title: Molecular structure of RADA16-I designer self-assembling peptide nanofibers.
abstract: The designer self-assembling peptide RADA16-I forms nanofiber matrices which have shown great promise for regenerative medicine and three-dimensional cell culture. The RADA16-I amino acid sequence has a β-strand-promoting alternating hydrophobic/charged motif, but arrangement of β-strands into the nanofiber structure has not been previously determined. Here we present a structural model of RADA16-I nanofibers, based on solid-state NMR measurements on samples with different schemes for (13)C isotopic labeling. NMR peak positions and line widths indicate an ordered structure composed of β-strands. The NMR data show that the nanofibers are composed of two stacked β-sheets stabilized by a hydrophobic core formed by alanine side chains, consistent with previous proposals. However, the previously proposed antiparallel β-sheet structure is ruled out by measured (13)C-(13)C dipolar couplings. Instead, neighboring β-strands within β-sheets are parallel, with a registry shift that allows cross-strand staggering of oppositely charged arginine and aspartate side chains. The resulting structural model is compared to nanofiber dimensions observed via images taken by transmission electron microscopy and atomic force microscopy. Multiple NMR peaks for each alanine side chain were observed and could be attributed to multiple configurations of side chain packing within a single scheme for intermolecular packing.
authors: Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering , 2525 Pottsdamer Street, Tallahassee, Florida 32310-6046, United States.
authors: Ashley R
authors: AR
authors: Cormier
authors: Xiaodong
authors: X
authors: Pang
authors: Maxwell I
authors: MI
authors: Zimmerman
authors: Huan-Xiang
authors: HX
authors: Zhou
authors: Anant K
authors: AK
authors: Paravastu
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D015195:Drug Design; D008422:Materials Testing; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000648:ultrastructure; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure*; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D046912:Multiprotein Complexes; D010455:Peptides; C546681:RADA16-I
references: Proc Natl Acad Sci U S A. 2006 Mar 28;103(13):5054-9
references: 16549776
references: Int J Mol Sci. 2009 May 14;10(5):2136-45
references: 19564944
references: Nature. 2007 May 24;447(7143):453-7
references: 17468747
references: Macromol Biosci. 2010 Jan 11;10(1):33-9
references: 19705375
references: Angew Chem Int Ed Engl. 2009;48(12):2118-21
references: 19130518
references: Biochemistry. 2005 Aug 9;44(31):10669-80
references: 16060675
references: Biochemistry. 2010 Nov 9;49(44):9457-69
references: 20695483
references: Curr Biol. 1993 May 1;3(5):249-53
references: 15335744
references: J Am Chem Soc. 2011 Mar 23;133(11):4018-29
references: 21355554
references: Proc Natl Acad Sci U S A. 1993 Apr 15;90(8):3334-8
references: 7682699
references: Adv Mater. 2009 Sep 4;21(32-33):3246-54
references: 20882495
references: Proc Natl Acad Sci U S A. 2005 Jun 14;102(24):8414-9
references: 15939888
references: Prog Nucl Magn Reson Spectrosc. 2011 Feb;58(1-2):62-87
references: 21241884
references: J Magn Reson. 2006 Feb;178(2):248-82
references: 16338152
references: Biochemistry. 2011 Mar 29;50(12):2026-39
references: 21291268
references: J Am Chem Soc. 2002 Dec 18;124(50):15030-7
references: 12475347
references: Nucleic Acids Res. 2008 Jan;36(Database issue):D402-8
references: 17984079
references: J Biomol NMR. 1999 Mar;13(3):289-302
references: 10212987
references: J Phys Chem B. 2009 Jan 15;113(2):531-5
references: 19132862
references: J Mol Biol. 1999 Oct 15;293(1):151-60
references: 10512723
references: PLoS One. 2010 Mar 10;5(3):e9642
references: 20224794
references: Int J Nanomedicine. 2011;6:943-55
references: 21720506
references: J Pept Sci. 2008 Feb;14(2):152-62
references: 18196533
references: EMBO J. 1992 Oct;11(10):3787-96
references: 1396572
references: Biophys J. 2002 Aug;83(2):1205-16
references: 12124300
references: Trends Biotechnol. 2002 Jan;20(1):16-21
references: 11742673
references: Angew Chem Int Ed Engl. 2008;47(31):5842-5
references: 18528917
references: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6728-33
references: 10841570
references: Nanomedicine (Lond). 2011 Nov;6(9):1621-43
references: 22077465
references: Biotechnol Adv. 2002 Dec;20(5-6):321-39
references: 14550019
references: Proc Natl Acad Sci U S A. 2007 May 8;104(19):7791-6
references: 17470802
references: Biomacromolecules. 2013 May 13;14(5):1370-8
references: 23480446
references: PLoS One. 2011;6(5):e19782
references: 21611127
references: Biophys J. 2012 Apr 4;102(7):1617-26
references: 22500762
references: Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2011 Nov-Dec;3(6):589-606
references: 21780306
references: Biochem J. 2009 Jul 15;421(3):415-23
references: 19435461
references: J Chem Phys. 2007 Feb 14;126(6):064506
references: 17313228
references: J Mol Biol. 2004 Jan 2;335(1):247-60
references: 14659754
references: Q Rev Biophys. 2006 Feb;39(1):1-55
references: 16772049
references: Arch Biochem Biophys. 2008 Jan 1;469(1):4-19
references: 17585870
references: Biomacromolecules. 2012 Jun 11;13(6):1794-804
references: 22559149
references: Macromol Biosci. 2007 May 10;7(5):544-51
references: 17477441
references: PLoS One. 2010 Apr 22;5(4):e10305
references: 20421985
references: Biotechnol Adv. 2012 May-Jun;30(3):593-603
references: 22041166
references: Proc Natl Acad Sci U S A. 2009 Mar 24;106(12):4623-8
references: 19273853
references: J Am Chem Soc. 2007 Apr 25;129(16):5117-30
references: 17397156
references: PLoS One. 2007 Feb 07;2(2):e190
references: 17285144
references: Biomaterials. 1995 Dec;16(18):1385-93
references: 8590765
references: J Chem Phys. 2011 Aug 7;135(5):055102
references: 21823733
references: Proc Natl Acad Sci U S A. 1994 Jun 7;91(12):5355-8
references: 8202492
references: Proc Natl Acad Sci U S A. 2008 Nov 25;105(47):18349-54
references: 19015532
references: Protein Sci. 2000 Jun;9(6):1095-105
references: 10892803