Biology subjects

Gorr, S.-U.

Publications and source records attributed to Gorr, S.-U..

5 recordsLinked to original sources

bioRxiv2025

Targeted Modification of the Antimicrobial Peptide DGL13K Reveals a Naturally Optimized Sequence for Topical Applications.

Antimicrobial peptides are potential alternatives to conventional antibiotics, primarily due broad spectrum activity and low propensity for inducing bacterial resistance. However, their clinical translation faces challenges, including peptide stability and potential mammalian cell toxicity. This study centers on DGL13K, an all D-amino acid peptide, which overcomes proteolytic susceptibility and demonstrates notable stability and broad-spectrum bactericidal activity without inducing de novo bacterial resistance. This work aimed to enhance the therapeutic properties of DGL13K by using targeted modifications to increase antimicrobial potency and decrease toxicity, as determined by hemolysis. DGL13K derivatives were synthesized and tested, involving amino acid substitutions, stereochemical alterations, and N-terminal functionalization with polyethylene glycol (PEG) or myristoylate. While some modifications altered bacterial specificity and reduced hemolytic activity, none of the tested alterations resulted in a substantial overall improvement compared to the parent DGL13K sequence. Furthermore, the antibacterial efficacy of DGL13K and its variants was significantly inhibited in the presence of 50% serum, suggesting limitations for systemic applications. The findings suggest that the DGL13K sequence, derived from an evolutionarily selected protein, is already highly optimized. Given its stability, broad-spectrum efficacy, in vivo activity, low resistance profile, and high safety margin, DGL13K is a promising therapeutic candidate for topical/localized infections.

biochemistry↗

bioRxiv2024

Resisting the resistance: The antimicrobial peptide DGL13K selects for small colony variants of Staphylococcus aureus that show increased resistance to its stereoisomer LGL13K, but not to DGL13K.

About 30% of the population are nasal carriers of Staphylococcus aureus, a leading cause of bacteremia, endocarditis, osteomyelitis, skin and soft tissue infections. Antibiotic-resistant bacteria, in particular, are an increasing problem in both hospital and community settings. In this study, we sought to determine the cellular consequences of long-term exposure of S. aureus to the antimicrobial peptide stereo-isomers, DGL13K and LGL13K. Both peptides selected for mutations in the chorismate/menaquinone biosynthetic pathway, which resulted in increased resistance to LGL13K but not DGL13K. DGL13K-selected isolates showed a mutation in aroF, while menA and menH were mutated in LGL13K-selected isolates. The latter also contained a mutation of frsA. The peptide-selected isolates exhibited golden coloration, suggesting increased production of the carotenoid staphyloxanthin, which could enhance resistance to cationic AMPs. The peptide-selected isolates grew as small colony variants, which have also been associated with resistance to AMPs. Addition of menaquinone to the growth medium reduced the generation time of DGL13K-selected mutants, but not LGL13K-selected mutants. Instead, the latter showed greatly reduced ATP-levels, suggesting defective electron transport, which is also associated with menadione auxotrophism. The mechanisms behind the differential effect of DGL13K and LGL13K on S. aureus resistance remain to be elucidated. The finding that DGL13K induced resistance to the stereo-isomer LGL13K but not to DGL13K itself, suggests that peptide primary structure is responsible for inducing bacterial defense mechanisms but the peptide secondary structure determines if the defense mechanisms are effective against each peptide.

microbiology↗

bioRxiv2023

The oral pathogen Porphyromonas gingivalis resists the antimicrobial peptide LGL13K and evades the D-enantiomer by synonymous mutations in hagA

Porphyromonas gingivalis is a keystone pathogen for periodontal disease. The bacteria are black-pigmented and require heme for growth. P. gingivalis exhibit resistance to many antimicrobial peptides, including the L-enantiomer of the antimicrobial peptide GL13K, which contributes to their success in the oral cavity. P. gingivalis W50 was resistant to LGL13K but susceptible to the stereo-isomer DGL13K. Upon prolonged exposure to DGL13K, a novel non-pigmented mutant was isolated that showed a low minimum inhibitory concentration and two-fold extended minimum duration for killing by DGL13K, consistent with tolerance to this peptide. The DGL13K tolerant bacteria exhibited synonymous mutations in the hagA gene. The mutations did not prevent mRNA expression but were predicted to alter mRNA structure. The non-pigmented bacteria were deficient in hemagglutination and hemoglobin binding, suggesting that the HagA protein was not expressed. This was supported by whole cell ELISA and gingipain activity assays, which suggested the absence of HagA but not two closely related gingipains. In vivo virulence was similar for wild-type and non-pigmented bacteria in the Galleria mellonella model. Loss of the hemagglutinin HagA may allow bacteria to escape from a biofilm that is under attack by antimicrobial peptides.

microbiology↗

bioRxiv2020

The antimicrobial peptide DGL13K is active against resistant gram-negative bacteria and subinhibitory concentrations stimulate bacterial growth without causing resistance

Antimicrobial peptides may be alternatives to traditional antibiotics with reduced bacterial resistance. The antimicrobial peptide GL13K was derived from the salivary protein BPIFA2. This study determined the relative activity of the L-and D-enantiomers of GL13K to wild-type and drug-resistant strains of three gram-negative species and against Pseudomonas aeruginosa biofilms. DGL13K displayed in vitro activity against ESBL and KPC-producing Klebsiella pneumoniae (MICs 16-32 g/ml), MDR and XDR P. aeruginosa, and XDR Acinetobacter baumannii carrying metallo-beta-lactamases (MICs 8-32 g/ml). P. aeruginosa showed low inherent resistance to DGL13K and the increased metabolic activity and growth caused by sub-MIC concentrations of GL13K peptides did not result in acquired bacterial resistance. Daily dosing for approximately two weeks did not increase the MIC of DGL13K or cause cross-resistance between LGL13K and DGL13K. These data suggest that DGL13K is a promising candidate antimicrobial peptide for further development.

microbiology↗

bioRxiv2020

The parotid secretory protein BPIFA2 is a salivary surfactant that affects LPS action

Saliva plays important roles in the mastication, swallowing and digestion of food, speech and lubrication of oral mucosa, antimicrobial and anti-inflammatory activity and control of body temperature in grooming animals. The salivary protein BPIFA2 (BPI fold containing family A member 2; former names: Parotid Secretory Protein, PSP, SPLUNC2, C20orf70) is related to lipid-binding and LPS-binding proteins expressed in mucosa. Indeed, BPIFA2 binds LPS but the physiological role of BPIFA2 remains to be determined. To address this question, Bpifa2 knockout (Bpifa2tm1(KOMP)Vlcg) (KO) mice were phenotyped with a special emphasis on saliva and salivary glands. Saliva collected from KO mice was less able to spread on a hydrophobic surface than wild-type saliva and the surface tension of KO saliva was close to that of water. These data suggest that BPIFA2 is a salivary surfactant that is mainly responsible for the low surface tension of mouse saliva. The reduced surfactant activity of KO saliva did not affect consumption of dry food or grooming, but saliva from KO mice contained less LPS than wild-type saliva. Indeed, mice lacking BPIFA2 responded to ingested LPS with an increased stool frequency, suggesting that BPIFA2 plays a role in the solubilization and activity of ingested LPS. Consistent with these findings, BPIFA2-depleted mice also showed increased insulin secretion and metabolomic changes that were consistent with a mild endotoxemia. These results support the distal physiological function of a salivary protein and reinforce the connection between oral biology and systemic disease.

physiology↗