Google Scholar 

  • U Derewenda Z Derewenda EJ Dodson et al. (1989) ArticleTitlePhenol stabilizes more helix in a new symmetrical zinc insulin hexamer Nature 338 594–596 Occurrence Handle10.1038/338594a0 Occurrence Handle2648161

    Article  PubMed  Google Scholar 

  • CP Hill Z Dauter EJ Dodson GG Dodson MF Dunn (1991) ArticleTitleX-ray structure of an unusual Ca2+ site and the roles of Zn2+ and Ca2+ in the assembly, stability, and storage of the insulin hexamer Biochemistry 30 919–924

    Google Scholar 

  • SL Howell W Montague M Tyhurst (1975) ArticleTitleCa distribution in islets of Langerhans J Cell Sci 19 395–409 Occurrence Handle172523

    PubMed  Google Scholar 

  • ST Huang WE Choi CR Bloom M Leuenberger MF Dunn (1997) ArticleTitleCarboxylate ions are strong allosteric ligands for the HisB10 sites of the R-state insulin hexamer Biochemistry 36 9878–9888 Occurrence Handle10.1021/bi9701639 Occurrence Handle9245420

    Article  PubMed  Google Scholar 

  • NC Kaarsholm H-C Ko MF Dunn (1989) ArticleTitleComparison of solution structural flexibility and zinc binding domains for insulin, proinsulin and mini-proinsulin Biochemistry 28 4427–4435 Occurrence Handle10.1021/bi00436a046 Occurrence Handle2669954

    Article  PubMed  Google Scholar 

  • W Kadima M Roy RW-K Lee NC Kaarsholm MF Dunn (1992) ArticleTitleMechanisms of stabilization of the insulin hexamer through allosteric ligand interactions J Biol Chem 267 8963–8970 Occurrence Handle1577733

    PubMed  Google Scholar 

  • HB Olsen MR Leuenberger-Fisher W Kadima D Borchardt NC Kaarsholm MF Dunn (2003) ArticleTitleStructural signatures of the complex formed between 3-nitro-4-hydroxybenzoate and the Zn(II)-substituted R6 insulin hexamer Protein Sci 12 1902–1913 Occurrence Handle10.1110/ps.03116403 Occurrence Handle12930990

    Article  PubMed  Google Scholar 

  • S Rahuel-Clermont CA French CI Chou NC Kaarsholm MF Dunn (1997) ArticleTitleMechanisms of stabilization of the insulin hexamer through allosteric ligand interactions Biochemistry 36 5837–5845 Occurrence Handle10.1021/bi963038q Occurrence Handle9153424

    Article  PubMed  Google Scholar 

  • M Roy ML Brader RW-K Lee NC Kaarsholm J Hansen MF Dunn (1989) ArticleTitleSpectroscopic signatures of the T to R conformational transition in the insulin hexamer J Biol Chem 264 19081–19085 Occurrence Handle2681208

    PubMed  Google Scholar 

  • F Seydoux OP Malhotra SA Bernhard (1974) ArticleTitleHalf-site reactivity CRC Crit Rev Biochem 2 227–257 Occurrence Handle4366378

    PubMed  Google Scholar 

  • GD Smith GG Dodson (1992a) ArticleTitleThe structure of a rhombohedral R6 insulin hexamer that binds phenol Biopolymers 32 1749–1756

    Google Scholar 

  • GD Smith GG Dodson (1992b) ArticleTitleStructure of a rhombohedral R6 insulin/phenol complex Proteins: Struct Funct Genet 14 401–408 Occurrence Handle10.1002/prot.340140309

    Article  Google Scholar 

  • GD Smith E Ciszak LA Magrum WA Pangborn RH Blessing (2000) ArticleTitleR6 hexameric insulin complexed with m-cresol or resorcinol Acta Cryst D56 1541–1548

    Google Scholar 

  • MC Storm MF Dunn (1985) ArticleTitleThe Glu(B13) carboxylates of the insulin hexamer form a cage for Cd2+ and Ca2+ ions Biochemistry 24 1749–1756 Occurrence Handle10.1021/bi00328a027 Occurrence Handle2860921

    Article  PubMed  Google Scholar 

  • JL Sudmeier SJ Bell MC Storm MF Dunn (1981) ArticleTitleCadmium-113 nuclear magnetic resonance studies of bovine insulin: Two-zinc insulin hexamer specifically binds calcium Science 212 560–562 Occurrence Handle7010607

    PubMed  Google Scholar 

  • JL Whittingham S Chaudhuri EJ Dodson PCE Moody GG Dodson (1995) ArticleTitleX-ray crystallographic studies on hexameric insulins in the presence of helix-stabilizing agents, thiocyanate, methylparaben, and phenol Biochemistry 34 15553–15563 Occurrence Handle10.1021/bi00047a022 Occurrence Handle7492558

    Article  PubMed  Google Scholar 

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  1. Department of Biochemistry, University of California, 92521, Riverside, CA, USA

    Michael F. Dunn

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  1. Michael F. Dunn
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Correspondence to Michael F. Dunn.

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Dunn, M.F. Zinc–Ligand Interactions Modulate Assembly and Stability of the Insulin Hexamer – A Review. Biometals 18, 295–303 (2005). https://doi.org/10.1007/s10534-005-3685-y

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