Pneumococcal Genetic Transformation During Colonization and Biofilm Formation

Håkansson, Anders; Marks, Laura R.; Håkansson, Anders P.

doi:10.1016/b978-0-12-410530-0.00007-7

Cited by 2 publications

(2 citation statements)

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“…Streptococcus pneumoniae (pneumococcus) is a common commensal bacterium that colonizes the human nasopharynx as biofilms (Donkor, ; Chao et al ., ; Hakansson et al ., ; Short and Diavatopoulos, ). S. pneumoniae can become an opportunistic pathogen in individuals recovering from influenza or with compromised immune systems, causing a number of serious respiratory and invasive diseases, such as pneumonia, otitis media, bacteremia and meningitis (Henriques‐Normark and Tuomanen, ; Vernatter and Pirofski, ; Ferreira and Gordon, ; Gratz et al ., ; Oliver and Swords, ).…”

Section: Introductionmentioning

confidence: 99%

Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39

Tsui

Zheng

Magallon

et al. 2016

Molecular Microbiology

269

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SUMMARY In ellipsoid-shaped ovococcus bacteria, such as the pathogen Streptococcus pneumoniae (pneumococcus), side-wall (peripheral) peptidoglycan (PG) synthesis emanates from midcells and is catalyzed by the essential class B penicillin-binding protein PBP2b transpeptidase (TP). We report that mutations that inactivate the pneumococcal YceG-domain protein, Spd_1346 (renamed MltG), remove the requirement for PBP2b. ΔmltG mutants in unencapsulated strains accumulate inactivation mutations of class A PBP1a, which possesses TP and transglycosylase (TG) activities. The “synthetic viable” genetic relationship between Δpbp1a and ΔmltG mutations extends to essential ΔmreCD and ΔrodZ mutations that misregulate peripheral PG synthesis. Remarkably, the single MltG(Y488D) change suppresses the requirement for PBP2b, MreCD, RodZ, and RodA. Structural modeling and comparisons, catalytic-site changes, and an interspecies chimera indicate that pneumococcal MltG is the functional homologue of the recently reported MltG endo-lytic transglycosylase of Escherichia coli. Depletion of pneumococcal MltG or mltG(Y488D) increases sphericity of cells, and MltG localizes with peripheral PG synthesis proteins during division. Finally, growth of Δpbp1a ΔmltG or mltG(Y488D) mutants depends on induction of expression of the WalRK TCS regulon of PG hydrolases. These results fit a model in which MltG releases anchored PG glycan strands synthesized by PBP1a for crosslinking by a PBP2b:RodA complex in peripheral PG synthesis.

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Section: Introductionmentioning

confidence: 99%

Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39

Tsui

Zheng

Magallon

et al. 2016

Molecular Microbiology

269

View full text Add to dashboard Cite

show abstract

“…S. pneumoniae is a common commensal bacterium that primarily colonizes the human nasopharynx (Donkor, 2013 ; Chao et al, 2014 ; Hakansson et al, 2015 ; Short and Diavatopoulos, 2015 ), but can become an opportunistic pathogen, causing several serious respiratory and invasive diseases (Henriques-Normark and Tuomanen, 2013 ; Vernatter and Pirofski, 2013 ; Ferreira and Gordon, 2015 ; Gratz et al, 2015 ; Oliver and Swords, 2015 ). Therefore, the Pst1 and Pst2 transporters must mediate P i acquisition from several niches with vastly different P i concentrations in human hosts (Orihuela et al, 2001 ; Wilson, 2005 , 2008 ).…”

Section: Introductionmentioning

confidence: 99%

Physiological Roles of the Dual Phosphate Transporter Systems in Low and High Phosphate Conditions and in Capsule Maintenance of Streptococcus pneumoniae D39

Zheng

Sinha

Wayne

et al. 2016

Front. Cell. Infect. Microbiol.

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Unlike most bacteria, Streptococcus pneumoniae (pneumococcus) has two evolutionarily distinct ABC transporters (Pst1 and Pst2) for inorganic phosphate (Pi) uptake. The genes encoding a two-component regulator (PnpRS) are located immediately upstream of the pst1 operon. Both the pst1 and pst2 operons encode putative PhoU-family regulators (PhoU1 and PhoU2) at their ends. This study addresses why S. pneumoniae contains dual Pi uptake systems and the regulation and contribution of the Pst1 and Pst2 systems in conditions of high (mM) Pi amount and low (μM) Pi amount. We show that in unencapsulated mutants, both pst1 and pst2 can be deleted, and Pi is taken up by a third Na+/Pi co-transporter, designated as NptA. In contrast, either pst1 or pst2 is unexpectedly required for the growth of capsule producing strains. We used a combination of mutational analysis, transcript level determinations by qRT-PCR and RNA-Seq, assays for cellular PnpR~P amounts by SDS-PAGE, and pulse-Pi uptake experiments to study the regulation of Pi uptake. In high Pi medium, PhoU2 serves as the master negative regulator of Pst2 transporter function and PnpR~P levels (post-transcriptionally). ΔphoU2 mutants have high PnpR~P levels and induction of the pst1 operon, poor growth, and sensitivity to antibiotics, possibly due to high Pi accumulation. In low Pi medium, Pst2 is still active, but PnpR~P amount and pst1 operon levels increase. Together, these results support a model in which pneumococcus maintains high Pi transport in high and low Pi conditions that is required for optimal capsule biosynthesis.

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Pneumococcal Genetic Transformation During Colonization and Biofilm Formation

Cited by 2 publications

References 73 publications

Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39

Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39

Physiological Roles of the Dual Phosphate Transporter Systems in Low and High Phosphate Conditions and in Capsule Maintenance of Streptococcus pneumoniae D39

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