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| Status |
Public on Sep 29, 2009 |
| Title |
Capsule Mediates the Cell Shape of pcsB Mutants in Serotype 2 Streptococcus pneumoniae |
| Organism |
Streptococcus pneumoniae |
| Experiment type |
Expression profiling by array
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| Summary |
PcsB is a protein of unknown function that plays a critical role in cell division in Streptococcus pneumoniae and other ovococcus species of Streptococcus. We constructed isogenic sets of mutants expressing different amounts of PcsB in laboratory strain R6 and virulent serotype 2 strain D39 to evaluate its cellular roles. Insertion mutagenesis in parent and pcsB+ merodiploid strains indicated that pcsB is essential in serotype 2 S. pneumoniae. Quantitative Western blotting of wild-type and epitope-tagged PcsB showed that all PcsB was processed into cell-associated and secreted forms of the same molecular mass. These analyses showed that PcsB bound to cells is present in relatively low amounts of only ≈ 300 molecules per cell. Controlled expression and complementation experiments indicated that there was a causative relationship between the severity of defects in cell division and decreasing PcsB amount. These experiments also indicated that perturbations of expression of the upstream mreCD genes did not contribute to the cell division defects of pcsB mutants and that mreCD could readily be deleted in these strains. Unexpectedly, the defects in cell division and cell shape in pcsB mutants or other mutants defective in cell wall biosynthesis, such as dacA, were strongly influenced by capsule. Underexpression of PcsB did not result in changes in the amounts or composition of lactoyl-muropeptides, which were markedly different in the R6 and D39 strains, and there was no correlation between decreased PcsB amount and sensitivity to penicillin. Finally, microarray analyses indicated that underexpression of PcsB may generate a signal that increases expression of the VicRK regulon, which includes pcsB.
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| Overall design |
Four independent hybridizations using independent RNA preparations from the strain IU1533 (reference strain) and strain IU1979 (a strain with decreased expression of PcsB protein) were performed. Dye swap was performed with the reference strain labeled with Cy3 in two hybridizations and Cy5 in the other two hybridizations.
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| Contributor(s) |
Barendt SM, Land AD, Sham L, Ng W, Tsui HT, Arnold RJ, Winkler ME |
| Citation(s) |
19270090 |
| |
| Submission date |
Oct 07, 2008 |
| Last update date |
Mar 20, 2012 |
| Contact name |
Ho-Ching Tiffany Tsui |
| E-mail(s) |
[email protected]
|
| Phone |
(812)856-1781
|
| Organization name |
Indiana University
|
| Department |
Biology
|
| Street address |
1001 E. Third St.
|
| City |
Bloomington |
| State/province |
IN |
| ZIP/Postal code |
47401 |
| Country |
USA |
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| Platforms (1) |
| GPL536 |
MWG Streptococcus pneumoniae Array |
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| Samples (4)
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| Relations |
| BioProject |
PRJNA109941 |
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