N-terminal lysine as a critical determinant of odilorhabdin susceptibility to inactivation by the self-resistance acetyltransferase OatA
Abstract
Odilorhabdins (ODLs) are a novel class of peptide antibiotics that inhibit bacterial translation by binding to the 30S ribosomal subunit. Xenorhabdus nematophila , an ODL-producing bacterium, encodes a highly specialized self-resistance acetyltransferase, OatA, that inactivates ODLs via primary amine modification. In this study, we investigated the structural determinants governing susceptibility of the natural compound NOSO-95C to OatA-mediated inactivation. Using an alanine-scanning library, we identified N -terminal lysine (Lys 1 ) as the key structural determinant of acetyltransferase susceptibility. Expression of oatA in E. coli increased the MIC of NOSO-95C by 64-fold due to rapid OatA-mediated acetylation. In contrast, analog 1 (Lys1→Ala) was no longer discriminated between Oat-A expressing and non-expressing strains, and remained 95.4% unacetylated after 4 h of incubation. Functional assays confirmed that analog 1 retains potent translation inhibition and antibacterial activity despite enzyme exposure. Furthermore, OatA failed to inactivate other amine-containing clinical antibiotics such as aminoglycosides, penicillin, or polymyxins. These results indicate that the side chain of N -terminal lysine is essential for efficient OatA-mediated acetylation of ODLs. Moreover, this single residue can be modified to enable ODLs to evade enzymatic inactivation while preserving their primary mechanism of action. This work provides a clear structure-activity framework for the rational design of next-generation ODLs with enhanced stability against OatA-mediated enzymatic modification.
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BibTeX
@article{racine2026nterminal,
title = {{N-terminal lysine as a critical determinant of odilorhabdin susceptibility to inactivation by the self-resistance acetyltransferase OatA}},
author = {Emilie Racine and Anne Lanois-Nouri and Jessica Houard and Lucile Pantel and Alain Givaudan and Maxime Gualtieri},
journal = {Antimicrobial Agents and Chemotherapy},
year = {2026},
month = oct,
doi = {10.1128/aac.00743-26},
url = {https://hal.science/hal-05848235v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - N-terminal lysine as a critical determinant of odilorhabdin susceptibility to inactivation by the self-resistance acetyltransferase OatA
AU - Emilie Racine
AU - Anne Lanois-Nouri
AU - Jessica Houard
AU - Lucile Pantel
AU - Alain Givaudan
AU - Maxime Gualtieri
PY - 2026
DA - 2026/10/07
JO - Antimicrobial Agents and Chemotherapy
DO - 10.1128/aac.00743-26
UR - https://hal.science/hal-05848235v1
AB - Odilorhabdins (ODLs) are a novel class of peptide antibiotics that inhibit bacterial translation by binding to the 30S ribosomal subunit. Xenorhabdus nematophila , an ODL-producing bacterium, encodes a highly specialized self-resistance acetyltransferase, OatA, that inactivates ODLs via primary amine modification. In this study, we investigated the structural determinants governing susceptibility of the natural compound NOSO-95C to OatA-mediated inactivation. Using an alanine-scanning library, we identified N -terminal lysine (Lys 1 ) as the key structural determinant of acetyltransferase susceptibility. Expression of oatA in E. coli increased the MIC of NOSO-95C by 64-fold due to rapid OatA-mediated acetylation. In contrast, analog 1 (Lys1→Ala) was no longer discriminated between Oat-A expressing and non-expressing strains, and remained 95.4% unacetylated after 4 h of incubation. Functional assays confirmed that analog 1 retains potent translation inhibition and antibacterial activity despite enzyme exposure. Furthermore, OatA failed to inactivate other amine-containing clinical antibiotics such as aminoglycosides, penicillin, or polymyxins. These results indicate that the side chain of N -terminal lysine is essential for efficient OatA-mediated acetylation of ODLs. Moreover, this single residue can be modified to enable ODLs to evade enzymatic inactivation while preserving their primary mechanism of action. This work provides a clear structure-activity framework for the rational design of next-generation ODLs with enhanced stability against OatA-mediated enzymatic modification.
SN - 0066-4804
SN - 1098-6596
ER -