Premium
c ‐di‐ AMP modulates L isteria monocytogenes central metabolism to regulate growth, antibiotic resistance and osmoregulation
Author(s) -
Whiteley Aaron T.,
Garelis Nicholas E.,
Peterson Bret N.,
Choi Philip H.,
Tong Liang,
Woodward Joshua J.,
Portnoy Daniel A.
Publication year - 2017
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13622
Subject(s) - biology , mutant , biochemistry , microbiology and biotechnology , enzyme , osmotic shock , gene
Summary Cyclic diadenosine monophosphate (c‐di‐AMP) is a conserved nucleotide second messenger critical for bacterial growth and resistance to cell wall‐active antibiotics. In Listeria monocytogenes , the sole diadenylate cyclase, DacA, is essential in rich, but not synthetic media and Δ dacA mutants are highly sensitive to the β‐lactam antibiotic cefuroxime. In this study, loss of function mutations in the oligopeptide importer ( oppABCDF ) and glycine betaine importer ( gbuABC ) allowed Δ dacA mutants to grow in rich medium. Since oligopeptides were sufficient to inhibit growth of the Δ dacA mutant we hypothesized that oligopeptides act as osmolytes, similar to glycine betaine, to disrupt intracellular osmotic pressure. Supplementation with salt stabilized the Δ dacA mutant in rich medium and restored cefuroxime resistance. Additional suppressor mutations in the acetyl‐CoA binding site of pyruvate carboxylase (PycA) rescued cefuroxime resistance and resulted in a 100‐fold increase in virulence of the Δ dacA mutant. PycA is inhibited by c‐di‐AMP and these mutations prompted us to examine the role of TCA cycle enzymes. Inactivation of citrate synthase, but not down‐stream enzymes suppressed Δ dacA phenotypes. These data suggested that c‐di‐AMP modulates central metabolism at the pyruvate node to moderate citrate production and indeed, the Δ dacA mutant accumulated six times the concentration of citrate present in wild‐type bacteria.