Elucidating the mechanism of microbial thermogenesis

Abstract

Organisms necessarily release heat energy in their pursuit of survival. This process is known as cellular thermogenesis and is implicated in many processes from cancer metabolism to spontaneous farm fires1,2. However, the molecular basis for this fundamental phenomenon is yet to be elucidated. Here, we show that the major players involved in cellular thermogenesis are the protein kinases ArcB, GlnL, and YccC in Escherichia coli. We also reveal the substrate-level control of ATP-driven autophosphorylation that governs cellular thermogenesis. Through live-cell microcalorimetric experimentation, we find that only three of the 231 regulatory proteins, when knocked out in a model Escherichia coli strain, dysregulate cellular thermogenesis. This dysregulation can be seen in an average 25% or greater increase in heat output by these cells. We also discover that both heat output and intracellular ATP levels are maximal during the late log phase of growth. Our results demonstrate a correlation between ATP concentrations in the cell and a cells ability to generate excess heat. We expect this work to be the foundation for engineering a new generation of thermogenically-tuned organisms for a variety of applications.