title: Kinase activity of overexpressed HipA is required for growth arrest and multidrug tolerance in Escherichia coli.
abstract: Overexpression of the HipA protein of the HipBA toxin/antitoxin module leads to multidrug tolerance in Escherichia coli. HipA is a "toxin" that causes reversible dormancy, whereas HipB is an antitoxin that binds HipA and acts as a transcriptional repressor of the hipBA operon. Comparative sequence analysis shows that HipA is a member of the phosphatidylinositol 3/4-kinase superfamily. The kinase activity of HipA was examined. HipA was autophosphorylated in the presence of ATP in vitro, and the purified protein appeared to carry a single phosphate group on serine 150. Thus, HipA is a serine kinase that is at least partially phosphorylated in vivo. Overexpression of HipA caused inhibition of cell growth and increase in persister formation. Replacing conserved aspartate 309 in the conserved kinase active site or aspartate 332 in the Mg2+-binding site with glutamine produced mutant proteins that lost the ability to stop cellular growth upon overexpression. Replacing serine 150 with alanine yielded a similarly inactive protein. The mutant proteins were then examined for their ability to increase antibiotic tolerance. Cells overexpressing wild-type HipA were highly tolerant to cefotaxime, a cell wall synthesis inhibitor, to ofloxacin, a fluoroquinolone inhibitor of DNA gyrase, and to topoisomerase IV and were almost completely resistant to killing by mitomycin C, which forms DNA adducts. The mutant proteins did not protect cells from cefotaxime or ofloxacin and had an impaired ability to protect from mitomycin C. Taken together, these results suggest that the protein kinase activity of HipA is essential for persister formation.
authors.affiliation: Department of Biology, Northeastern University, 405 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Frederick F
authors.initials: FF
authors.lastname: Correia
authors.forename: Anthony
authors.initials: A
authors.lastname: D'Onofrio
authors.forename: Tomas
authors.initials: T
authors.lastname: Rejtar
authors.forename: Lingyun
authors.initials: L
authors.lastname: Li
authors.forename: Barry L
authors.initials: BL
authors.lastname: Karger
authors.forename: Kira
authors.initials: K
authors.lastname: Makarova
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Kim
authors.initials: K
authors.lastname: Lewis
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003470:Culture Media; D004361:Drug Tolerance / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D029968:Escherichia coli Proteins; C070741:hipA protein, E coli; D017346:Protein Serine-Threonine Kinases