Prediction and Characterization of Cationic Arginine-Rich Plant Antimicrobial Peptide SM-985 From Teosinte (Zea mays ssp. mexicana)

Abstract

Antimicrobial peptides (AMPs) are effective against different plant pathogens and newly considered as part of plant defense systems. From prokaryotes to eukaryotes, AMPs can exist in all forms of life. SM-985 is a cationic AMP (CAMP) isolated from the cDNA library of Mexican teosinte (Zea mays ssp. mexicana). A computational prediction server running with different algorithms was used to screen the teosinte cDNA library for AMPs, and the SM-985 peptide was predicted as an AMP with high probability prediction values. SM-985 is an arginine-rich peptide and composed of 21 amino acids (MW: 2671.06 Da). The physicochemical properties of SM-985 are very promising as an AMP, including the net charge (+8), hydrophobicity ratio of 23%, Boman index of 5.19 kcal/mol, and isoelectric point of 12.95. The SM-985 peptide has amphipathic α-helix conformations. The antimicrobial activity of SM-985 was confirmed against six bacterial plant pathogens, and the MIC of SM-985 against Gram-positive indicators was 8 µM, while the MIC of SM-985 against Gram-negative indicators was 4 µM. The SM-985 interacting with the bacterial membrane and this interaction were examined by treatment of the bacterial indicators with FITC-SM-985 peptide, which showed a high binding affinity of SM-985 to the bacterial membrane (whether Gram-positive or Gram-negative). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the treated bacteria with SM-985 demonstrated cell membrane damage and cell lysis. In vivo antimicrobial activity was examined, and SM-985 prevented leaf spot disease infection caused by Pst DC3000 on Solanum lycopersicum. Moreover, SM-985 showed sensitivity to calcium chloride salt, which is a common feature of CAMPs.

Prediction and Activity of a Cationic α-Helix Antimicrobial Peptide ZM-804 from Maize

“…Therefore, there is a distinct difference in the effectiveness of ZM-804 peptide on both bacterial groups, whereas Gram-negative bacteria are more sensitive than Gram-positive bacteria. ZM-804 agrees with the SM-985 peptide [ 45 ] in preference for Gram-negative bacteria, although they have no similar composition. Moreover, the MICs and MBCs of the ZM-804 are similar and close to previous studies on other AMPs such as NCR peptides [ 46 , 47 ].…”

“…The activity of peptide NCR035 decreased after being labeled by FITC, and it was measured using PI uptake [ 55 ]. However, the FITC tag did not affect the antimicrobial activity of the SM-985 peptide [ 45 ].…”

“…AMPs have gained a lot of interest in plant protection as a control source with a potentially reduced negative environmental effect and a wide range of activities [ 61 ]. In general, the ZM-804 showed strong antimicrobial activity in planta, which is similar to the SM-985 peptide [ 45 ] and the VG 1 6KRKP peptide, which have significant antimicrobial activity against Xanthomonas oryzae and Xanthomonas campestris -caused disease in rice [ 62 ].…”

Structural stability of antimicrobial peptides rich in tryptophan, proline and arginine: a computational study

“…In recent days, the AMPs are considered as potent alternatives to current chemical antibiotics for treatment of disease-resistant infections. Broad spectrum antimicrobial activity, greater efficacy at lowconcentration, higher specificity toward prokaryotic cells, low propensity for developing resistance and low relative cytotoxicity are the key attributes for considering AMPs in antimicrobial and therapeutic applications (Qutb et al, 2020;Sinha & Shukla, 2019).…”

Isolation of Antimicrobial Genes from Oryza rufipogon Griff by Using a Bacillus subtilis Expression System with Potential Antimicrobial Activities

“…Some recent studies have shown that antimicrobial peptides (AMPs) such as AtR472 derived from Aegilops tauschii Cosson , the cationic antimicrobial gene HCAP-18 expressed in Chinese cabbage, and peptide SM-985 from Teosinte ( Zea mays ssp. mexicana) have significant inhibitory effects on many plant pathogenic bacteria [ 8 , 9 , 10 ]. Besides, antimicrobial peptides have also been used in many fields because of their excellent bacteriostatic effects [ 11 , 12 , 13 , 14 ].…”