title: NMR Structural Studies of Antimicrobial Peptides: LPcin Analogs.
abstract: Lactophoricin (LPcin), a component of proteose peptone (113-135) isolated from bovine milk, is a cationic amphipathic antimicrobial peptide consisting of 23 amino acids. We designed a series of N- or C-terminal truncated variants, mutated analogs, and truncated mutated analogs using peptide-engineering techniques. Then, we selected three LPcin analogs of LPcin-C8 (LPcin-YK1), LPcin-T2WT6W (LPcin-YK2), and LPcin-T2WT6W-C8 (LPcin-YK3), which may have better antimicrobial activities than LPcin, and successfully expressed them in E. coli with high yield. We elucidated the 3D structures and topologies of the three LPcin analogs in membrane environments by conducting NMR structural studies. We investigated the purity of the LPcin analogs and the α-helical secondary structures by performing (1)H-(15)N 2D HSQC and HMQC-NOESY liquid-state NMR spectroscopy using protein-containing micelle samples. We measured the 3D structures and tilt angles in membranes by conducting (15)N 1D and 2D (1)H-(15)N SAMMY type solid-state NMR spectroscopy with an 800 MHz in-house-built (1)H-(15)N double-resonance solid-state NMR probe with a strip-shield coil, using protein-containing large bicelle samples aligned and confirmed by molecular-dynamics simulations. The three LPcin analogs were found to be curved α-helical structures, with tilt angles of 55-75° for normal membrane bilayers, and their enhanced activities may be correlated with these topologies.
authors.affiliation: Department of Chemistry, Hankuk University of Foreign Studies, Yong-In, Korea; Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yong-In, Korea.
authors.forename: Ji-Ho
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Department of Chemistry, Hankuk University of Foreign Studies, Yong-In, Korea; Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yong-In, Korea.
authors.forename: Ji-Sun
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Hankuk University of Foreign Studies, Yong-In, Korea; Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yong-In, Korea.
authors.forename: Sung-Sub
authors.initials: SS
authors.lastname: Choi
authors.affiliation: Department of Chemistry, Hankuk University of Foreign Studies, Yong-In, Korea; Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yong-In, Korea. Electronic address: yakim@hufs.ac.kr.
authors.forename: Yongae
authors.initials: Y
authors.lastname: Kim
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry; D008823:Micelles; D008894:Milk Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D017434:Protein Structure, Tertiary
chemical_list: D000890:Anti-Infective Agents; D008563:Membrane Lipids; D008823:Micelles; D008894:Milk Proteins; D010446:Peptide Fragments; C575429:proteose peptone component 3 (110-135)