title: The role of aromatic side-chains in amyloid growth and membrane interaction of the islet amyloid polypeptide fragment LANFLVH.
abstract: Human islet amyloid polypeptide (hIAPP) is known to misfold and aggregate into amyloid deposits that may be found in pancreatic tissues of patients affected by type 2 diabetes. Recent studies have shown that the highly amyloidogenic peptide LANFLVH, corresponding the N-terminal 12-18 region of IAPP, does not induce membrane damage. Here we assess the role played by the aromatic residue Phe in driving both amyloid formation and membrane interaction of LANFLVH. To this aim, a set of variant heptapeptides in which the aromatic residue Phe has been substituted with a Leu and Ala is studied. Differential scanning calorimetry (DSC) and membrane-leakage experiments demonstrated that Phe substitution noticeably affects the peptide-induced changes in the thermotropic properties of the lipid bilayer but not its membrane damaging potential. Atomic force microscopy (AFM), ThT fluorescence and Congo red birefringence assays evidenced that the Phe residue is not required for fibrillogenesis, but it can influence the self-assembling kinetics. Molecular dynamics simulations have paralleled the outcome of the experimental trials also providing informative details about the structure of the different peptide assemblies. These results support a general theory suggesting that aromatic residues, although capable of affecting the self-assembly kinetics of small peptides and peptide-membrane interactions, are not essential either for amyloid formation or membrane leakage, and indicate that other factors such as β-sheet propensity, size and hydrophobicity of the side chain act synergistically to determine peptide properties.
authors.affiliation: Istituto di Biostrutture e Bioimmagini, U.O.S. Catania, Consiglio Nazionale delle Ricerche, Viale Andrea Doria 6, 95125, Catania, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Milardi
authors.forename: Michele F M
authors.initials: MF
authors.lastname: Sciacca
authors.forename: Matteo
authors.initials: M
authors.lastname: Pappalardo
authors.forename: Domenico M
authors.initials: DM
authors.lastname: Grasso
authors.forename: Carmelo
authors.initials: C
authors.lastname: La Rosa
mesh_terms: D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D024322:Amino Acids, Aromatic / Q000737:chemistry* / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D058228:Islet Amyloid Polypeptide / Q000737:chemistry* / Q000378:metabolism; D007930:Leucine / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D018625:Microscopy, Atomic Force; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
chemical_list: D024322:Amino Acids, Aromatic; D058228:Islet Amyloid Polypeptide; D008051:Lipid Bilayers; D010446:Peptide Fragments; D010649:Phenylalanine; D007930:Leucine; D000409:Alanine
references.citation: EMBO J. 2008 Jan 9;27(1):224-33
references.pmid: 18059472
references.citation: Adv Enzymol Relat Areas Mol Biol. 1978;47:45-148
references.pmid: 364941
references.citation: Exp Cell Res. 1989 Aug;183(2):484-93
references.pmid: 2670595
references.citation: Arch Biochem Biophys. 2008 Sep 15;477(2):291-8
references.pmid: 18621014
references.citation: Biochemistry. 1998 Aug 25;37(34):11856-63
references.pmid: 9718308
references.citation: FEBS Lett. 2000 Mar 17;470(1):55-60
references.pmid: 10722845
references.citation: FEBS J. 2006 Aug;273(15):3614-24
references.pmid: 16884500
references.citation: J Mol Biol. 2000 Mar 3;296(4):961-8
references.pmid: 10686095
references.citation: Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5154-9
references.pmid: 12700355
references.citation: Biochemistry. 2008 Dec 2;47(48):12689-97
references.pmid: 18989932
references.citation: J Struct Biol. 2003 Mar;141(3):218-27
references.pmid: 12648568
references.citation: J Mol Biol. 2006 Apr 7;357(4):1306-21
references.pmid: 16483608
references.citation: Biochemistry. 1986 May 6;25(9):2605-12
references.pmid: 3718968
references.citation: Am J Pathol. 1987 Jun;127(3):414-7
references.pmid: 3296768
references.citation: Proc Natl Acad Sci U S A. 2004 Jan 6;101(1):87-92
references.pmid: 14691246
references.citation: J Am Chem Soc. 2009 Jun 17;131(23):8252-61
references.pmid: 19456151
references.citation: Diabetologia. 1987 Nov;30(11):887-92
references.pmid: 3328723
references.citation: J Mol Biol. 2000 Jan 28;295(4):1055-71
references.pmid: 10656810
references.citation: FASEB J. 2002 Jan;16(1):77-83
references.pmid: 11772939
references.citation: Proc Natl Acad Sci U S A. 1987 Jun;84(11):3881-5
references.pmid: 3035556
references.citation: Adv Protein Chem. 1988;39:125-89
references.pmid: 3072867
references.citation: Biochim Biophys Acta. 2007 Sep;1768(9):2026-9
references.pmid: 17662957
references.citation: Science. 1985 Jul 5;229(4708):23-8
references.pmid: 3892686
references.citation: Lancet. 1987 Aug 1;2(8553):231-4
references.pmid: 2441214
references.citation: Proteins. 2003 Aug 1;52(2):176-92
references.pmid: 12833542
references.citation: J Am Chem Soc. 2008 May 21;130(20):6424-9
references.pmid: 18444645
references.citation: J Struct Biol. 2000 Jun;130(2-3):352-62
references.pmid: 10940238
references.citation: J Mol Biol. 2002 Oct 4;322(5):1013-24
references.pmid: 12367525
references.citation: Biochemistry. 2004 Dec 21;43(50):15901-8
references.pmid: 15595845
references.citation: J Mol Biol. 1999 Apr 9;287(4):781-96
references.pmid: 10191146
references.citation: Proteins. 1999 May 1;35(2):133-52
references.pmid: 10223287
references.citation: Nat Struct Biol. 1996 Oct;3(10):842-8
references.pmid: 8836100
references.citation: Biochim Biophys Acta. 1991 Jan 30;1061(2):297-303
references.pmid: 1998698
references.citation: J Chem Phys. 2004 Dec 1;121(21):10748-56
references.pmid: 15549960
references.citation: Curr Med Chem. 2002 Oct;9(19):1725-35
references.pmid: 12369883
references.citation: J Biol Chem. 2001 Sep 7;276(36):34156-61
references.pmid: 11445568
references.citation: J Am Chem Soc. 2010 Jun 16;132(23):8087-97
references.pmid: 20481633
references.citation: J Mol Biol. 2004 Aug 27;341(5):1175-87
references.pmid: 15321714
references.citation: J Mol Biol. 1999 May 7;288(3):477-87
references.pmid: 10329155
references.citation: Cell. 1993 Jun 18;73(6):1055-8
references.pmid: 8513491
references.citation: Biophys J. 2006 Jul 1;91(1):206-16
references.pmid: 16603496
references.citation: Biochim Biophys Acta. 1987 Nov 26;916(2):200-4
references.pmid: 3676331
references.citation: Proc Natl Acad Sci U S A. 2008 Apr 22;105(16):6033-8
references.pmid: 18408164
references.citation: Proc Natl Acad Sci U S A. 1987 Dec;84(23):8628-32
references.pmid: 3317417
references.citation: J Biol Chem. 2002 Sep 20;277(38):35475-80
references.pmid: 12095997
references.citation: J Mol Biol. 1999 Dec 17;294(5):1375-85
references.pmid: 10600392
references.citation: Biochemistry. 2002 Sep 24;41(38):11338-43
references.pmid: 12234175
references.citation: J Mol Biol. 2001 May 4;308(3):515-25
references.pmid: 11327784
references.citation: Nat Biotechnol. 2004 Oct;22(10):1302-6
references.pmid: 15361882
references.citation: Nature. 2003 Aug 14;424(6950):805-8
references.pmid: 12917692
references.citation: Biochem Biophys Res Commun. 1986 Nov 14;140(3):827-31
references.pmid: 3535798
references.citation: Chemistry. 2005 Dec 23;12(2):537-47
references.pmid: 16163753
references.citation: J Am Chem Soc. 2009 May 27;131(20):7079-85
references.pmid: 19405534