Gene expression profiling of the response of Streptococcus pneumoniae to penicillin

Abstract

Altered expression of these genes reflects a protective response to perturbation of the bacterial cell wall by penicillin. Such genes may represent potential therapeutic targets for enhancing the activity of penicillin against this organism and provide insight into novel mechanisms of penicillin resistance.

The StkP/PhpP Signaling Couple inStreptococcus pneumoniae: Cellular Organization and Physiological Characterization

“…This observation is reminiscent of results obtained in Enterococcus faecalis, suggesting a role for the serine-threonine kinase in the response to cell wall stress (24). In S. pneumoniae, downregulation of several genes, including competence genes, was observed in cultures containing sublethal concentrations of penicillin, indicating that periplasmic signals may control competence (37). We postulate that StkP activity might allow the entry of "periplasmic signals" into the competence regulatory network, culminating in a competence trigger.…”

Antibiotic Modulation of the Plasminogen Binding Ability of Viridans Group Streptococci

“…Genes involved in DNA repair and the preservation of genome integrity were upregulated in S. aureus in response to fluoroquinolone sub-MICs (19). Similar findings were reported for S. pneumoniae, in which four genes involved in DNA metabolism and nine playing a role in energy metabolism were upregulated as a result of exposure to penicillin at a sub-MIC (24). These results support the observations previously made in which conservation of genes with core functions appears to be a general bacterial stress reaction, while modulation of genes involved in virulence through antibiotic exposure is dependent upon specific regulatory networks which lead to strainspecific responses (34).…”

“…Additionally, exposure of S. intermedius to ampicillin, ciprofloxacin, or tetracycline sub-MICs leads to en- hanced biofilm formation due to a significant increase in the expression of the luxS gene (1). Similarly, this gene was also induced in S. pneumoniae by exposure to penicillin (24).…”

“…Indeed, the presence of suboptimal antimicrobial concentrations has been demonstrated to modulate the expression of housekeeping genes involved in energy metabolism, as well as genes encoding toxins and adhesins of Staphylococcus aureus, Streptococcus intermedius, and S. pneumoniae (24,25,29). Characterization of ␣-enolase and GAPDH gene expression and phenotypic analysis of the plasminogen binding ability of VGS, as a result of the presence of antibiotic sub-MICs, may aid in the elucidation of the mechanisms involved in the response of these organisms to the antimicrobials commonly used in the management of streptococcal endocarditis.…”

Kinetic Characterization of the WalRKSpn(VicRK) Two-Component System ofStreptococcus pneumoniae: Dependence of WalKSpn(VicK) Phosphatase Activity on Its PAS Domain

“…Recent global transcription analyses suggest that it may also respond to cell wall stresses, such as antibiotic addition (22,38,68). In Bacillus and Staphylococcus species, both the WalR (YycF) response regulator and the WalK (YycG) histidine kinase are essential in that they cannot be depleted (20,23,53).…”