Gene regulation in Streptococcus pneumoniae - RePub - Erasmus ...

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PsaR and pneumococcal virulence mutant was observed, which is in agreement with our results. Johnston et al. (2006) reported that during lung infection the psaR-mutant had significantly lower bacterial loads than the wild-type after 7 days of infection. However, in our pneumonia model, we observed higher bacterial loads in D39ΔpsaR -infected mice at the beginning of the experiment (the first 12h). The TIGR4 ΔpsaR–infected mice had significantly lower bacterial loads at 24h only. Taken together, we did not observe any clear role for PsaR during lung infection in our study. Upon intravenous infection, we observed the most pronounced effect of deletion of psaR. The psaR-mutant was attenuated at the early stages of blood infection. In line with this, PsaR was identified by a large STM study to be required for full virulence of a serotype 3 strain in a bacteremia model of infection after 24h of infection (36). Importantly, for D39 no significant difference was observed in our model at 30h post-infection. This indicates that in the first 24h PsaR-regulation is required for adaptation to the blood. Furthermore, in D39, survival times of wild-type and ΔpsaR-infected mice were different, although this just reached statistical significance. In contrast, mice infected with TIGR4 wild-type and ΔpsaR did not exhibit any differences in the first 24h of experimental bacteremia, while after 36h they did. This indicates that in TIGR4, PsaR contributes to the later stages of bacteremia. However, since the TIGR4 wild-type was not able to cause infection as severe as D39, this contribution is considered to be marginal. Although we observed disturbed gene regulation in the D39 and TIGR4 mutants, in most infections models (described above) we did not observe large effects on virulence. A study performed on the pneumococcal carbohydrate regulator RegM showed that, even though deletion of a regulator does not necessarily lead to large differences in expression of known virulence genes, it can affect pneumococcal virulence (14). Conversely, a second study by Trombe and co-workers showed that deleting the global regulator RegR, does not dramatically affect virulence, but has a large effect on gene expression (7). It seems that the pneumococcus has several compensatory virulence pathways. Strain-specific contributions of genes encoding transcriptional regulators have been reported previously and complicate ascribing a general role for these genes in transcriptional control of their targets and their contribution to virulence (24, 40). PsaR directly controls the expression of a select group of genes individually important for virulence (psaBCA and rlrA) (28, 32). The observed differences in PsaR-regulated gene expression between D39 and TIGR4 might be the indirect effect of an unbalanced Mn 2+ -homeostasis, which suggests that physiological differences might reflect genetic differences present in these strains. A clear example of the genetic difference is the rlrA pathogenicity islet, which is strongly upregulated 79 79
Chapter 3 in TIGR4ΔpsaR. However, the genetic diversity between strains only varies as much as 10%, most of which can be attributed to the capsular genes (16, 35). In conclusion, PsaR does not contribute to colonization of S. pneumoniae, but it is involved in invasive disease where it has a strain-specific impact during both pneumonia and bacteremia. 80 80
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Gene regulation in Streptococcus pn
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Cover image by Duve van Boggelen (w
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Promotiecommissie Promotoren: Prof.
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CHAPTER 1 Introduction 7
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Introduction Figure 1. Infections c
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Interestingly, autolysis induced by
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histidine kinase is the sensor prot
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metabolism are often required for v
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egulatory systems, aiming to elucid
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11. Cockeran, R., A. J. Theron, H.
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33. Li, S., S. J. Kelly, E. Lamani,
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53. Romero, P., R. Lopez, and E. Ga
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CHAPTER 2 Regulation of gene expres
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Introduction Streptococcus pneumoni
Page 30 and 31: Materiaals and Meethods Gene regula
Page 32 and 33: (Invitrogen), 0.2 mM aminoallyl dUT
Page 34 and 35: Isolation of pneumococcal RNA durin
Page 36 and 37: Resultss and Discuussion Gene regul
Page 38 and 39: Table 1. Genes regulated by RR09 in
Page 40 and 41: phosphofructokinase, and a fructose
Page 42 and 43: Figure 4. Expression of rlrA and rr
Page 44 and 45: correlated well with our in vitro m
Page 46 and 47: Figure 7. Bacterial loads in blood
Page 48 and 49: Acknowledgments This work was suppo
Page 50 and 51: 10. Ibrahim, Y. M., A. R. Kerr, J.
Page 52 and 53: genome sequence of a virulent isola
Page 54 and 55: Gene regulation by RR09 in S. pneum
Page 56 and 57: Gene regulation by RR09 in S. pneum
Page 58 and 59: Table S4. Genes up- and downregulat
Page 60: Table S6. Genes up- and downregulat
Page 63 and 64: Chapter 3 Abstract 62 62 Previous s
Page 65 and 66: Chapter 3 between the wild-type and
Page 67 and 68: Chapter 3 S. pneumoniae TIGR4 by CS
Page 69 and 70: Chapter 3 performance liquid chroma
Page 71 and 72: Chapter 3 Results Transcriptional a
Page 73 and 74: Chapter 3 Table 3. Differentially e
Page 75 and 76: Chapter 3 Figure 2. Colonization mo
Page 77 and 78: Chapter 3 than the D39ΔpsaR-infect
Page 79: Chapter 3 effect was more severe fo
Page 83 and 84: Chapter 3 References 1. Adrian, P.
Page 85 and 86: Chapter 3 21. Hemsley, C., E. Joyce
Page 87 and 88: Chapter 3 40. McCluskey, J., J. Hin
Page 90 and 91: CHAPTER 4 CodY of Streptococcus pne
Page 92 and 93: Introduction Bacteria encounter var
Page 94 and 95: Materials and Methods Bacterial str
Page 96 and 97: Table 2. Oligonucleotide primers us
Page 98 and 99: The CodY regulon of S. pneumoniae I
Page 100 and 101: The CodY regulon of S. pneumoniae w
Page 102 and 103: Accession numbers The microarray da
Page 104 and 105: Table 3. Differentially expressed g
Page 106 and 107: Binding of CodY to target promoters
Page 108 and 109: The CodY regulon of S. pneumoniae E
Page 110 and 111: The CodY regulon of S. pneumoniae F
Page 112 and 113: Discussion CodY has been described
Page 114 and 115: levels of adherence in D39. Using a
Page 116 and 117: References The CodY regulon of S. p
Page 118 and 119: Glass. 2001. Genome of the bacteriu
Page 120 and 121: 40. Shivers, R. P., S. S. Dineen, a
Page 122 and 123: CHAPTER 5 Regulation of glutamine a
Page 124 and 125: Introduction Regulation of nitrogen
Page 126 and 127: Materials and Methods Nitrogen Meta
Page 128 and 129: TK136 D39 Δcps; Km R capsule-less
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gene from pORI28, was fused to the
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Construction of lacZ fusions Chromo
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Enzyme assays Cell-free extracts, u
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Reverse-transcriptase PCR RNA isola
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Table 3. Summary of transcriptome c
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effect caused by altered intracellu
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examine whether zwf is only transcr
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(http://www.bd.com/ds/technicalCent
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H6-GlnR alone at the concentration
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Discussion In this study, we charac
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Acknowledgements TK, JB and HB are
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11. den Hengst, C. D., S. A. van Hi
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Nitrogen Metabolism in S. pneumonia
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52. Wray, L. V., Jr., J. M. Zalieck
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CHAPTER 6 Site-specific contributio
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Introduction GlnR-regulon and pneum
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Materials and Methods Bacterial str
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eferred to as t=0. Bacteriology res
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Results GlnR-regulon and pneumococc
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Figure 3. Colonization model. Bacte
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GlnR-regulon and pneumococcal virul
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Table 2. Differentially expressed g
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Discussion The ability to adequatel
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The microarray data showed that pre
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Acknowledgments WTH is supported by
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12. Ibrahim, Y. M., A. R. Kerr, J.
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33. Zalieckas, J. M., L. V. Wray, J
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CHAPTER 7 Pneumococcal gene regulat
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Introduction Regulation of gene exp
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Gene regulation and metabolism in S
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makes it possible for the pneumococ
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A CcpA homologue exists in the pneu
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double mutant, suggesting direct re
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References Gene regulation and meta
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23. Kerr, A. R., P. V. Adrian, S. E
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45. Sonenshein, A. L. 2005. CodY, a
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CHAPTER 8 Summarizing discussion 20
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that the observed virulence phenoty
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CodY was found to be required for a
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References Summarizing discussion 1
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Summarizing discussion 21. Orihuela
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Samenvatting en discussie Curriculu
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Samenvatting en discussie kunnen ge
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Bevindingen die dit onderbouwen, we
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Curriculum Vitae Curriculum Vitae W
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Dankwoord Jeetje, dat het dan toch
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oekje en ik kijk uit naar de bijbeh
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