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

Abstract

Antimicrobial peptides (AMPs) are small molecules consisting of less than fifty residues of amino acids. Plant AMPs establish the first barrier of defense in the innate immune system in response to invading pathogens. The purpose of this study was to isolate new AMPs from the Zea mays L. inbred line B73 and investigate their antimicrobial activities and mechanisms against certain essential plant pathogenic bacteria. In silico, the Collection of Anti-Microbial Peptides (CAMPR3), a computational AMP prediction server, was used to screen a cDNA library for AMPs. A ZM-804 peptide, isolated from the Z. mays L. inbred line B73 cDNA library, was predicted as a new cationic AMP with high prediction values. ZM-804 was tested against eleven pathogens of Gram-negative and Gram-positive bacteria and exhibited high antimicrobial activities as determined by the minimal inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs). A confocal laser scanning microscope observation showed that the ZM-804 AMP targets bacterial cell membranes. SEM and TEM images revealed the disruption and damage of the cell membrane morphology of Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato (Pst) DC3000 caused by ZM-804. In planta, ZM-804 demonstrated antimicrobial activity and prevented the infection of tomato plants by Pst DC3000. Moreover, four virulent phytopathogenic bacteria were prevented from inducing hypersensitive response (HR) in tobacco leaves in response to low ZM-804 concentrations. ZM-804 exhibits low hemolytic activity against mouse red blood cells (RBCs) and is relatively safe for mammalian cells. In conclusion, the ZM-804 peptide has a strong antibacterial activity and provides an alternative tool for plant disease control. Additionally, the ZM-804 peptide is considered a promising candidate for human and animal drug development.

Evaluation of Three Antimicrobial Peptides Mixtures to Control the Phytopathogen Responsible for Fire Blight Disease

“…Additionally, HR bioassays allowed to infer on the low or undetectable toxicity of the AMPs tested, since no or low necrosis could be observed after 1 h of exposure to the peptide mixtures. Similar assays have been previously performed to assess the toxicity and/or bactericidal efficacy of AMPs against phytopathogenic bacteria [16,40,46,58]. Synergetic effects in combinations of AMPs with coadjuvants, resulting in low necrosis, had previously been advanced [40], which supports our findings.…”

“…The effects of AMPs on E. amylovora and their use as a control measure for this bacterium have been reported in several studies over the last 15 years [16,[27][28][29][30][31]. Recently, we have demonstrated the bioactivity of two AMPs against E. amylovora [17], namely, RW-BP100 and CA-M, which had already been reported to display activity against pathogenic bacteria but never tested against the causative agent of the fire blight disease [32][33][34].…”

“…Current control measures are mainly based on preventive action against fire blight (cultural control, such as, pruning of early-stage infected trees for example), and/or copperbased phytosanitary compounds and antibiotic applications (chemical control), which is prohibited in the European Union with a few exceptions, due to the dramatic rise of antibiotic resistance [7][8][9][10][11]. Alternative sustainable control methods of E. amylovora have been explored extensively in the last few years, such as, the use of antagonistic bacteria [12], bacteriophages [13], essential oils [14], and antimicrobial peptides (AMPs) [15][16][17].…”

Host-Defense Peptides as New Generation Phytosanitaries: Low Toxicity and Low Induction of Antimicrobial Resistance

“…A cationic alpha-helix antimicrobial peptide (ZM-804) from maize (Zea mays, line B73) was discovered by in silico screening a cDNA library, and then synthesized and tested against eleven pathogens of Gram-negative and Gram-positive species, displaying a high antimicrobial activity [58]. Thus, it was observed by SEM and TEM microcopy that the peptide disrupted the cell membrane of Clavibacter michiganensis subsp.…”

Antimicrobial Peptides from Plants: A cDNA-Library Based Isolation, Purification, Characterization Approach and Elucidating Their Modes of Action

“…As a product, it is insoluble, tightly packed, forms denatured inclusion bodies, is biologically inactive, and needs further folding change, solubilization, and downstream purification [34,35]. On the other hand, the B. subtilis system releases peptides into its extracellular space and has broad-spectrum antimicrobial gene expression capability [36][37][38][39][40]. The products of this expression system are biologically active and require simple downstream processing [41,42].…”