Low Cytoplasmic Magnesium Increases the Specificity of the Lon and ClpAP Proteases

Abstract

The bacterium Salmonella enterica serovar Typhimurium narrows down the spectrum of substrates degraded by the proteases Lon and ClpAP in response to low cytoplasmic Mg 2+ , a condition that decreases protein synthesis. This control is exerted by PhoP, a transcriptional regulator activated in low cytoplasmic Mg 2+ that governs proteostasis and is conserved in enteric bacteria. The uncovered mechanism enables bacteria to control the abundance of preexisting proteins.