Phospholipid synthesis in Borrelia burgdorferi: BB0249 and BB0721 encode functional phosphatidylcholine synthase and phosphatidylglycerolphosphate synthase proteins

Microbiology ◽  
2004 ◽  
Vol 150 (2) ◽  
pp. 391-397 ◽  
Author(s):  
Xing-Guo Wang ◽  
Joanna P. Scagliotti ◽  
Linden T. Hu
Keyword(s):  
Borrelia Burgdorferi ◽  
Sinorhizobium Meliloti ◽  
Biosynthetic Pathways ◽  
Phospholipid Synthesis ◽  
Membrane Phospholipids ◽  
Bacterial Membranes ◽  
E Coli ◽  
Methylation Pathway ◽  
And Function

Phospholipids are an important component of bacterial membranes. Borrelia burgdorferi differs from many other bacteria in that it contains only two major membrane phospholipids: phosphatidylglycerol (PG) and phosphatidylcholine (PC). B. burgdorferi appears to lack enzymes required for synthesis of PC through the well-described methylation pathway. However, B. burgdorferi does contain a gene (BB0249) with significant identity to a recently described phosphatidylcholine synthase gene (pcs) of Sinorhizobium meliloti. B. burgdorferi also contains a gene (BB0721) with significant identity to the gene (pgs) encoding phosphatidylglycerolphosphate synthase, an enzyme in the synthetic pathway of PG. Activity of BB0249 was confirmed by cloning the gene into Escherichia coli, which does not produce PC. Transformation with a plasmid carrying BB0249 resulted in production of PC by E. coli, but only in the presence of exogenously supplied choline, as would be predicted for a Pcs. Because loss of Pgs activity is lethal to E. coli, activity of BB0721 was confirmed by the ability of BB0721 to complement an E. coli Pgs− mutant. A plasmid containing BB0721 was transformed into a Pgs− mutant of E. coli containing a copy of the native gene on a temperature-regulated plasmid. The temperature-regulated plasmid was exchanged for a plasmid containing BB0721 and it was shown that BB0721 was able to replace the lost Pgs function and restore bacterial growth. This study has established the existence and function of two critical enzymes in the synthesis of PC and PG in B. burgdorferi. Understanding of the biosynthetic pathways of PC and PG in B. burgdorferi is the first step in delineating the role of these phospholipids in the pathogenesis of Lyme disease.

Pathways for phosphatidylcholine biosynthesis in bacteria

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3461-3471 ◽  
Author(s):  
Fernando Martínez-Morales ◽  
Max Schobert ◽  
Isabel M. López-Lara ◽  
Otto Geiger
Keyword(s):  
Borrelia Burgdorferi ◽  
Legionella Pneumophila ◽  
Bradyrhizobium Japonicum ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Brucella Melitensis ◽  
Membrane Lipid ◽  
Mesorhizobium Loti ◽  
Methylation Pathway ◽  
Phosphatidylcholine Biosynthesis

Phosphatidylcholine (PC) is the major membrane-forming phospholipid in eukaryotes with important structural and signalling functions. Although many prokaryotes lack PC, it can be found in significant amounts in membranes of rather diverse bacteria. Two pathways for PC biosynthesis are known in bacteria, the methylation pathway and the phosphatidylcholine synthase (PCS) pathway. In the methylation pathway, phosphatidylethanolamine is methylated three times to yield PC, in reactions catalysed by one or several phospholipid N-methyltransferases (PMTs). In the PCS pathway, choline is condensed directly with CDP-diacylglyceride to form PC in a reaction catalysed by PCS. Using cell-free extracts, it was demonstrated that Sinorhizobium meliloti, Agrobacterium tumefaciens, Rhizobium leguminosarum, Bradyrhizobium japonicum, Mesorhizobium loti and Legionella pneumophila have both PMT and PCS activities. In addition, Rhodobacter sphaeroides has PMT activity and Brucella melitensis, Pseudomonas aeruginosa and Borrelia burgdorferi have PCS activities. Genes from M. loti and L. pneumophila encoding a Pmt or a Pcs activity and the genes from P. aeruginosa and Borrelia burgdorferi responsible for Pcs activity have been identified. Based on these functional assignments and on genomic data, one might predict that if bacteria contain PC as a membrane lipid, they usually possess both bacterial pathways for PC biosynthesis. However, important pathogens such as Brucella melitensis, P. aeruginosa and Borrelia burgdorferi seem to be exceptional as they possess only the PCS pathway for PC formation.

Critical Role of Zinc Ion on E. coli Glutamyl-Queuosine-tRNAAsp Synthetase (Glu-Q-RS) Structure and Function

2014 ◽  
Vol 33 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Sutapa Ray ◽  
Victor Banerjee ◽  
Mickael Blaise ◽  
Baisakhi Banerjee ◽  
Kali Pada Das ◽  
...  
Keyword(s):  
Critical Role ◽  
Zinc Ion ◽  
Structure And Function ◽  
E Coli ◽  
And Function

scholarly journals Functional Properties of Borrelia burgdorferi recA

2004 ◽  
Vol 186 (8) ◽  
pp. 2275-2280 ◽  
Author(s):  
Dionysios Liveris ◽  
Vishwaroop Mulay ◽  
Ira Schwartz
Keyword(s):  
Gene Expression ◽  
Borrelia Burgdorferi ◽  
Uv Irradiation ◽  
Reca Protein ◽  
Primary Role ◽  
Rapid Loss ◽  
E Coli ◽  
Uv Dose ◽  
Null Mutants

ABSTRACT Functions of the Borrelia burgdorferi RecA protein were investigated in Escherichia coli recA null mutants. Complementation with B. burgdorferi recA increased survival of E. coli recA mutants by 3 orders of magnitude at a UV dose of 2,000 μJ/cm2. The viability at this UV dose was about 10% that provided by the homologous recA gene. Expression of B. burgdorferi recA resulted in survival of E. coli at levels of mitomycin C that were lethal to noncomplemented hosts. B. burgdorferi RecA was as effective as E. coli RecA in mediating homologous recombination in E. coli. Furthermore, E. coli λ phage lysogens complemented with B. burgdorferi recA produced phage even in the absence of UV irradiation. The level of phage induction was 55-fold higher than the level in cells complemented with the homologous recA gene, suggesting that B. burgdorferi RecA may possess an enhanced coprotease activity. This study indicates that B. burgdorferi RecA mediates the same functions in E. coli as the homologous E. coli protein mediates. However, the rapid loss of viability and the absence of induction in recA expression after UV irradiation in B. burgdorferi suggest that recA is not involved in the repair of UV-induced damage in B. burgdorferi. The primary role of RecA in B. burgdorferi is likely to be a role in some aspect of recombination.

scholarly journals The role of Saccharomyces cerevisiae Met1p and Met8p in sirohaem and cobalamin biosynthesis

1999 ◽  
Vol 338 (3) ◽  
pp. 701-708 ◽  
Author(s):  
Evelyne RAUX ◽  
Treasa McVEIGH ◽  
Sarah E. PETERS ◽  
Thomas LEUSTEK ◽  
Martin J. WARREN
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Biosynthetic Pathways ◽  
Subtle Difference ◽  
Pseudomonas Denitrificans ◽  
E Coli ◽  
His Tag ◽  
Cobalamin Biosynthesis

MET1 and MET8 mutants of Saccharomyces cerevisiae can be complemented by Salmonella typhimurium cysG, indicating that the genes are involved in the transformation of uroporphyrinogen III into sirohaem. In the present study, we have demonstrated complementation of defined cysG mutants of Sal. typhimurium and Escherichia coli, with either MET1 or MET8 cloned in tandem with Pseudomonas denitrificans cobA. The conclusion drawn from these experiments is that MET1 encodes the S-adenosyl-l-methionine uroporphyrinogen III transmethylase activity, and MET8 encodes the dehydrogenase and chelatase activities (all three functions are encoded by Sal. typhimurium and E. coli cysG). MET8 was further cloned into pET14b to allow expression of the protein with an N-terminal His-tag. After purification, the functions of the His-tagged Met8p were studied in vitro by assay with precorrin-2 in the presence of NAD+ and Co2+. The results demonstrated that Met8p acts as a dehydrogenase and chelatase in the biosynthesis of sirohaem. Moreover, despite the fact that S. cerevisiae does not make cobalamins de novo, we have shown also that MET8 is able to complement cobalamin cobaltochelatase mutants and have revealed a subtle difference in the early stages of the anaerobic cobalamin biosynthetic pathways between Sal. typhimurium and Bacillus megaterium.

scholarly journals Borrelia burgdorferi ftsZ Plays a Role in Cell Division

2006 ◽  
Vol 188 (5) ◽  
pp. 1969-1978 ◽  
Author(s):  
Lydia Dubytska ◽  
Henry P. Godfrey ◽  
Felipe C. Cabello
Keyword(s):  
Cell Division ◽  
Borrelia Burgdorferi ◽  
Leading Edge ◽  
Loss Of Function ◽  
Chromosomal Dna ◽  
Lethal Mutant ◽  
E Coli ◽  
Its Gene ◽  
Conditional Lethal Mutant

ABSTRACT ftsZ is essential for cell division in many microorganisms. In Escherichia coli and Bacillus subtilis, FtsZ plays a role in ring formation at the leading edge of the cell division septum. An ftsZ homologue is present in the Borrelia burgdorferi genome (ftsZBbu ). Its gene product (FtsZBbu) is strongly homologous to other bacterial FtsZ proteins, but its function has not been established. Because loss-of-function mutants of ftsZBbu might be lethal, the tetR/tetO system was adapted for regulated control of this gene in B. burgdorferi. Sixty-two nucleotides of an ftsZBbu antisense DNA sequence under the control of a tetracycline-responsive modified hybrid borrelial promoter were cloned into pKFSS1. This construct was electroporated into a B. burgdorferi host strain carrying a chromosomally located tetR under the control of the B. burgdorferi flaB promoter. After induction by anhydrotetracycline, expression of antisense ftsZ RNA resulted in generation of filamentous B. burgdorferi that were unable to divide and grew more slowly than uninduced cells. To determine whether FtsZBbu could interfere with the function of E. coli FtsZ, ftsZBbu was amplified from chromosomal DNA and placed under the control of the tetracycline-regulated hybrid promoter. After introduction of the construct into E. coli and induction with anhydrotetracycline, overexpression of ftsZBbu generated a filamentous phenotype. This suggested interference of ftsZBbu with E. coli FtsZ function and confirmed the role of ftsZBbu in cell division. This is the first report of the generation of a B. burgdorferi conditional lethal mutant equivalent by tetracycline-controlled expression of antisense RNA.

scholarly journals The biosynthetic pathway of ubiquinone contributes to pathogenicity of Francisella

2021 ◽  
Author(s):  
Katayoun Kazemzadeh ◽  
Mahmoud Hajj Chehade ◽  
Gautier Hourdoir ◽  
Camille Dorothée Brunet ◽  
Yvan Caspar ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Biosynthetic Pathway ◽  
Galleria Mellonella ◽  
Competitive Inhibitor ◽  
Strictly Aerobic ◽  
Biosynthetic Pathways ◽  
Francisella Novicida ◽  
E Coli ◽  
Causative Bacterium

Francisella tularensis is the causative agent of tularemia. Because of its extreme infectivity and high mortality rate, this pathogen was classified as a biothreat agent. Francisella spp are strict aerobe and ubiquinone (UQ) has been previously identified in these bacteria. While the UQ biosynthetic pathways were extensively studied in Escherichia coli allowing the identification of fifteen Ubi-proteins to date, little is known about Francisella spp. In this study, and using Francisella novicida as a surrogate organism, we first identified UQ 8 as the major quinone found in the membranes of this bacterium. Then, we characterized the UQ biosynthetic pathway in F. novicida using a combination of bioinformatics, genetics and biochemical approaches. Our analysis disclosed the presence in Francisella of ten putative Ubi-proteins and we confirmed eight of them by heterologous complementation in E. coli . The UQ biosynthetic pathways from F. novicida and E. coli share a similar pattern. However, differences were highlighted: the decarboxylase remains unidentified in Francisella spp and homologs of the Ubi-proteins involved in the O 2 -independent UQ pathway are not present. This is in agreement with the strictly aerobic niche of this bacterium. Then, via two approaches, i.e. the use of an inhibitor (3-amino-4-hydroxybenzoic acid) and a transposon mutant, which both strongly impair the synthesis of UQ, we demonstrated that UQ is essential for the growth of F. novicida in a respiratory medium and contributes to its pathogenicity in Galleria mellonella used as an alternative animal model. Importance Francisella tularensis is the causative bacterium of tularemia and is classified as a biothreat agent. Using multidisciplinary approaches, we investigated the ubiquinone (UQ) biosynthetic pathway that operates in F. novicida used as a surrogate. We showed that UQ 8 is the major quinone identified in the membranes of Francisella novicida . We identified a new competitive inhibitor, which strongly decreased the biosynthesis of UQ. Our demonstration of the crucial role of UQ for the respiratory metabolism of F. novicida and for the involving in its pathogenicity in the Galleria mellonella model should stimulate the search for selective inhibitors of bacterial UQ biosynthesis.

scholarly journals Role of oxyR from Sinorhizobium meliloti in Regulating the Expression of Catalases

2005 ◽  
Vol 37 (6) ◽  
pp. 421-428 ◽  
Author(s):  
Li Luo ◽  
Ming-Sheng Qi ◽  
Shi-Yi Yao ◽  
Hai-Ping Cheng ◽  
Jia-Bi Zhu ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Wild Type Strain ◽  
Reduced Form ◽  
Insertion Mutant ◽  
Transcriptional Level ◽  
Oxygen Species ◽  
E Coli ◽  
Catalase Peroxidase

AbstractThe process of symbiotic nitrogen fixation results in the generation of reactive oxygen species such as the superoxide anion (O2-) and hydrogen peroxide (H2O2). The response of rhizobia to these toxic oxygen species is an important factor in nodulation and nitrogen fixation. In Sinorhizobium meliloti, one oxyR homologue and three catalase genes, katA, katB, and katC were detected by sequence analysis. This oxyR gene is located next to and divergently from katA on the chromosome. To investigate the possible roles of oxyR in regulating the expression of catalases at the transcriptional level in S. meliloti, an insertion mutant of this gene was constructed. The mutant was more sensitive and less adaptive to H2O2 than the wild type strain, and total catalase/peroxidase activity was reduced approximately fourfold with the OxyR mutation relative to controls. The activities of KatA and KatB and the expression of katA::lacZ and katB::lacZ promoter fusions were increased in the mutant strain compared with the parental strain grown in the absence of H2O2, indicating that katA and katB are repressed by OxyR. However, when exposed to H2O2, katA expression was also increased in both S. meliloti and Escherichia coli. When exposed to H2O2, OxyR is converted from a reduced to an oxidized form in E. coli. We concluded that the reduced form of OxyR functions as a repressor of katA and katB expression. Thus, in the presence of H2O2, reduced OxyR is converted to the oxidized form of OxyR that then results in increased katA expression. We further showed that oxyR expression is autoregulated via negative feedback.

scholarly journals Expression of the Streptomyces coelicolor SoxR Regulon Is Intimately Linked with Actinorhodin Production

2010 ◽  
Vol 192 (24) ◽  
pp. 6428-6438 ◽  
Author(s):  
Rica Dela Cruz ◽  
Yang Gao ◽  
Sahitya Penumetcha ◽  
Rebecca Sheplock ◽  
Katherine Weng ◽  
...  
Keyword(s):  
Streptomyces Coelicolor ◽  
Enteric Bacteria ◽  
Ecological Niches ◽  
Active Metabolites ◽  
E Coli ◽  
Redox Active ◽  
Tailoring Enzymes ◽  
And Function ◽  
Active Precursor

ABSTRACT The [2Fe-2S]-containing transcription factor SoxR is conserved in diverse bacteria. SoxR is traditionally known as the regulator of a global oxidative stress response in Escherichia coli, but recent studies suggest that this function may be restricted to enteric bacteria. In the vast majority of nonenterics, SoxR is predicted to mediate a response to endogenously produced redox-active metabolites. We have examined the regulation and function of the SoxR regulon in the model antibiotic-producing filamentous bacterium Streptomyces coelicolor. Unlike the E. coli soxR deletion mutant, the S. coelicolor equivalent is not hypersensitive to oxidants, indicating that SoxR does not potentiate antioxidant defense in the latter. SoxR regulates five genes in S. coelicolor, including those encoding a putative ABC transporter, two oxidoreductases, a monooxygenase, and a possible NAD-dependent epimerase/dehydratase. Expression of these genes depends on the production of the benzochromanequinone antibiotic actinorhodin and requires intact [2Fe-2S] clusters in SoxR. These data indicate that actinorhodin, or a redox-active precursor, modulates SoxR activity in S. coelicolor to stimulate the production of a membrane transporter and proteins with homology to actinorhodin-tailoring enzymes. While the role of SoxR in S. coelicolor remains under investigation, these studies support the notion that SoxR has been adapted to perform distinct physiological functions to serve the needs of organisms that occupy different ecological niches and face different environmental challenges.

scholarly journals Structure and function of bacteriophage CBA120 ORF211 (TSP2), the determinant of phage specificity towards E. coli O157:H7

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Julia Greenfield ◽  
Xiaoran Shang ◽  
Heng Luo ◽  
Yan Zhou ◽  
Sara B. Linden ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure And Function ◽  
Acid Base ◽  
E Coli ◽  
Close Proximity ◽  
Catalytic Role ◽  
And Function ◽  
Branched Structure ◽  
Partner Proteins

Abstract The genome of Escherichia coli O157:H7 bacteriophage vB_EcoM_CBA120 encodes four distinct tailspike proteins (TSPs). The four TSPs, TSP1-4, attach to the phage baseplate forming a branched structure. We report the 1.9 Å resolution crystal structure of TSP2 (ORF211), the TSP that confers phage specificity towards E. coli O157:H7. The structure shows that the N-terminal 168 residues involved in TSPs complex assembly are disordered in the absence of partner proteins. The ensuing head domain contains only the first of two fold modules seen in other phage vB_EcoM_CBA120 TSPs. The catalytic site resides in a cleft at the interface between adjacent trimer subunits, where Asp506, Glu568, and Asp571 are located in close proximity. Replacement of Asp506 and Asp571 for alanine residues abolishes enzyme activity, thus identifying the acid/base catalytic machinery. However, activity remains intact when Asp506 and Asp571 are mutated into asparagine residues. Analysis of additional site-directed mutants in the background of the D506N:D571N mutant suggests engagement of an alternative catalytic apparatus comprising Glu568 and Tyr623. Finally, we demonstrate the catalytic role of two interacting glutamate residues of TSP1, located in a cleft between two trimer subunits, Glu456 and Glu483, underscoring the diversity of the catalytic apparatus employed by phage vB_EcoM_CBA120 TSPs.

scholarly journals Structure and function of the hypochlorous acid–induced flavoprotein RclA from Escherichia coli

2020 ◽  
Vol 295 (10) ◽  
pp. 3202-3212 ◽  
Author(s):  
Yeongjin Baek ◽  
Jinwoo Kim ◽  
Jinsook Ahn ◽  
Inseong Jo ◽  
Seokho Hong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hypochlorous Acid ◽  
Copper Cation ◽  
Cysteine Residues ◽  
E Coli ◽  
Oxygen Levels ◽  
Microbial Invasion ◽  
And Function

In response to microbial invasion, the animal immune system generates hypochlorous acid (HOCl) that kills microorganisms in the oxidative burst. HOCl toxicity is amplified in the phagosome through import of the copper cation (Cu2+). In Escherichia coli and Salmonella, the transcriptional regulator RclR senses HOCl stress and induces expression of the RclA, -B, and -C proteins involved in bacterial defenses against oxidative stress. However, the structures and biochemical roles of the Rcl proteins remain to be elucidated. In this study, we first examined the role of the flavoprotein disulfide reductase (FDR) RclA in the survival of Salmonella in macrophage phagosomes, finding that RclA promotes Salmonella survival in macrophage vacuoles containing sublethal HOCl levels. To clarify the molecular mechanism, we determined the crystal structure of RclA from E. coli at 2.9 Å resolution. This analysis revealed that the structure of homodimeric RclA is similar to those of typical FDRs, exhibiting two conserved cysteine residues near the flavin ring of the cofactor flavin adenine dinucleotide (FAD). Of note, we observed that Cu2+ accelerated RclA-mediated oxidation of NADH, leading to a lowering of oxygen levels in vitro. Compared with the RclA WT enzyme, substitution of the conserved cysteine residues lowered the specificity to Cu2+ or substantially increased the production of superoxide anion in the absence of Cu2+. We conclude that RclA-mediated lowering of oxygen levels could contribute to the inhibition of oxidative bursts in phagosomes. Our study sheds light on the molecular basis for how bacteria can survive HOCl stress in macrophages.

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