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

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Introduction PsaR and pneumococcal virulence Streptococcus pneumoniae encounters different environments during its life cycle: in most cases it inhabits the human nasopharynx where it resides asymptomatically, but it can also spread through the body, causing severe infections (5). What exactly triggers the pneumococcus to cause infections at these sites in the body is poorly understood. In response to environmental changes, the transcriptional program is likely to change, which is considered to be niche-specific and can result in expression of distinct virulence factors. Manganese ions (Mn 2+ ) are important for bacterial life, for instance serving as cofactors for metalloenzymes. The function of these metalloenzymes is widespread among bacterial cellular processes, such as glycolysis, gluconeogenesis, and oxidative stress defense (26). In pneumococcus, involvement of Mn 2+ in competence has also been described (12), but most studies have focused on its involvement in oxidative stress (25, 28, 39, 40, 42, 48). In the latter process, Mn 2+ serves as a cofactor for superoxide dismutase, an important enzyme that provides defense against superoxide radicals (3). As the concentration of manganese is much higher in saliva than in blood plasma (9), fluctuations in the amount of this trace element might serve as a trigger for expression of certain virulence factors. Various transcriptional regulators have been described for the pneumococcus (20) and several large scale mutagenesis studies have identified a role in virulence for these regulators (8, 18, 21, 36, 43). One of them is encoded by psaR, a transcriptional regulator responsive to Mn 2+ and negatively affecting the expression of the psa operon, pcpA, rlrA, and prtA (28, 32). Recently, the PsaR-binding sequence was identified in the promoter region of psaBCA, prtA, and pcpA, and a genome-wide screen for this binding sequence did not show any other putative targets (31). Moreover, it has been reported that regulation by PsaR is opposite in reaction to two cations, namely repression in high Mn 2+ and derepression in high Zn 2+ (32). The pcpA gene encodes a choline binding protein (46) and rlrA encodes a transcriptional regulator, which controls the expression of the rlrA pathogenicity islet (19). The psaBCA operon encodes the Psa permease that transports the cations Mn 2+ and Zn 2+ into the cell (12, 28, 29, 37, 39). The permease has been implicated in virulence and protection against pneumococcal infection (6, 47). Moreover, PsaA has been shown to bind to Ecadherin, a surface molecule of the host cells (2, 44, 45). PsaR homologues are found in other streptococci, where they regulate homologues of psaBCA and contribute to virulence (17, 27, 41). The role of PsaR in pneumococcal virulence has been investigated in an EF3030 (serotype 19F) genetic background (28). During seven days of colonization no difference 63 63
Chapter 3 between the wild-type and its isogenic psaR-mutant was observed, while after 7 days of lung infection, the psaR-mutant was significantly attenuated compared to the wild-type (28). 64 64 In this study, we examined the effect of the deletion of psaR on global gene and protein expression in two other pneumococcal strains, D39 (serotype 2) and TIGR4 (serotype 4) using transcriptomics and proteomics. Furthermore, we investigated the contribution of PsaR to pneumococcal virulence in three murine infection models representing the major phases in the life cycle of S. pneumoniae: colonization, pneumonia, and bacteremia.
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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
Page 14 and 15: histidine kinase is the sensor prot
Page 16 and 17: metabolism are often required for v
Page 18 and 19: egulatory systems, aiming to elucid
Page 20 and 21: 11. Cockeran, R., A. J. Theron, H.
Page 22 and 23: 33. Li, S., S. J. Kelly, E. Lamani,
Page 24 and 25: 53. Romero, P., R. Lopez, and E. Ga
Page 26 and 27: CHAPTER 2 Regulation of gene expres
Page 28 and 29: 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: Chapter 3 Abstract 62 62 Previous s
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 and 80: Chapter 3 effect was more severe fo
Page 81 and 82: Chapter 3 in TIGR4ΔpsaR. However,
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
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levels of adherence in D39. Using a
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References The CodY regulon of S. p
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Glass. 2001. Genome of the bacteriu
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40. Shivers, R. P., S. S. Dineen, a
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CHAPTER 5 Regulation of glutamine a
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Introduction Regulation of nitrogen
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Materials and Methods Nitrogen Meta
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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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