Abstract
Cecropins form a family of amphipathic α-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.
Highlights
Genes encoding novel anionic cecropins (Cfcec-), featuring a C-terminal poly-L-aspartic acid, were found in the genome of the spruce budworm, Choristoneura fumiferana.
Divergence between Cfcec+ and Cfcec- could be the result of an ancient duplication event within the Lepidoptera.
There is an apparent relationship between motifs observed in cecropin peptides and apoptosis.
Anionic cecropins from the spruce budworm display characteristics suggesting they could have anticancer activity
- Abbreviations
- Cfcec+
- C. fumiferana cationic cecropins
- Cfcec-
- C. fumiferana anionic cecropins
- PAA
- C-terminal poly-L-aspartic acid
- AMPs
- antimicrobial peptides
- CAMPs
- cationic antimicrobial peptides
- ACPs
- anticancer-peptides
- APD
- Antimicrobial Peptide Database
- LPS
- lipopolysaccharides
- Pxcec+
- cationic Papilio Xuthus cecropi
- HccecA
- H. cecropina cecropin-A
- Pxcec-
- anionic P. Xuthus cecropin
- CED-9
- cell-death abnormal 9
- Bcl-2
- B-cell lymphoma 2
- APC15
- subunit anaphase-promoting complex 15
- MCC
- the mitotic checkpoint complex
- SAC
- spindle assembly checkpoint
- hepG-2
- human liver hepatocellular carcinoma cell line