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bioRxiv · 10.1101/307702

Novel anionic cecropins from the spruce budworm feature a poly-L-aspartic acid C-terminus

maaroufi, H.·Cusson, M.·Levesque, R. C.
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Abstract

Cecropins form a family of amphipathic -helical cationic peptides with broad-spectrum antibacterial properties and potent anticancer activity. The emergence of bacteria and cancer cells showing resistance to cationic antimicrobial peptides (CAMPs) has fostered a search for new, more selective and more effective alternatives to CAMPs. With this goal in mind, we looked for cecropin homologs in the genome and transcriptome of the spruce budworm, Choristoneura fumiferana. Not only did we find paralogs of the conventional cationic cecropins (Cfcec+), our screening also led to the identification of previously uncharacterized anionic cecropins (Cfcec-), featuring a poly-L-aspartic acid C-terminus. Comparative peptide analysis indicated that the C-terminal helix of Cfcec- is amphipathic, unlike that of Cfcec+, which is hydrophobic. Interestingly, molecular dynamics simulations pointed to the lower conformational flexibility of Cfcec- peptides, relative to that of Cfcec+. Phylogenetic analysis suggests that the evolution of distinct Cfcec+ and Cfcec- peptides may have resulted from an ancient duplication event within the Lepidoptera. Our analyses also indicated that Cfcec- shares characteristics with entericidins, which are involved in bacterial programmed cell death, lunasin, a peptide of plant origins with antimitotic effects, and APC15, a subunit of the anaphase-promoting complex. Finally, we found that both anionic and cationic cecropins contain a BH3-like motif (G-[KQR]-[HKQNR]-[IV]-[KQR]) that could interact with Bcl-2, a protein involved in apoptosis; this observation is congruent with previous reports indicating that cecropins induce apoptosis. Altogether, our observations suggest that cecropins may provide templates for the development of new anticancer drugs. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=70 SRC="FIGDIR/small/307702v2_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@ba988dorg.highwire.dtl.DTLVardef@757d76org.highwire.dtl.DTLVardef@18009b5org.highwire.dtl.DTLVardef@fd71d3_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIGenes encoding novel anionic cecropins (Cfcec-), featuring a C-terminal poly-L-aspartic acid, were found in the genome of the spruce budworm, Choristoneura fumiferana. C_LIO_LIDivergence between Cfcec+ and Cfcec- could be the result of an ancient duplication event within the Lepidoptera. C_LIO_LIThere is an apparent relationship between motifs observed in cecropin peptides and apoptosis. C_LIO_LIAnionic cecropins from the spruce budworm display characteristics suggesting they could have anticancer activity C_LI

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maaroufi, H., Cusson, M., Levesque, R. C.. 2018-04-25. Novel anionic cecropins from the spruce budworm feature a poly-L-aspartic acid C-terminus. https://doi.org/10.1101/307702

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