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Updated: Nov 17, 2025
Enrichment of Bacterial Lipoproteins and Preparation of N-terminal Lipopeptides for Structural Determination by Mass Spectrometry
Published on: May 21, 2018
Molecular and Functional Characterization of an Anti-lipopolysaccharide Factor Mm-ALF from Speckled Shrimp
Archana K1, Sephy Rose Sebastian1, Sruthy K S1
1Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi, 682016, Kerala, India.
Abstract:
Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides of approximately 100 amino acid residues with a broad spectrum of antimicrobial activity. It is an amphipathic peptide with an N-terminal hydrophobic region and a lipopolysaccharide binding domain (LBD). In the present study, we report an isoform of the anti-lipopolysaccharide factor (Mm-ALF) from the speckled shrimp, Metapenaeus monoceros. A 359 bp cDNA encoded 119 amino acids, and the sequence showed 99.16% similarity to ALF from the shrimp Fenneropenaeus indicus. The mature peptide of 94 amino acids has a net charge of +8, molecular weight 10.62 kDa, and pI 10.11. The mature peptide Mm-ALF was recombinantly expressed in E. coli Rosetta-gami cells, and the peptide was isolated and purified. The rMm-ALF exhibited notable antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Escherichia coli, Edwardsiella tarda, Aeromonas hydrophila, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio proteolyticus, Vibrio cholerae and Vibrio fluvialis) bacteria.
Insights
Researchers identified a novel anti-lipopolysaccharide factor (ALF) from the speckled shrimp Metapenaeus monoceros. This antimicrobial peptide, Mm-ALF, demonstrated significant antibacterial activity against various Gram-positive and Gram-negative bacteria.
Area of Science:
- Marine Biology
- Biochemistry
- Immunology
Background:
- Anti-lipopolysaccharide factors (ALFs) are crucial antimicrobial peptides involved in innate immunity.
- These peptides possess a characteristic amphipathic structure and a lipopolysaccharide binding domain (LBD).
- Understanding novel ALFs can expand knowledge of invertebrate defense mechanisms.
Purpose of the Study:
- To identify and characterize a new anti-lipopolysaccharide factor (ALF) isoform from the speckled shrimp Metapenaeus monoceros.
- To investigate the antimicrobial properties of the recombinant Mm-ALF peptide.
- To contribute to the understanding of shrimp immunity and potential therapeutic applications.
Main Methods:
- cDNA sequencing to identify the Mm-ALF gene.
- Recombinant expression of the mature Mm-ALF peptide in E. coli Rosetta-gami.
- Purification of the recombinant peptide (rMm-ALF).
- In vitro antibacterial assays against a panel of Gram-positive and Gram-negative bacteria.
Main Results:
- A 359 bp cDNA encoding Mm-ALF was identified, showing high similarity to known ALFs.
- The mature Mm-ALF peptide (94 amino acids) was successfully expressed and purified.
- Recombinant Mm-ALF (rMm-ALF) exhibited broad-spectrum antibacterial activity against tested pathogens, including Staphylococcus aureus, Bacillus cereus, and various Vibrio species.
Conclusions:
- The speckled shrimp Metapenaeus monoceros possesses a novel anti-lipopolysaccharide factor, Mm-ALF.
- Recombinant Mm-ALF displays significant antimicrobial efficacy against a range of clinically relevant bacteria.
- Mm-ALF represents a potential candidate for novel antimicrobial strategies.
