d‐amino carboxamide‐based recruitment of dinitrophenol antibodies to bacterial surfaces via peptidoglycan remodeling

Abstract

During the past few decades there has been a rapid emergence of multidrug resistant bacteria afflicting human patients. At the same time, reduced output from pharmaceutical industry in this area precipitated a sharp decrease in the approval of new antibiotics. The combination of these factors potentially compromises the ability to effectively combat bacterial infections. While traditional drug discovery efforts continue in the pursuit of small molecule agents that disrupt bacterial growth, non-traditional efforts could serve to complement antimicrobial strategies. We recently demonstrated our ability to remodel the surface of bacterial cells using unnatural D-amino acids displaying the antigenic dinitrophenyl (DNP) handle. These immune stimulant D-amino acids derivatives were metabolically incorporated onto the peptidoglycan of bacteria via a promiscuous surface-anchored transpeptidase. The covalent modification of DNP moieties onto the peptidoglycan led to the anti-DNP antibody opsonization of the bacterial cell surface. Herein, we show that the amidation of the C-terminus to generate DNP-displaying D-amino carboxamide drastically improves antibody recruitment. Antibody opsonization using the D-amino carboxamide agent is observed at lower concentrations than the D-amino acid counterpart. In addition, the recruitment of endogenous antibodies in pooled human serum to the DNP-modified bacterial cell surface is demonstrated for the first time. We envision that the C-terminus amidation of DNP-conjugated D-amino acids could potentially facilitate translation of these results to in vivo animal disease models.

Synthetic Immunotherapeutics against Gram-negative Pathogens

“…During active stages of infection, bacterial cell walls come in direct contact with their human hosts, a feature that can be exploited by the immune system in detecting and eradicating these pathogens (Kieser and Kagan, 2017; Royet, et al, 2011). We have recently demonstrated that synthetic cell wall building blocks can metabolically label the surface of Gram-positive bacteria with antigenic epitopes (Fura, et al, 2016; Fura and Pires, 2015; Fura, et al, 2014; Fura, et al, 2017). In turn, grafting of haptens onto bacterial cell surfaces triggered the recruitment of endogenous antibodies (pools of existing antibodies in humans).…”

Transposon Screen of Surface Accessibility inS. aureus

“…23 The difficulty in finding new efficacious antibiotics against S. aureus highlights the need to explore less conventional therapeutic approaches such as antibiotic adjuvants or immunotherapies. [24][25][26][27][28][29] For example, adjuvants can potentiate antibiotics by improving their accessibility to their cognate molecular targets. Likewise, anti-infective immunotherapeutics (e.g., antibody recruiting agents developed by our lab [24][25][26][27]29 ) work by targeting specific macromolecules on bacterial cell surfaces.…”

Packed Like Sardines– How Surface Crowdedness Impacts Accessibility to Peptidoglycan ofStaphylococcus aureus

“…S. aureus is most commonly observed in skin infections but it can cause more severe internal infections. 11,12 According to the Centers for Disease Control and Prevention (CDC), hard-to-treat methicillin resistant strains of S. aureus (MRSA) infect an estimated 120,000 people and cause ∼20,000 deaths a year in the United States alone. The difficulty in finding new efficacious antibiotics against S. aureus highlights the need to explore less conventional therapeutic approaches such as antibiotic adjuvants or immunotherapies.…”

“…The difficulty in finding new efficacious antibiotics against S. aureus highlights the need to explore less conventional therapeutic approaches such as antibiotic adjuvants or immunotherapies. [10][11][12][13][14][15] For example, adjuvants can potentiate antibiotics by improving their accessibility to their cognate molecular target. Likewise, anti-infective immunotherapeutics (e.g., antibody recruiting agents developed by our lab [10][11][12][13]15 ) work by targeting macromolecules on bacterial cell surfaces.…”

“…[10][11][12][13][14][15] For example, adjuvants can potentiate antibiotics by improving their accessibility to their cognate molecular target. Likewise, anti-infective immunotherapeutics (e.g., antibody recruiting agents developed by our lab [10][11][12][13]15 ) work by targeting macromolecules on bacterial cell surfaces. Despite the pivotal role of surface accessibility in bacterial pathogenesis, to date there has not been a systematic characterization of how molecular size and flexibility control penetration of biomacromolecules across bacterial cell surfaces; information that can directly impact the improvement of current therapies and the development of alternative treatments.…”