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Updated: Jul 7, 2026

Rearing and Injection of Manduca sexta Larvae to Assess Bacterial Virulence
Published on: December 11, 2012
Solution structure, antibacterial activity, and expression profile of Manduca sexta moricin
Huaien Dai1, Subrahmanyam Rayaprolu, Yuxi Gong
1Department of Biochemistry, Kansas State University, USA.
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.
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