Biology subjects

Albin, J. S.

Publications and source records attributed to Albin, J. S..

4 recordsLinked to original sources

bioRxiv2026

Modulation of the human cathelicidin dimerization interface separates antimicrobial activity from mammalian membrane disruption

The human CAMP gene product LL-37 is a prototypical cationic host defense peptide with potent activity against gram-negative bacteria. The development of LL-37 and other membrane-active host defense peptides as antibiotics, however, is limited in part by their activity against mammalian membranes. To better understand the structural features underlying LL-37 functions, we reconceived of LL-37 as a small protein and systematically ablated the sidechain content of entire surfaces while preserving helical character. This approach revealed that selected modifications within surface m4 retain wild-type levels of activity against gram-negative bacteria while disrupting activity against mammalian membranes by >100-fold. Separation of antimicrobial and mammalian membrane activities mapped primarily to residues I24 and L28, and was attributable to a combination of disrupted oligomerization and decreased hydrophobic content within the dimerization interface. Modulation of the LL-37 dimerization interface thus constitutes a rational pathway by which to engineer derivatives with improved therapeutic potential.

biochemistry↗

bioRxiv2025

Separability of antibacterial and membranolytic activity in the human host defense peptide LL-37

The human CAMP gene product LL-37 is thought to exert direct antimicrobial activity against gram-negative bacteria via membrane disruption. In the course of structure-activity relationship studies of LL-37 aimed at developing peptidomimetic antibiotics, however, we incidentally noted mutations in LL-37 that globally inhibit membrane disruption in both mammalian and gram-negative bacterial cells. Despite their diminished capacity for membranolysis, these variants retained full antibacterial activity against gram-negative bacteria. While testing LL-37 and derivatives thereof against clinical isolates of Pseudomonas aeruginosa from patients with cystic fibrosis, we further noted unusually high rates of elevated minimum inhibitory concentrations for LL-37. Further evaluation of these clinical isolates revealed that they are fully permeabilized by LL-37 without being killed. Thus, we have identified variants of LL-37 that kill gram-negative bacteria without permeabilizing, and gram-negative bacteria that are permeabilized by LL-37 without being killed. This may suggest the existence of one or more mechanisms other than membrane disruption by which LL-37 can kill gram-negative bacteria, which may open up new avenues for antibiotic development based on the naturally evolved, non-membrane targets of human host defense peptides.

microbiology↗

bioRxiv2025

Mimicry of the LL-37 N-terminus enhances the activity of short human cathelicidin derivatives

Issues such as potency and stability limit our ability to realize the potential of host defense peptides (HDPs) to serve as new antibiotics. Informed by our prior structure-activity work, we demonstrate that transposition of an N-terminal biphenyl motif from full-length LL-37 onto the previously-described central activity region (residues 18-29) improves activity against gram-negative bacteria by >16-fold. We further improve upon this lead derivative, termed FF-14, using stabilizing modifications such as D-amino acids and C-terminal amidation as well as selected N-lipidation moieties, and demonstrate the transferability of biphenyl motif activity to longer cathelicidin scaffolds. Mechanistic interrogation reveals that the biphenyl pharmacophore increases both inner and outer membrane permeabilization while promoting helical structure in the 14-mer without directly impacting peptide stability. Inclusion of the LL-37 biphenyl motif is thus a portable strategy for augmenting short cathelicidin activity and better approximating the activity profile of LL-37 itself in short sequences.

microbiology↗

bioRxiv2025

Peptaibiotic-inspired antimicrobials based on human cathelicidin

The prevailing model of cathelicidin function holds that peptide helicity leads to membrane permeabilization, which in turn leads to killing of gram-negative bacteria. Using a paired Ala-Aib mutagenesis approach to isolate sidechain and structure-dependent functions, we demonstrate here that the effect of helicity on gram-negative killing in a model cathelicidin-derived scaffold is species-dependent. We then leverage this insight to derive lead compounds with up to 32-fold improvements in selectivity for bacterial over mammalian cells. Further interrogation of the mechanistic basis for selectivity demonstrates that, while helicity may predict permeabilization, permeabilization does not predict killing of gram-negative bacteria. Thus, neither helicity nor permeabilization is a universal requirement for cathelicidin-mediated killing.

microbiology↗