Antimicrobial and structural insights of a new snakin-like peptide isolated from Peltophorum dubium (Fabaceae)

Abstract

Snakins are antimicrobial peptides (AMPs) found, so far, exclusively in plants, and known to be important in the defense against a wide range of pathogens. Like other plant AMPs, they contain several positively charged amino acids, and an even number of cysteine residues forming disulfide bridges which are considered important for their usual function. Despite its importance, studies on snakin tertiary structure and mode of action are still scarce. In this study, a new snakin-like gene was isolated from the native plant Peltophorum dubium, and its expression was verified in seedlings and adult leaves. The deduced peptide (PdSN1) shows 84% sequence identity with potato snakin-1 mature peptide, with the 12 cysteines characteristic from this peptide family at the GASA domain. The mature PdSN1 coding sequence was successfully expressed in Escherichia coli. The purified recombinant peptide inhibits the growth of important plant and human pathogens, like the economically relevant potato pathogen Streptomyces scabies and the opportunistic fungi Candida albicans and Aspergillus niger. Finally, homology and ab initio modeling techniques coupled to extensive molecular dynamics simulations were used to gain insight on the 3D structure of PdSN1, which exhibited a helix-turn-helix motif conserved in both native and recombinant peptides. We found this motif to be strongly coded in the sequence of PdSN1, as it is stable under different patterns of disulfide bonds connectivity, and even when the 12 cysteines are considered in their reduced form, explaining the previous experimental evidences.

Antibacterial potential of Antimicrobial peptides containing whole proteins of two Adiantum species from Himalaya against selected human bacterial pathogens

“…Other research groups also studies the effect of antimicrobial proteins and pep-tides extracted from other plants sources on human pathogenic bacteria, including the three; S. aureus, P. aeruginosa and E. coli. Like our observations, crude proteins isolated from Allium cepa (Garlic) and Peltophorum dubium were also more effective against S. aureus and P. aeruginosa compared to E. coli (Gao et al, 2019;Rodríguez-Decuadro et al, 2018). Even for peptides being expressed in gene expression system, the crude proteins were more effective against S.aureus (25% growth reduction) than E. coli (20% growth reduction) as bactericidal agent (Chahardoli et al, 2018;Mandal et al, 2009) also reported similar pattern of antibiotic potential against S. aureus, P. aeruginosa and E. coli, using partially puri ied antimicrobial peptides peak from Green coconut water proteins extract.…”

“…Puri ied peptides from Spirulina platensis, a cyanobacteria, were found more microbicidal against E. coli (MIC 8mg/ml) than S. aureus (16mg/ml) (Sun et al, 2016). Although, the indings of (Rodríguez-Decuadro et al, 2018) were opposite to it. They found that same concentration (14.4µg/ml) of puri ied peptides from Peltophorum dubium was inhibiting 56% growth of S. aureus but unable to inhibit growth of E. coli.…”

Reassessing the Host Defense Peptide Landscape

“…In fact, the vast majority of studies related to AMPs have sought to identify and characterize peptides with potent and broad spectrum antimicrobial properties. Common strategies involve searching for novel peptides from natural sources either through the analysis of increasingly-exotic biological organisms and tissue extracts (Kim et al, 2018), identifying potential AMP sequences from genomic sequence information (Rodríguez-Decuadro et al, 2018; Yang et al, 2018), or excising predicted antimicrobial sequences from larger proteins (Pane et al, 2016; Abdillahi et al, 2018). Furthermore, a large portion of the relevant scientific literature is devoted to studies aimed at selectively enhancing the antibacterial potency of synthetic peptides either by systematically altering the amino acid composition of natural AMPs (Akbari et al, 2018; Chen et al, 2018) or designing novel sequences based on the structural and biophysical properties of known AMPs (Haney and Hancock, 2013; Kumar et al, 2018).…”

Genome-Wide Comprehensive Analysis of the GASA Gene Family in Populus

“…Likewise, the allogenic expression of StSN1 could improve the tolerance to fungal pathogens in transgenic lettuce plants [13]. PdSN1, the homologous protein of potato snakin-1 in Peltophorum dubium, inhibited the growth of multiple plants and animal pathogens in vitro [14]. GASA proteins also participate in plant growth and development [15][16][17][18][19].…”