A Metabolomic View of Staphylococcus aureus and Its Ser/Thr Kinase and Phosphatase Deletion Mutants: Involvement in Cell Wall Biosynthesis

Abstract

Little is known about intracellular metabolite pools in pathogens such as Staphylococcus aureus. We have studied a particular metabolome by means of the presented LC-MS method. By investigating the central carbon metabolism which includes most of the energy transfer molecules like nucleotides, sugar mono- and biphosphates, and cofactors, a conclusion about phenotypes and stress answers in microorganisms is possible. Quantitative metabolite levels of S. aureus grown in complex lysogeny broth and in minimal medium were compared in the wild-type S. aureus strain 8325 and the isogenic eukaryotic-like protein serine/threonine kinase (DeltapknB) and phosphatase (Deltastp) deletion mutants. Detection of several remarkable differences, e.g., in nucleotide metabolism and especially cell wall precursor metabolites, indicates a previously unreported importance of serine/threonine kinase/phosphatase on peptidoglycan and wall teichoic acid biosynthesis. These findings may lead to new insights into the regulation of staphylococcal cell wall metabolism.

Eukaryote-Like Serine/Threonine Kinases and Phosphatases in Bacteria

“…The importance of PknB and its cognate phosphatase in the synthesis of peptidoglycan and wall teichoic acid was further supported by the impact of the ⌬pknB mutation on S. aureus metabolism (92). Similar division and growth defects, as well as antibiotic susceptibility phenotypes, were described for Streptococcus pyogenes, Streptococcus agalactiae, S. pneumoniae, and Streptococcus mutans (9,37,72,132,144,149,174), as well as Enterococcus faecalis (82).…”

Revisiting the Nucleotide and Aminoglycoside Substrate Specificity of the Bifunctional Aminoglycoside Acetyltransferase(6′)-Ie/Aminoglycoside Phosphotransferase(2″)-Ia Enzyme

“…Four ratios of ATP and GTP were evaluated; one was determined in Staphylococcus aureus (24), two were determined in E. coli (21,22), and a condition using the lowest concentration of GTP (500 M) and highest concentration of ATP (10 mM) reported (23). We followed phosphorylation of tobramycin by AAC(6Ј)-Ie/APH(2Љ)-Ia using [␥-32 P]GTP as the radiolabeled phosphate donor, thus detecting only GTP-dependent phosphorylation, even in the presence of ATP.…”

The Biofilm Inhibitor Carolacton Disturbs Membrane Integrity and Cell Division of Streptococcus mutans through the Serine/Threonine Protein Kinase PknB

“…We therefore infer that carolacton disturbs a process which coordinates cell wall metabolism rather than directly inhibiting a certain enzymatic step in the biogenesis of the cell wall. PknB is suggested to play a central role in cell wall remodeling and is known as an alternative signaling system besides the twocomponent systems (41,45).…”