scholarly journals An Unexpected Role for the Periplasmic Phosphatase PhoN in the Salvage of B6 Vitamers in Salmonella enterica

2020 ◽  
Author(s):  
Huong N. Vu ◽  
Diana M. Downs
Keyword(s):  
Salmonella Enterica ◽  
De Novo ◽  
Active Form ◽  
Biologically Active ◽  
General Role ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Domains Of Life

Pyridoxal 5′-phosphate (PLP) is the biologically active form of vitamin B6 essential for cellular function in all domains of life. In many organisms, such as Salmonella enterica serovar Typhimurium and Escherichia coli, this cofactor can be synthesized de novo, or salvaged from B6 vitamers in the environment. Unexpectedly, S. enterica strains blocked in PLP biosynthesis were able to use exogenous PLP and pyridoxine 5′-phosphate (PNP) as the source of this required cofactor, while E. coli strains of the same genotype could not. Transposon mutagenesis found that phoN was essential for the salvage of PLP and PNP under the conditions tested. phoN encodes a class A nonspecific acid phosphatase (EC 3.1.3.2) that is transcriptionally regulated by the PhoPQ two-component system. The periplasmic location of PhoN was essential for PLP and PNP salvage, and in vitro assays confirmed PhoN has phosphatase activity with PLP and PNP as substrates. The data suggest that PhoN dephosphorylates B6 vitamers, after which they enter the cytoplasm and are phosphorylated by kinases of the canonical PLP salvage pathway. The connection of phoN with PhoPQ, and the broad specificity of the gene product suggests S. enterica is exploiting a moonlighting activity of PhoN for PLP salvage. IMPORTANCE Nutrient salvage is a strategy used by species across domains of life to conserve energy. Many organisms are unable to synthesize all required metabolites de novo and must rely exclusively on salvage. Others supplement de novo synthesis with the ability to salvage. This study identified an unexpected mechanism present in S. enterica that allows salvage of phosphorylated B6 vitamers. In vivo and in vitro data herein determined that the periplasmic phosphatase PhoN can facilitate the salvage of PLP and PNP. We suggest a mechanistic working model of PhoN-dependent utilization of PLP and PNP and discuss the general role of promiscuous phosphatases and kinases in organismal fitness.

scholarly journals Effect of Inactivation of degS on Salmonella enterica Serovar Typhimurium In Vitro and In Vivo

2005 ◽  
Vol 73 (1) ◽  
pp. 459-463 ◽  
Author(s):  
Gary Rowley ◽  
Andrew Stevenson ◽  
Jan Kormanec ◽  
Mark Roberts
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Alternative Pathways ◽  
E Coli ◽  
Mammalian Tissues ◽  
Serovar Typhimurium

ABSTRACT The alternative sigma factor (RpoE σE) enables Salmonella enterica serovar Typhimurium to adapt to stressful conditions, such as oxidative stress, nutrient deprivation, and growth in mammalian tissues. Infection of mice by Salmonella serovar Typhimurium also requires σE. In Escherichia coli, activation of the σE pathway is dependent on proteolysis of the anti-sigma factor RseA and is initiated by DegS. DegS is also important in order for E. coli to cause extraintestinal infection in mice. We constructed a degS mutant of the serovar Typhimurium strain SL1344 and compared its behavior in vitro and in vivo with those of its wild-type (WT) parent and an isogenic rpoE mutant. Unlike E. coli degS strains, the Salmonella serovar Typhimurium degS strain grew as well as the WT strain at 42°C. The degS mutant survived very poorly in murine macrophages in vitro and was highly attenuated compared with the WT strain for both the oral and parenteral routes of infection in mice. However, the degS mutant was not as attenuated as the serovar Typhimurium rpoE mutant: 100- to 1,000-fold more degS bacteria than rpoE bacteria were present in the livers and spleens of mice 24 h after intraperitoneal challenge. In most assays, the rpoE mutant was more severely affected than the degS mutant and a σE-dependent reporter gene was more active in the degS mutant than the rpoE strain. These findings indicate that degS is important for activation of the σE pathway in serovar Typhimurium but that alternative pathways for σE activation probably exist.

scholarly journals Delivery of the Immunosuppressive Antigen Salp15 to Antigen-Presenting Cells by Salmonella enterica Serovar Typhimurium aroA Mutants

2004 ◽  
Vol 72 (6) ◽  
pp. 3638-3642 ◽  
Author(s):  
Amir-Reza T. Motameni ◽  
Ignacio J. Juncadella ◽  
Shobana K. Ananthanarayanan ◽  
Michael N. Hedrick ◽  
Yvette Huet-Hudson ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Salmonella Enterica ◽  
Cell Activation ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Active Form ◽  
Antigen Presenting Cells ◽  
Serovar Typhimurium ◽  
Antigen Presenting

ABSTRACT A Salmonella enterica serovar Typhimurium aroA-deficient delivery system was used to target the immunosuppressive protein Salp15 to antigen-presenting cells. In vitro and in vivo infections with Salp15-containing Salmonella resulted in an impaired CD4+-T-cell activation, suggesting that the protein was produced by antigen-presenting cells in a physiologically active form.

scholarly journals Salmonella enterica Serovar Typhimurium RamA, Intracellular Oxidative Stress Response, and Bacterial Virulence

2004 ◽  
Vol 72 (2) ◽  
pp. 996-1003 ◽  
Author(s):  
Tahar van der Straaten ◽  
Laurence Zulianello ◽  
Angela van Diepen ◽  
Donald L. Granger ◽  
Riny Janssen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Salmonella Enterica ◽  
Raw 264.7 Cells ◽  
Virulence Determinants ◽  
Multidrug Resistance Gene ◽  
Bacterial Gene ◽  
E Coli ◽  
Serovar Typhimurium

ABSTRACT Escherichia coli and Salmonella enterica serovar Typhimurium have evolved genetic systems, such as the soxR/S and marA regulons, to detoxify reactive oxygen species, like superoxide, which are formed as by-products of metabolism. Superoxide also serves as a microbicidal effector mechanism of the host's phagocytes. Here, we investigate whether regulatory genes other than soxR/S and marA are active in response to oxidative stress in Salmonella and may function as virulence determinants. We identified a bacterial gene, which was designated ramA (342 bp) and mapped at 13.1 min on the Salmonella chromosome, that, when overexpressed on a plasmid in E. coli or Salmonella, confers a pleiotropic phenotype characterized by increased resistance to the redox-cycling agent menadione and to multiple unrelated antibiotics. The ramA gene is present in Salmonella serovars but is absent in E. coli. The gene product displays 37 to 52% homology to the transcriptional activators soxR/S and marA and 80 to 100% identity to a multidrug resistance gene in Klebsiella pneumoniae and Salmonella enterica serovar Paratyphi A. Although a ramA soxR/S double null mutant is highly susceptible to intracellular superoxide generated by menadione and displays decreased Mn-superoxide dismutase activity, intracellular survival of this mutant within macrophage-like RAW 264.7 cells and in vivo replication in the spleens in Ityr mice are not affected. We concluded that despite its role in the protective response of the bacteria to oxidative stress in vitro, the newly identified ramA gene, together with soxR/S, does not play a role in initial replication of Salmonella in the organs of mice.

scholarly journals Biologically Active Isoforms of CobB Sirtuin Deacetylase in Salmonella enterica and Erwinia amylovora

2010 ◽  
Vol 192 (23) ◽  
pp. 6200-6208 ◽  
Author(s):  
Alex C. Tucker ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Amino Acid ◽  
Salmonella Enterica ◽  
Cellular Localization ◽  
Erwinia Amylovora ◽  
Biologically Active ◽  
Transcription Start ◽  
Control Of Gene Expression ◽  
Domains Of Life

ABSTRACT Sirtuins are NAD+-dependent protein deacylases that are conserved in all domains of life and are involved in diverse cellular processes, including control of gene expression and central metabolism. Eukaryotic sirtuins have N-terminal extensions that have been linked to protein multimerization and cellular localization. Here the first evidence of sirtuin isoforms in bacteria is reported. The enterobacterium Salmonella enterica synthesizes two isoforms of CobB sirtuin, a shorter 236-amino-acid isoform (here CobBS) and a longer 273-amino-acid isoform (here CobBL). The N-terminal 37-amino-acid extension of CobBL is amphipathic, containing 18 basic amino acids (12 of which are Arg) and 13 hydrophobic ones; both isoforms were active in vivo and in vitro. Northern blot and transcription start site analyses revealed that cobB is primarily expressed as two monocistronic cobB mRNAs from two transcription start sites, one of which was mapped within the neighboring ycfX gene and the other of which was located within cobB. Additionally, a low-abundance ycfX-cobB bicistronic mRNA was observed which could encode up to three proteins (YcfX, CobBL, and CobBS). CobBL isoforms are common within the family Enterobacteriaceae, but species of the genus Erwinia (including the plant pathogen Erwinia amylovora) encode only the CobBL isoform. The CobBL isoform from E. amylovora restored growth of as S. enterica cobB mutant strain on low acetate.

scholarly journals Reassessment of the Late Steps of Coenzyme B12 Synthesis in Salmonella enterica: Evidence that Dephosphorylation of Adenosylcobalamin-5′-Phosphate by the CobC Phosphatase Is the Last Step of the Pathway

2007 ◽  
Vol 189 (6) ◽  
pp. 2210-2218 ◽  
Author(s):  
Carmen L. Zayas ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Salmonella Enterica ◽  
De Novo ◽  
Growth Conditions ◽  
Phosphoryl Group ◽  
Coenzyme B12 ◽  
Assembly Pathway ◽  
Serovar Typhimurium ◽  
Cobyric Acid

ABSTRACT We report that cobC strains of Salmonella enterica serovar Typhimurium are impaired in the ability to salvage cobyric acid (Cby), a de novo corrin ring biosynthetic intermediate, under aerobic growth conditions. In vivo and in vitro evidence support the conclusion that this new phenotype of cobC strains is due to the inability of serovar Typhimurium to dephosphorylate adenosylcobalamin-5′-phosphate (AdoCbl-5′-P), the product of the condensation of α-ribazole-5′-phosphate (α-RP) and adenosylcobinamide-GDP by the AdoCbl-5′-P synthase (CobS, EC 2.7.8.26) enzyme. Increased flux through the 5,6-dimethylbenzimidazole and cobinamide (Cbi) activation branches of the nucleotide loop assembly pathway in cobC strains restored AdoCbl-5′-P synthesis from Cby in a cobC strain. The rate of the CobS-catalyzed reaction was at least 2 orders of magnitude higher with α-RP than with α-ribazole as substrate. On the basis of the data reported herein, we conclude that removal of the phosphoryl group from AdoCbl-5′-P is the last step in AdoCbl biosynthesis in serovar Typhimurium and that the reaction is catalyzed by the AdoCbl-5′-P phosphatase (CobC) enzyme. Explanations for the correction of the Cby salvaging phenotype are discussed.

scholarly journals Cathelicidin Antimicrobial Peptide Expression Is Not Induced or Required for Bacterial Clearance during Salmonella enterica Infection of Human Monocyte-Derived Macrophages

2012 ◽  
Vol 80 (11) ◽  
pp. 3930-3938 ◽  
Author(s):  
Kristi L. Strandberg ◽  
Susan M. Richards ◽  
John S. Gunn
Keyword(s):  
Antimicrobial Peptide ◽  
Salmonella Enterica ◽  
Active Form ◽  
Human Monocyte ◽  
Content Type ◽  
Mutant Strains ◽  
Serovar Typhimurium ◽  
Proinflammatory Responses

ABSTRACTSalmonella entericaserovar Typhimurium is able to resist antimicrobial peptide killing by induction of the PhoP-PhoQ and PmrA-PmrB two-component systems and the lipopolysaccharide (LPS) modifications they mediate. Murine cathelin-related antimicrobial peptide (CRAMP) has been reported to inhibitS. Typhimurium growthin vitroandin vivo. We hypothesize that infection of human monocyte-derived macrophages (MDMs) withSalmonella entericaserovar Typhi andS. Typhimurium will induce human cathelicidin antimicrobial peptide (CAMP) production, and exposure to LL-37 (processed, active form of CAMP/hCAP18) will lead to upregulation of PmrAB-mediated LPS modifications and increased survivalin vivo. Unlike in mouse macrophages, in which CRAMP is upregulated during infection,campgene expression was not induced in human MDMs infected withS. Typhi orS. Typhimurium. Upon infection, intracellular levels of ΔphoPQ, ΔpmrAB, and PhoPcS. Typhi decreased over time but were not further inhibited by the vitamin D3-induced increase incampexpression. MDMs infected with wild-type (WT)S. Typhi orS. Typhimurium released similar levels of proinflammatory cytokines; however, the LPS modification mutant strains dramatically differed in MDM-elicited cytokine levels. Overall, these findings indicate thatcampis not induced duringSalmonellainfection of MDMs nor is key toSalmonellaintracellular clearance. However, the cytokine responses from MDMs infected with WT or LPS modification mutant strains differ significantly, indicating a role for LPS modifications in altering the host inflammatory response. Our findings also suggest thatS. Typhi andS. Typhimurium elicit different proinflammatory responses from MDMs, despite being capable of adding similar modifications to their LPS structures.

scholarly journals Reduced Transaminase B (IlvE) Activity Caused by the Lack of yjgF Is Dependent on the Status of Threonine Deaminase (IlvA) in Salmonella enterica Serovar Typhimurium

2004 ◽  
Vol 186 (3) ◽  
pp. 803-810 ◽  
Author(s):  
George Schmitz ◽  
Diana M. Downs
Keyword(s):  
Salmonella Enterica ◽  
Specific Activity ◽  
Acetolactate Synthase ◽  
Threonine Deaminase ◽  
Isoleucine Biosynthesis ◽  
Serovar Typhimurium ◽  
The Status ◽  
Domains Of Life

ABSTRACT The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection between yjgF and isoleucine biosynthesis in Salmonella enterica. In strains lacking yjgF the specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence of yjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lacking yjgF showed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools.

scholarly journals Terminal Deoxynucleotidyl Transferase Is Not Required for Antibody Response to Polysaccharide Vaccines againstStreptococcus pneumoniaeandSalmonella entericaSerovar Typhi

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Vivek Belde ◽  
Matthew P. Cravens ◽  
Dania Gulandijany ◽  
Justin A. Walker ◽  
Isabel Palomo-Caturla ◽  
...  
Keyword(s):  
Antibody Response ◽  
B Cell ◽  
Salmonella Enterica ◽  
Passive Immunization ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Human Infants ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTB cell antigen receptor (BCR) diversity increases by several orders of magnitude due to the action of terminal deoxynucleotidyl transferase (TdT) during V(D)J recombination. Unlike adults, infants have limited BCR diversity, in part due to reduced expression of TdT. Since human infants and young mice respond poorly to polysaccharide vaccines, such as the pneumococcal polysaccharide vaccine Pneumovax23 and Vi polysaccharide (ViPS) ofSalmonella entericaserovar Typhi, we tested the contribution of TdT-mediated BCR diversity in response to these vaccines. We found that TdT+/−and TdT−/−mice generated comparable antibody responses to Pneumovax23 and survivedStreptococcus pneumoniaechallenge. Moreover, passive immunization of B cell-deficient mice with serum from Pneumovax23-immunized TdT+/−or TdT−/−mice conferred protection. TdT+/−and TdT−/−mice generated comparable levels of anti-ViPS antibodies and antibody-dependent, complement-mediated bactericidal activity againstS. Typhiin vitro. To test the protective immunity conferred by ViPS immunizationin vivo, TdT+/−and TdT−/−mice were challenged with a chimericSalmonella entericaserovar Typhimurium strain expressing ViPS, since mice are nonpermissive hosts forS. Typhi infection. Compared to their unimmunized counterparts, immunized TdT+/−and TdT−/−mice challenged with ViPS-expressingS. Typhimurium exhibited a significant reduction in the bacterial burden and liver pathology. These data suggest that the impaired antibody response to the Pneumovax23 and ViPS vaccines in the young is not due to limited TdT-mediated BCR diversification.

scholarly journals Attenuation of Salmonella enterica Serovar Typhimurium by Altering Biological Functions of Murein Lipoprotein and Lipopolysaccharide

2005 ◽  
Vol 73 (12) ◽  
pp. 8433-8436 ◽  
Author(s):  
A. A. Fadl ◽  
J. Sha ◽  
G. R. Klimpel ◽  
J. P. Olano ◽  
C. L. Galindo ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Biological Functions ◽  
Double Knockout ◽  
In Vivo Models ◽  
Background Strain ◽  
Knockout Mutants ◽  
Serovar Typhimurium

ABSTRACT We constructed Salmonella enterica serovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from an msbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models of Salmonella pathogenesis.

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