Histone H1 kills MRSA

Area of Science:

• Microbiology
• Immunology
• Biochemistry

Background:

• Histones possess antimicrobial properties, known since the 1940s, but their precise mechanisms remain largely unelucidated.
• Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant public health challenge due to its resistance to antibiotics.

Purpose of the Study:

• To elucidate the mechanism by which histone H1 exerts antimicrobial activity against MRSA.
• To investigate the potential role of histone H1 in combating MRSA infections in vivo.

Main Methods:

• Utilized selective evolution and genome-wide transposon library screening to identify mechanisms of MRSA susceptibility to histone H1.
• Conducted physiological and pharmacological experiments to understand histone H1-MRSA interactions.
• Analyzed histone H1 localization in bacterial cells and patient abscess samples.

Main Results:

• Histone H1 demonstrates potent antimicrobial activity against MRSA, even under challenging conditions like the presence of divalent cations and serum.
• Histone H1 binds to wall teichoic acids, permeabilizes the bacterial membrane, and enters the cell.
• Intracellular accumulation of histone H1 in association with bacterial DNA was observed.
• Anti-histone H1 antibodies inhibited neutrophil extracellular trap-mediated killing of MRSA.
• Histone H1 colocalized with bacterial DNA in MRSA-infected patient abscesses.

Conclusions:

• Histone H1 employs a multi-step mechanism involving cell wall binding, membrane permeabilization, and intracellular DNA association to kill MRSA.
• Histone H1 plays a role in the innate immune response against MRSA, particularly within neutrophil extracellular traps.
• These findings suggest histone H1 as a potential therapeutic agent against antibiotic-resistant bacterial infections.