Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: LL-37 preferentially permeabilizes actively dividing cells. E. coli BW25113 cells were grown in M9-glucose minimal medium and mid-logarithmic phase bacteria were then placed on 1% agarose pads with A-C) SYTOX™ Green nucleic acid stain or D-E) propidium iodide. Live images were collected while 3 µl of 50-100 µg/ml LL-37 in water was added to the edge of the agarose pad. Arrows indicate dead cells with evidence of a mid-cell invagination consistent with the formation of a divisome A&B; C&D. Statistical significance was tested by unpaired Student’s t-test comparing the average percentage of dead cells that contained a visible mid-cell invagination consistent with divisome formation and activation from three independent biological replicates. N = 141 to 308 dead cells per replicate measured via SYTOX Green staining and N = 77 to 232 dead cells per replicate for PI mediated killing.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Bacteria, Staining, Activation Assay

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: - LL-37 killing occurs downstream of FtsZ and FtsN recruitment and disassembly and concomitantly with septal closure and AmiB recruitment. A) Imaging of propidium iodide uptake in BW25113 cells expressing FtsZ-GFP exposed to LL-37 B) Characterization of FtsZ-GFP behaviour in LL-37 killed cells C) Imaging of propidium iodide uptake in BW25113 cells expressing FtsN-SPOR-GFP exposed to LL-37 D) Characterization of FtsN-SPOR-GFP behaviour in LL-37 killed cells E) Imaging of propidium iodide uptake in BW25113 cells expressing AmiB-sfGFP exposed to LL-37 F) Characterization of AmiB-sfGFP behaviour in LL-37 killed cells. To assess dying cells (B, D, E), PI+ cells were categorized based on the behaviour of the divisome-localized marker at the time of LL-37 mediated killing. Three biological replicates were assessed in each experiment. N = 29 to 132 dead cells counted for each biological replicate. G) schematic relating the timing of LL-37-mediated killing to the assembly and dissassembly of selected divisome protein marker behaviour.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Imaging, Expressing, Marker

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: Induction of minicells via deletion of minCD leads to aberrant polar localization of the divisome site and induces LL-37-mediated killing from non-septal regions. A) Deletion of minCD or overexpression of FtsZ alters E. coli cell length and the distribution of cell lengths within the population. At least 1700 cells total were measured per strain and cells from three independent experiments were measured. The means of lengths measured in each experiment were compared by a log normal Brown-Forsynthe and Welch’s ANOVA with Dunnett’s T3 post-hoc testing. B) BW2511311 minCD cells show LL-37 mediated killing from polar division sites. The site of LL-37-mediated killing of E. coli K12 vs K1211 minCD bacteria were compared via two-way ANOVA with Šídák’s post-hoc test to determine whether different strains showed different sites of killing C) dying BW25113 or D) filamentous E. coli BW2511311 minC D cell upon exposure to LL-37 in the presence of propidium iodide

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Over Expression, Bacteria

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: - LL-37 induces fission in A) polar E. coli lipid derived supported membrane nanotubes and B) synthetic phosphatidyl choline derived nanotubes. C and D) LL-37 causes transient bulging and thinning of lipid nanotubes concomitant with membrane fission events. E) Polar lipid and POPC-derived nanotubes are disrupted at similar rates F) the presence of polar lipids in nanotube preparations increases the range of nanotube sizes that are disrupted by exposure to LL-37. Fission rates were compared by Student’s t-test while comparisons of nanotube sizes formed to nanotube sizes that underwent fission were compared by Kruskall-Wallis ANOVA with Dunn’s Multiple Comparison post-hoc tests to compare specific groups.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Derivative Assay, Membrane, Comparison

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: - Deletion of queE increases E. coli K12 susceptibility to LL-37 and mCRAMP while overexpression of queE leads to protection from these molecules. A) Deletion of queE results in increased bulk susceptibility to LL-37 and mCRAMP but not to polymyxin B B) Deletion of queE leads to reduced E. coli K12 mean cell length C) live single-cell killing analysis of queE -induced filamentation and killing in E. coli K12 shows that cells that are made filamentous via queE expression from pRL03 are significantly protected from LL-37 mediated killing. Statistical differences in bulk susceptibility to LL-37, mCRAMP or polymyxin B were assessed by paired t-test of the percent survival following exposure to each compound as assessed by plate counting. Differences in cell lengths were assessed by one-way ANOVA comparing the average cell lengths from three independent experiments (N=50 cells counted for each group). Differences in single cell survival were assessed by comparing the percentage of propidium iodide negative cells from each group following exposure to 100 μg/ml LL-37 by one-way ANOVA with Holm-Šídák’s multiple comparison post-hoc testing.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Over Expression, Expressing, Comparison

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: - Killing behaviour of LL-37 in heterogenous populations of E. coli K12. A) Induction of filamention from pBAD- queE is heterogenous and PI-staining is preferentially observed in the shorter, dividing subpopulation of bacteria B) Cell length analysis of PI-stained LL-37-killed bacteria in K12 + pBAD- queE C) Z-ring lifetime analysis in cells expressing QueE shows increased stability of Z-rings D) filamentous cells may be killed by LL-37 whe Z-ring disassembly proceeds (white arrows). Differences in cell length and FtsZ lifetime were assessed by Student’s t-test.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Staining, Bacteria, Expressing

Journal: bioRxiv

Article Title: Division-arrest induced filamentation protects uropathogenic Escherichia coli from killing by the cathelicidin antimicrobial peptide LL-37

doi: 10.64898/2026.01.29.702582

Figure Lengend Snippet: - Filamentation induced by overexpression of QueE, SulA or DamX leads to enhanced LL-37 resistance in uropathogenic E. coli . A) QueE mediates low Mg 2+ induced increased cell length in UTI89 B) Overexpression of the cell division inhibitor SulA increases mean UPEC cell length C) Overexpression of DamX increases mean UPEC cell length. Statistical differences in cell length were assessed by Kruskal-Wallis ANOVA with Dunn’s post-hoc test. The median cell length is indicated on the axis for each strain and condition D - F) filamentation induced by QueE, SulA or DamX increases resistance to LL-37 mediated killing, as assessed by measuring propidium iodide uptake. Statistical significance was assessed by Kruskal-Wallis ANOVA with Dunn’s post-hoc test.

Article Snippet: Stock solution of 1 mM LL-37 (Catalog. no HY-P1222, MedChemExpress) was prepared in deionized water and stored at −80°C.

Techniques: Over Expression

Journal: PLOS One

Article Title: DnaK supports intracellular persistence of Staphylococcus xylosus and confers mechanical resilience to a human breast cancer cell line

doi: 10.1371/journal.pone.0341069

Figure Lengend Snippet: (A) Growth of wild-type, ∆dnaK, and ∆dnaK-C strains under hypoxic conditions (1% O₂). OD₆₀₀ measurements and CFU enumeration were performed at indicated time points. (B) Survival of strains following treatment with LL-37 (10 µg/mL, 2 h). Viable CFUs were determined by plating. Data represent means ± SEM from three independent experiments. Differences among groups were analyzed by one-way ANOVA. p < 0.05; ns, not significant.

Article Snippet: To test hypoxia tolerance, bacteria were cultured in an anaerobic chamber (1% O2, 5% CO2, balanced N2; Whitley H35 Hypoxystation) for 12 h. LL-37 peptide (InvivoGen) was used at 10 μg/mL for 1 h in PBS with 1% BSA.

Techniques: