Positive Correlation between Tyrosine Phosphorylation of CpsD and Capsular Polysaccharide Production inStreptococcus pneumoniae

Abstract

CpsA, CpsB, CpsC, and CpsD are part of a tyrosine phosphorylation regulatory system involved in modulation of capsule synthesis in Streptococcus pneumoniae and many other gram-positive and gram-negative bacteria. Using an immunoblotting technique, we observed distinct laddering patterns of S. pneumoniae capsular polysaccharides of various serotypes and found that transfer of the polymer from the membrane to the cell wall was independent of size. Deletion of cps2A, cps2B, cps2C, or cps2D in the serotype 2 strain D39 did not affect the ability to transfer capsule to the cell wall. Deletion of cps2C or cps2D, which encode two domains of an autophosphorylating tyrosine kinase, resulted in the production of only short-chain polymers. The function of Cps2A is unknown, and the polymer laddering pattern of the cps2A deletion mutants appeared similar to that of the parent, although the total amount of capsule was decreased. Loss of Cps2B, a tyrosine phosphatase and a kinase inhibitor, resulted in an increase in capsule amount and a normal ladder pattern. However, Cps2B mutants exhibited reduced virulence following intravenous inoculation of mice and were unable to colonize the nasopharynx, suggesting a diminished capacity to sense or respond to these environments. In D39 and its isogenic mutants, the amounts of capsule and tyrosine-phosphorylated Cps2D (Cps2DϳP) correlated directly. In contrast, restoration of type 2 capsule production followed by deletion of cps2B in Rx1, a laboratory passaged D39 derivative containing multiple uncharacterized mutations, resulted in decreased capsule amounts but no alteration in Cps2DϳP levels. Thus, a factor outside the capsule locus, which is either missing or defective in the Rx1 background, is important in the control of capsule synthesis.

In vitro expression of the first capsule gene of Streptococcus pneumoniae, cpsA, is associated with serotype-specific colonization prevalence and invasiveness

“…Control of capsule expression is not well understood, except for the case of switching off capsule expression entirely by spontaneous sequence duplications or mutations in capsule genes (Waite et al, 2001(Waite et al, , 2003Arrecubieta et al, 1994), or apparent replacement of capsule genes with novel aliB-like ORFs (Hathaway et al, 2004). However, in strains with a complete capsule operon, a role for tyrosine phosphorylation of CpsD, the product of the fourth capsule operon gene, in regulation of capsular polysaccharide production has been proposed (Bender et al, 2003). In this study the role of transcription of the capsule operon was investigated.…”

Comparative analysis of the exopolysaccharide biosynthesis gene clusters from four strains of Lactobacillus rhamnosus

“…Given the similarity in predicted protein products of these three genes with other gene products involved in chain-length determination, the model of regulating EPS biosynthesis at the post-transcriptional level described for S. pneumoniae (Bender et al, 2003;Morona et al, 2000Morona et al, , 2003 is probably applicable to a certain degree to Lb. rhamnosus as well.…”

Wzy-Dependent Bacterial Capsules as Potential Drug Targets

“…Bender et al [91] saw a slight increase in the S. pneumoniae strain D39. This has led to confusion as to whether phosphorylation of CpsD is associated with a positive or negative effect on capsule expression.…”