title: The PAMP c-di-AMP Is Essential for Listeria monocytogenes Growth in Rich but Not Minimal Media due to a Toxic Increase in (p)ppGpp. [corrected].
abstract: Cyclic di-adenosine monophosphate (c-di-AMP) is a widely distributed second messenger that appears to be essential in multiple bacterial species, including the Gram-positive facultative intracellular pathogen Listeria monocytogenes. In this study, the only L. monocytogenes diadenylate cyclase gene, dacA, was deleted using a Cre-lox system activated during infection of cultured macrophages. All ΔdacA strains recovered from infected cells harbored one or more suppressor mutations that allowed growth in the absence of c-di-AMP. Suppressor mutations in the synthase domain of the bi-functional (p)ppGpp synthase/hydrolase led to reduced (p)ppGpp levels. A genetic assay confirmed that dacA was essential in wild-type but not strains lacking all three (p)ppGpp synthases. Further genetic analysis suggested that c-di-AMP was essential because accumulated (p)ppGpp altered GTP concentrations, thereby inactivating the pleiotropic transcriptional regulator CodY. We propose that c-di-AMP is conditionally essential for metabolic changes that occur in growth in rich medium and host cells but not minimal medium.
authors.affiliation: Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Whiteley
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Pollock
authors.affiliation: Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. Electronic address: portnoy@berkeley.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Portnoy
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006158:Guanosine Pentaphosphate / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity; D008815:Mice, Inbred Strains; D013489:Suppression, Genetic
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D015226:Dinucleoside Phosphates; C528998:cyclic diadenosine phosphate; D006158:Guanosine Pentaphosphate; D000262:Adenylyl Cyclases