title: Solution structure, antibacterial activity, and expression profile of Manduca sexta moricin.
abstract: In response to wounding or infection, insects produce a battery of antimicrobial peptides (AMPs) and other defense molecules to kill the invading pathogens. To study their structures, functions, and transcriptional regulation, we synthesized Manduca sexta moricin, a 42-residue peptide (GKIPVKAIKQAGKVIGKGLRAINIAGTTHDVVSFFRPKKKKH, 4539 Da). The compound exhibited potent antimicrobial activities against a broad spectrum of Gram-positive and Gram-negative bacteria with a minimum inhibitory concentration of 1.4 microM. The mRNA levels of M. sexta moricin increased substantially in fat body and hemocytes after the larvae were challenged with bacterial cells. We determined the solution structure of this AMP by two-dimensional 1H-1H -nuclear magnetic resonance spectroscopy. The tertiary structure is composed of an eight-turn alpha-helix spanning almost the entire peptide. Insights of relationships between the structure and function are also presented.
authors.affiliation: Department of Biochemistry, Kansas State University, USA.
authors.forename: Huaien
authors.initials: H
authors.lastname: Dai
authors.forename: Subrahmanyam
authors.initials: S
authors.lastname: Rayaprolu
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Gong
authors.forename: Rudan
authors.initials: R
authors.lastname: Huang
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Haobo
authors.initials: H
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D002942:Circular Dichroism; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D019476:Insect Proteins / Q000737:chemistry* / Q000494:pharmacology*; D018402:Manduca / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009928:Organ Specificity; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; C097209:moricin protein, Bombyx mori