Purification and characterization of a novel delta-lysin variant that inhibits Staphylococcus aureus and has limited hemolytic activity

• Published in: Peptides (New York, N.Y. : 1980) Vol. 31; no. 9; pp. 1661 - 1668
• Main Authors: Al-Mahrous, Mohammed, Sandiford, Stephanie K., Tagg, John R., Upton, Mathew
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.2010; Elsevier
• Subjects: Amino Acid Sequence; Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antibacterial peptides; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Bacterial Proteins - pharmacology; Biological and medical sciences; Cercopithecus aethiops; Coagulase-negative staphylococci; Delta-lysin (DL); Fundamental and applied biological sciences. Psychology; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; Hemolysin Proteins - chemistry; Hemolysin Proteins - genetics; Hemolysin Proteins - isolation & purification; Hemolysin Proteins - pharmacology; Hemolysis; Hemolytic Agents - chemistry; Hemolytic Agents - isolation & purification; Hemolytic Agents - pharmacology; Hot Temperature; Humans; Molecular Sequence Data; Molecular Weight; MRSA; Osmolar Concentration; Peptides - chemistry; Peptides - genetics; Peptides - isolation & purification; Peptides - pharmacology; Protein Processing, Post-Translational; Protein Stability; Sequence Alignment; Staphylococcus aureus - drug effects; Staphylococcus aureus - genetics; Staphylococcus epidermidis - genetics; Staphylococcus epidermidis - metabolism; Vero Cells; Vertebrates: endocrinology; Delta-lysin (DL); Antibacterial peptides; MRSA; Coagulase-negative staphylococci; Characterization; Variant; Purification; Peptides; Antibacterial agent
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2010.06.006

Delta-lysins (DL) that are produced by various species of staphylococci are not widely known for their antimicrobial activity. We have purified and characterized a novel DL variant, E229DL and examined its spectrum of inhibitory activity. The biological activity of E229DL, produced by Staphylococcus epidermidis strain E229, shows relatively broad-spectrum activity against Gram-positive pathogens, including representatives of MRSA and epidemic MRSA type 15. E229DL was purified to homogeneity from 95% acidified-methanol extracts of cell cultures by using a series of reversed-phase chromatographic separations. The fully processed form of E229DL is a 25-amino-acid peptide with a predicted mass of 2841.4 Da, but the purified biologically active molecule appears to be N-formylated (mass 2867.33 Da). The DL gene (hld) resembles that of other types of DL, but differs in five codons with hld in Staphylococcus aureus (26 residues) and one codon with the closest homolog, the hld-II in S. warneri (25 residues). The characterization of E229DL showed that its activity is stable in agar exposed to high temperatures (80 °C/45 min). In addition, biological testing of the native and synthetic peptides against a range of human and animal erythrocytes and Vero cells indicated that E229DL is an antibacterial agent with no detectable cytopathic effects at concentrations equivalent to the minimum inhibitory concentration for EMRSA15-A208. Initial investigation of the mode of action of E229DL indicated that it is rapidly lytic for target cells. This is the first description of a native form of DL having only limited cytotoxic activity for eukaryotic cells at concentrations that are inhibitory to staphylococci.