Biogenic Amine-Containing 1,4-Naphthoquinones Mediate Extracellular Electron Transfer in <i>Lactiplantibacillus plantarum</i>

Abstract

Lactiplantibacillus plantarum, a lactic acid gut bacterium, uses exogenous quinones to facilitate extracellular electron transfer (EET) via type II NADH dehydrogenase (Ndh2). To probe Ndh2 specificity, we designed and evaluated a library of biogenic amine-substituted 1,4-naphthoquinones in an Ndh2-dependent EET assay. Analysis of mediator Ndh2 binding interactions revealed that activity correlates with key binding interactions. Specifically, mediators containing aromatic substitutions elicit favorable Ndh2 interactions, promoting EET.