Benndorf, R. | bioRxiv Science

bioRxiv2026

3-Hydroxypropanamidines: from antiplasmodial leads to a novel antibacterial scaffold

Arylamino alcohols constitute an established class of antimalarial agents. While this class is best known for its potent antiplasmodial activity, selected members, most notably mefloquine, have also been reported to exhibit antibacterial activity. Structurally related 3-hydroxypropanamidines were developed as highly potent antimalarial agents. Here, we explored the antibacterial activity of three 3-hydroxypropanamidines (4 (BLK278), 5 (BLK280), and 6 (TKK088)) against clinically relevant Gram-positive and Gram-negative bacteria and investigated their cytotoxicity, in vitro pharmacokinetic properties, and proteome-based bacterial response to treatment. We observed good antibacterial activity against Staphylococcus aureus, with 6 (TKK088) displaying the highest activity against multidrug-resistant MRSA and VISA strains. 5 (BLK280) demonstrated the greatest spectrum of activity acting also against clinically relevant Gram-negative strains of Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Klebsiella aerogenes, and Shigella sonnei. In cytotoxicity assays with HUVEC and HAOSMC cells, 4 (BLK278) and the previously reported 7 (TKK129) showed the most favourable overall profiles among the investigated 3-hydroxypropanamidines. The selectivity indices for S. aureus were below 2.5 with clear cell-type-dependent differences for all compounds including mefloquine, suggesting that improving antibacterial selectivity is an important objective for further optimization. In vitro pharmacokinetics showed high plasma protein binding and good human microsomal and plasma stability for all three 3-hydroxypropanamidines. Gel-based proteomic responses revealed a strong impact on the bacterial cell envelope. The observed acute proteomic responses reflect pleiotropic effects and are consistent with earlier reports implicating F0F1-ATPase as a potential molecular target of mefloquine in Streptococcus pneumoniae.

microbiology↗

bioRxiv2022

Human HspB1, HspB3, HspB5 and HspB8: Shaping these Disease Factors during Vertebrate Evolution

Small heat shock proteins (sHSPs) emerged early in evolution and occur in all domains of life and nearly in all species, including humans. Mutations in four sHSPs (HspB1, HspB3, HspB5, HspB8) are associated with neuromuscular disorders. The aim of this study is to investigate the evolutionary forces shaping these sHSPs during vertebrate evolution. We performed comparative evolutionary analyses on a set of orthologous sHSP sequences, based on the ratio of non-synonymous: synonymous substitution rates for each codon. We found that these sHSPs had been historically exposed to different degrees of purifying selection, decreasing in this order: HspB8 > HspB1, HspB5 > HspB3. Within each sHSP, regions with different degrees of purifying selection can be discerned, resulting in characteristic selective pressure profiles. The conserved -crystallin domains were exposed to the most stringent purifying selection compared to the flanking regions, supporting a dimorphic pattern of evolution. Thus, during vertebrate evolution the different sequence partitions were exposed to different and measurable degrees of selective pressures. Among the disease-associated mutations, most are missense mutations primarily in HspB1 and to a minor extent in the other sHSPs. Our data provide an explanation for this disparate incidence. Contrary to the expectation, most missense mutations cause dominant disease phenotypes. Theoretical considerations support a connection between the historic exposure of these sHSP genes to a high degree of purifying selection and the unusual prevalence of genetic dominance of the associated disease phenotypes. Our study puts the genetics of inheritable sHSP-borne diseases into the context of vertebrate evolution.

evolutionary biology↗