CpsR, a GntR family regulator, transcriptionally regulates capsular polysaccharide biosynthesis and governs bacterial virulence in Streptococcus pneumoniae

Abstract

Transcriptional regulation of capsule expression is critical for pneumococcal transition from carriage to infection, yet the underlying mechanism remains incompletely understood. Here, we describe the regulation of capsular polysaccharide, one of the most important pneumococcal virulence factor by a GntR family regulator, CpsR. Electrophoretic mobility-shift assays have shown the direct interaction between CpsR and the cps promoter (cpsp), and their interaction could be competitively interfered by glucose. DNase I footprinting assays localized the binding site to a region −146 to −114 base pairs relative to the transcriptional start site of the cps locus in S. pneumoniae D39. We found that CpsR negatively controlled the transcription of the cps locus and hence CPS production, which was confirmed by fine-tuning expression of CpsR in a ΔcpsR complemented strain. Increased expression of CpsR in complemented strain led to a decreased resistance to the whole-blood-mediated killing, suggesting a protective role for CpsR-cpsp interaction in the establishment of invasive infection. Finally, animal experiments showed that CpsR-cpsp interaction was necessary for both pneumococcal colonization and invasive infection. Taken together, our results provide a thorough insight into the regulation of capsule production mediated by CpsR and its important roles in pneumococcal pathogenesis.

Deletion of the Zinc Transporter Lipoprotein AdcAII Causes Hyperencapsulation of Streptococcus pneumoniae Associated with Distinct Alleles of the Type I Restriction-Modification System

“…The close linkage to adcAII suggests a role for disruption of zinc utilization, yet the hyperencapsulated phenotype did not occur with mutation of the other S. pneumoniae zinc uptake lipoprotein gene adcA (19) and was not affected by zinc availability. Combined deletion of adcA and adcAII was also not associated with the hyperencapsulated phenotype, but the double mutation had major effects on S. pneumoniae (37), and RegM (38), as well as the conserved 5= cpsABCD (also termed wzg, wzh, wzd, and wze) genes of the cps locus (39)(40)(41). Two S. pneumoniae quorum-sensing systems (LuxS/AI-2 and the Rgg/small hydrophobic peptide system) increase capsule thickness (42)(43)(44), which can also be regulated independently of gene transcription by the supply of capsule monosaccharide precursors (45) or by increased capsule shedding mediated by LytA (12).…”

Capsule Type and Amount Affect Shedding and Transmission of Streptococcus pneumoniae

“…The cps promoter region has considerable sequence variability among pneumococcal isolates and impacts levels of CPS expression ( 28 – 30 ). To examine the contribution of CPS amount in shedding, we tested constructs of the same type that express different levels of CPS.…”

SPD_1495 Contributes to Capsular Polysaccharide Synthesis and Virulence in Streptococcus pneumoniae

“…The proteomic data and detection of capsule showed that the formation of CPS was negatively regulated by SPD_1495. In S. pneumoniae, the cps gene cluster is mainly responsible for the CPS biosynthesis (19). We speculated that SPD_1495 may regulate the expression of the cps gene cluster via interaction with the CPS operon.…”

“…(10,(13)(14)(15). Further, several possible transcriptional regulators of the cps locus, such as RegM (16), ComX (17), CopY (18), CpsR (19), GlnR (20), RitR (21), and ComE (9), have also been reported to regulate CPS formation. In particular, ComE exists in S. pneumoniae in nonphosphorylated and phosphorylated forms, and only the latter form can negatively regulate the expression of the cps gene cluster via interaction with the upstream promoter of cps in vivo (9).…”