<i>Listeria monocytogenes</i> requires cellular respiration for NAD⁺ regeneration and pathogenesis.

Abstract

Cellular respiration is essential for multiple bacterial pathogens and a validated antibiotic target. In addition to driving oxidative phosphorylation, bacterial respiration has a variety of ancillary functions that obscure its contribution to pathogenesis. We find here that the intracellular pathogen <i>Listeria monocytogenes</i> encodes two respiratory pathways which are partially functionally redundant and indispensable for pathogenesis. Loss of respiration decreased NAD⁺ regeneration, but this could be specifically reversed by heterologous expression of a water-forming NADH oxidase (NOX). NOX expression fully rescued intracellular growth defects and increased <i>L. monocytogenes</i> loads >1000-fold in a mouse infection model. Consistent with NAD⁺ regeneration maintaining <i>L. monocytogenes</i> viability and enabling immune evasion, a respiration-deficient strain exhibited elevated bacteriolysis within the host cytosol and NOX expression rescued this phenotype. These studies show that NAD⁺ regeneration represents a major role of <i>L. monocytogenes</i> respiration and highlight the nuanced relationship between bacterial metabolism, physiology, and pathogenesis.