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Enhanced Cationic Charge is a Key Factor in Promoting Staphylocidal Activity of α-Melanocyte Stimulating Hormone via

Jyotsna Singh1, Seema Joshi1, Sana Mumtaz1

  • 1Antimicrobial Research Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110067, India.

Scientific Reports
|August 17, 2016
PubMed

Insights

Increasing the positive charge of the antimicrobial peptide alpha-melanocyte-stimulating hormone (α-MSH) significantly enhanced its ability to kill Staphylococcus aureus, including drug-resistant strains like MRSA.

Area of Science:

  • Microbiology
  • Biochemistry
  • Peptide Science

Background:

  • Antimicrobial resistance is a major global health threat.
  • Staphylococcus aureus (S. aureus) is an opportunistic pathogen with increasing resistance.
  • Alpha-melanocyte-stimulating hormone (α-MSH) shows antimicrobial activity against S. aureus.

Purpose of the Study:

  • To investigate if increasing the cationic charge of α-MSH enhances its antibacterial potential.
  • To design and evaluate novel α-MSH analogues with modified charge.

Main Methods:

  • Designed novel α-MSH analogues by substituting polar residues with lysine and alanine.
  • Assessed peptide conformation and membrane interaction using model vesicles.
  • Determined antibacterial potency against methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA).
  • Evaluated membrane permeabilization, depolarization, and visualized bacterial damage via electron microscopy.

Main Results:

  • Novel analogues maintained α-MSH's conformation and membrane interaction properties.
  • Increased cationic charge significantly boosted antibacterial potency against MSSA and MRSA.
  • The most charged analogue, KKK-MSH, exhibited 18-fold greater binding to bacterial mimics.
  • KKK-MSH demonstrated enhanced membrane permeabilization and depolarization, leading to bacterial membrane disruption.

Conclusions:

  • Increasing the cationic charge of α-MSH improves its staphylocidal activity and membrane-disrupting capability.
  • Enhanced peptides show potent activity against S. aureus without compromising cell selectivity.
  • This study provides a foundation for developing improved α-MSH-based therapeutics against staphylococcal infections.

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