Activity Determinants in Linear Spider Venom Peptide Fragments Against MRSA

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  Activity Determinants in Linear Spider Venom Peptide Fragments Against MRSA Abstract Objective: Using neural networks, we previously identified linear fragments of spider venom peptides active against methicillin-resistant Staphylococcus aureus (MRSA). Among them, peptide IX (IWLSLMKFAGKHL-NH 2 ) with a C -terminal amide displayed high antibacterial potency, whereas its non-amidated analogue, peptide X, was inactive. Peptide IX incorporates into zwitterionic multilamellar liposomes of dioleoylphosphatidylcholine (DOPC) without disrupting them, and also into anionic liposomes of dioleoylphosphatidylglycerol (DOPG) mimicking the MRSA cell membrane, leading to bilayer disruption. This study aims to elucidate the reasons for peptide X inactivation.  Methods: According to ¹H NMR spectroscopy, peptide X in water is governed by the ionization of the His12 residue. ³¹P NMR data show that peptide X interacts with DOPC and DOPG membranes. Monte Carlo simulations revealed conformati...

The protamines of the noble false widow spider Steatoda nobilis provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis

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The protamines of the noble false widow spider Steatoda nobilis provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis

    Abstract

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is very little information about Arthropoda by comparison. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (Order Araneae, Family Theridiidae). To this end, we have developed a protein extraction method that allows the extraction of cysteine-containing protamines suitable for the preparation and analysis of SNBPs from samples where the amount of starting tissue material is limited. We carried out top-down mass spectrometry sequencing and molecular phylogenetic analyses to characterize the protamines of S. nobilis and other spiders. We also used electron microscopy to analyze the chromatin organization of the sperm, and we found it to exhibit liquid-liquid phase spinodal decomposition during the late stages of spermiogenesis. These studies further our knowledge of the distribution of SNBPs within the animal kingdom and provide additional support for a proposed evolutionary origin of many protamines from a histone H1 (H5) replication-independent precursor.


The protamines of the noble false widow spider Steatoda nobilis provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis

Melissa R Leyden, Peter Michalik, Luciana Baruffaldi, Susheen Mahmood, Ladan Kalani, Donald F Hunt, Jose Maria Eirin-Lopez, Maydianne C.B. Andrade, Jeffrey Shabanowitz, Juan Ausió

bioRxiv 2024.06.04.597381; doi: https://doi.org/10.1101/2024.06.04.597381