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

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Introduction Regulation of nitrogen metabolism in bacteria is closely connected with the intracellular levels of glutamine and glutamate, the main nitrogen donors in the cell. Glutamine is formed from glutamate and ammonium by glutamine synthetase (GlnA), which is a major way for the cell to assimilate ammonium. Glutamate can be formed either by glutamate dehydrogenase from 2-oxoglutarate and ammonium, or by glutamate synthase, which converts glutamine and 2-oxoglutarate into two molecules of glutamate. Several studies indicate that nitrogen metabolism, especially glutamine metabolism, is important for the virulence of various bacterial pathogens (24, 43, 45)Signature-tagged mutagenesis screens suggest that genes involved in glutamine metabolism, glnQ and glnA, are likely to play a role in the virulence of S. pneumoniae as well (18, 28, 36). However, so far, glutamine metabolism and the way in which it is regulated have not been studied in this human pathogen. In the well-characterized Gram-positive bacterium Bacillus subtilis, regulation of nitrogen metabolism is carried out mainly by CodY, GlnR and TnrA (13). The latter two are members of the MerR family of regulators, and both recognize the same operator sequence: ‘5-TGTNAN7TNACA-3’. TnrA functions during growth on a poor nitrogen source, for example solely glutamate, when it activates or represses expression of various genes involved in nitrogen metabolism (5, 32, 41, 50, 53). GlnR represses its own operon glnRA (8), the ureABC operon (encoding urease) (7, 49) and tnrA (13) in the presence of a good nitrogen source, like glutamine. Genetic experiments have shown that genes regulated by GlnR and TnrA are constitutively expressed in a mutant of glnA (38-40, 50). An explanation for this observation came with the discovery that in vitro DNA-binding by TnrA is blocked by feedback-inhibited GlnA (52). Although it has been suggested that GlnA also controls the DNA-binding activity of GlnR, this has never been shown. In fact, B. subtilis GlnR has a high affinity for DNA on its own (8). Nitrogen Metabolism in S. pneumoniae B. subtilis CodY functions as a repressor of genes involved in nitrogen metabolism (20), but also of carbon and energy metabolism (22), motility (6) and competence development (31). In the lactic acid bacterium Lactococcus lactis, CodY represses genes of the proteolytic system and several amino acid transport and metabolism genes, amongst others gltA and gltD, which are involved in glutamate biosynthesis (11, 15, 16). Analysis of the S. pneumoniae R6 (19) and TIGR4 (44) genomes revealed that they contain genes encoding orthologs of GlnR and CodY, but not of TnrA. Furthermore, S. 123 123
Chapter 5 pneumoniae contains a putative ortholog of glnA, several predicted glutamine uptake systems and a predicted biosynthetic glutamate dehydrogenase (19, 44). In contrast to B. subtilis and L. lactis, a gene encoding glutamate synthase is not present. This suggests that S. pneumoniae has various ways to warrant sufficient cellular glutamine levels, either by uptake from the environment or by de novo synthesis. 124 124 In this study, we report on the important role of GlnR and GlnA in the regulation of glutamine and glutamate metabolism in S. pneumoniae, and present indications for a role of GlnR-targets in pneumococcal virulence.
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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
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Materiaals and Meethods Gene regula
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(Invitrogen), 0.2 mM aminoallyl dUT
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Isolation of pneumococcal RNA durin
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Resultss and Discuussion Gene regul
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Table 1. Genes regulated by RR09 in
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phosphofructokinase, and a fructose
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Figure 4. Expression of rlrA and rr
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correlated well with our in vitro m
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Figure 7. Bacterial loads in blood
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Acknowledgments This work was suppo
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10. Ibrahim, Y. M., A. R. Kerr, J.
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genome sequence of a virulent isola
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Gene regulation by RR09 in S. pneum
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Gene regulation by RR09 in S. pneum
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Table S4. Genes up- and downregulat
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Table S6. Genes up- and downregulat
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Chapter 3 Abstract 62 62 Previous s
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Chapter 3 between the wild-type and
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Chapter 3 S. pneumoniae TIGR4 by CS
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Chapter 3 performance liquid chroma
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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
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 126 and 127: Materials and Methods Nitrogen Meta
Page 128 and 129: TK136 D39 Δcps; Km R capsule-less
Page 130 and 131: gene from pORI28, was fused to the
Page 132 and 133: Construction of lacZ fusions Chromo
Page 134 and 135: Enzyme assays Cell-free extracts, u
Page 136 and 137: Reverse-transcriptase PCR RNA isola
Page 138 and 139: Table 3. Summary of transcriptome c
Page 140 and 141: effect caused by altered intracellu
Page 142 and 143: examine whether zwf is only transcr
Page 144 and 145: (http://www.bd.com/ds/technicalCent
Page 146 and 147: H6-GlnR alone at the concentration
Page 148 and 149: Discussion In this study, we charac
Page 150 and 151: Acknowledgements TK, JB and HB are
Page 152 and 153: 11. den Hengst, C. D., S. A. van Hi
Page 154 and 155: Nitrogen Metabolism in S. pneumonia
Page 156 and 157: 52. Wray, L. V., Jr., J. M. Zalieck
Page 158 and 159: CHAPTER 6 Site-specific contributio
Page 160 and 161: Introduction GlnR-regulon and pneum
Page 162 and 163: Materials and Methods Bacterial str
Page 164 and 165: eferred to as t=0. Bacteriology res
Page 166 and 167: Results GlnR-regulon and pneumococc
Page 168 and 169: Figure 3. Colonization model. Bacte
Page 170 and 171: GlnR-regulon and pneumococcal virul
Page 172 and 173: 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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