title: A single amino acid substitution in the MurF UDP-MurNAc-pentapeptide synthetase renders Streptococcus pneumoniae dependent on CO2 and temperature.
abstract: The respiratory tract pathogen Streptococcus pneumoniae encounters different levels of environmental CO2 during transmission, host colonization and disease. About 8% of all pneumococcal isolates are capnophiles that require CO2 -enriched growth conditions. The underlying molecular mechanism for caphnophilic behaviour, as well as its biological function is unknown. Here, we found that capnophilic S. pneumoniae isolates from clonal complex (CC) 156 (i.e. Spain(9V) -3 ancestry) and CC344 (i.e. Norway(NT) -42 ancestry) have a valine at position 179 in the MurF UDP-MurNAc-pentapeptide synthetase. At ≤ 30°C, the growth characteristics of capnophilic and non-capnophilic CC156 strains were equal, but at > 30°C growth and survival of MurF(V) (179) strains was dependent on > 0.1% CO2 -enriched conditions. Expression of MurF(V) (179) in S. pneumoniae R6 and G54 rendered these, otherwise non-capnophilic strains, capnophilic. Time-lapse microscopy revealed that a capnophilic CC156 strain undergoes rapid autolysis upon exposure to CO2 -poor conditions at 37°C, and staining with fluorescently labelled vancomycin showed a defect in de novo cell wall synthesis. In summary, in capnophilic S. pneumoniae strains from CC156 and CC344 cell wall synthesis is placed under control of environmental CO2 levels and temperature. This mechanism might represent a novel strategy of the pneumococcus to rapidly adapt and colonize its host under changing environmental conditions.
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Burghout
authors.forename: Beatríz
authors.initials: B
authors.lastname: Quintero
authors.forename: Linda
authors.initials: L
authors.lastname: Bos
authors.forename: Katrin
authors.initials: K
authors.lastname: Beilharz
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Veening
authors.forename: Marien I
authors.initials: MI
authors.lastname: de Jonge
authors.forename: Mark
authors.initials: M
authors.lastname: van der Linden
authors.forename: Arie
authors.initials: A
authors.lastname: van der Ende
authors.forename: Peter W M
authors.initials: PW
authors.lastname: Hermans
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002245:Carbon Dioxide; D002473:Cell Wall / Q000378:metabolism; D010453:Peptide Synthases / Q000235:genetics* / Q000502:physiology; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D002245:Carbon Dioxide; D010453:Peptide Synthases; C060628:UDP-N-acetylmuramoylalanyl-D-glutamyllysine-D-alanyl-D-alanine ligase