Hemerythrins enhance aerobic respiration in Methylomicrobium alcaliphilum 20ZR, a methane-consuming bacterium

2020 ◽  
Vol 367 (2) ◽  
Author(s):  
Snehal Nariya ◽  
Marina G Kalyuzhnaya
Keyword(s):  
Methane Oxidation ◽  
Metal Binding ◽  
Carbon Conversion ◽  
Wild Type ◽  
Cellular Functions ◽  
Iron Proteins ◽  
Methane Consumption ◽  
Core Enzyme ◽  
Consumption Rates ◽  
Methylomicrobium Alcaliphilum

ABSTRACT Numerous hemerythrins, di-iron proteins, have been identified in prokaryote genomes, but in most cases their function remains elusive. Bacterial hemerythrin homologs (bacteriohemerythrins, Bhrs) may contribute to various cellular functions, including oxygen sensing, metal binding and antibiotic resistance. It has been proposed that methanotrophic Bhrs support methane oxidation by supplying oxygen to a core enzyme, particulate methane monooxygenase. In this study, the consequences of the overexpression or deletion of the Bhr gene (bhr) in Methylomicrobiam alcaliphillum 20ZR were investigated. We found that the bhrknockout (20ZRΔbhr) displays growth kinetics and methane consumption rates similar to wild type. However, the 20ZRΔbhr accumulates elevated concentrations of acetate at aerobic conditions, indicating slowed respiration. The methanotrophic strain overproducing Bhr shows increased oxygen consumption and reduced carbon-conversion efficiency, while its methane consumption rates remain unchanged. These results suggest that the methanotrophic Bhr proteins specifically contribute to oxygen-dependent respiration, while they have minimal, if any, input of oxygen for the methane oxidation machinery.

scholarly journals An improved assay for bacterial methane mono-oxygenase: some properties of the enzyme from Methylomonas methanica

1975 ◽  
Vol 151 (2) ◽  
pp. 459-462 ◽  
Author(s):  
J Colby ◽  
H Dalton ◽  
R Whittenbury
Keyword(s):  
Metal Ions ◽  
Methane Oxidation ◽  
Metal Binding ◽  
Methylomonas Methanica

Extracts of Methylomonas methanica catalyse the O2-and NAD(P)H-dependent disappearance of bromomethane. The activity is unstable at 2 degrees C but is stable at --70 degrees C for several weeks. Bromomethane mono-oxygenase is particulate and is inhibited by metal-binding reagents, by compounds SKF 525A and Lilly 53325, by some metal ions and by acetylene. Evidence is presented that indicates that bromomethane mono-oxygenase is the enzyme responsible for methane oxidation in vivo.

scholarly journals PF16 encodes a protein with armadillo repeats and localizes to a single microtubule of the central apparatus in Chlamydomonas flagella.

1996 ◽  
Vol 132 (3) ◽  
pp. 359-370 ◽  
Author(s):  
E F Smith ◽  
P A Lefebvre
Keyword(s):  
Protein Interactions ◽  
Insertional Mutagenesis ◽  
Flagellar Motility ◽  
Wild Type ◽  
Protein Protein Interactions ◽  
Cellular Functions ◽  
Central Pair ◽  
Central Apparatus ◽  
Immunofluorescence Labeling ◽  
Armadillo Repeats

Several studies have indicated that the central pair of microtubules and their associated structures play a significant role in regulating flagellar motility. To begin a molecular analysis of these components we have generated central apparatus-defective mutants in Chlamydomonas reinhardtii using insertional mutagenesis. One paralyzed mutant recovered in our screen, D2, is an allele of a previously identified mutant, pf16. Mutant cells have paralyzed flagella, and the C1 microtubule of the central apparatus is missing in isolated axonemes. We have cloned the wild-type PF16 gene and confirmed its identity by rescuing pf16 mutants upon transformation. The rescued pf16 cells were wild-type in motility and in axonemal ultrastructure. A full-length cDNA clone for PF16 was obtained and sequenced. Database searches using the predicted 566 amino acid sequence of PF16 indicate that the protein contains eight contiguous armadillo repeats. A number of proteins with diverse cellular functions also contain armadillo repeats including pendulin, Rch1, importin, SRP-1, and armadillo. An antibody was raised against a fusion protein expressed from the cloned cDNA. Immunofluorescence labeling of wild-type flagella indicates that the PF16 protein is localized along the length of the flagella while immunogold labeling further localizes the PF16 protein to a single microtubule of the central pair. Based on the localization results and the presence of the armadillo repeats in this protein, we suggest that the PF16 gene product is involved in protein-protein interactions important for C1 central microtubule stability and flagellar motility.

scholarly journals Increased metal tolerance and bioaccumulation of zinc and cadmium in Chlamydomonas reinhardtii expressing a AtHMA4 C-terminal domain protein

2020 ◽  
Author(s):  
Aniefon Ibuot ◽  
Rachel E. Webster ◽  
Lorraine E. Williams ◽  
Jon K. Pittman
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Metal Binding ◽  
Metal Tolerance ◽  
Alginate Beads ◽  
Full Length ◽  
Wild Type ◽  
Microalgal Biomass ◽  
Terminal Domain ◽  
Metal Biosorption ◽  
Transgenic Cells

AbstractThe use of microalgal biomass for metal pollutant bioremediation might be improved by genetic engineering to modify the selectivity or capacity of metal biosorption. A plant cadmium (Cd) and zinc (Zn) transporter (AtHMA4) was used as a transgene to increase the ability of Chlamydomonas reinhardtii to tolerate 0.2 mM Cd and 0.3 mM Zn exposure. The transgenic cells showed increased accumulation and internalisation of both metals compared to wild type. AtHMA4 was expressed either as the full-length protein or just the C-terminal tail, which is known to have metal binding sites. Similar Cd and Zn tolerance and accumulation was observed with expression of either the full-length protein or C-terminal domain, suggesting that enhanced metal tolerance was mainly due to increased metal binding rather than metal transport. The effectiveness of the transgenic cells was further examined by immobilisation in calcium alginate to generate microalgal beads that could be added to a metal contaminated solution. Immobilisation maintained metal tolerance, while AtHMA4-expressing cells in alginate showed a concentration-dependent increase in metal biosorption that was significantly greater than alginate beads composed of wild type cells. This demonstrates that expressing AtHMA4 full-length or C-terminus has great potential as a strategy for bioremediation using microalgal biomass.

Impaired mechanical stability, migration and contractile capacity in vimentin-deficient fibroblasts

1998 ◽  
Vol 111 (13) ◽  
pp. 1897-1907 ◽  
Author(s):  
B. Eckes ◽  
D. Dogic ◽  
E. Colucci-Guyon ◽  
N. Wang ◽  
A. Maniotis ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Mechanical Stability ◽  
Wild Type Mouse ◽  
Wild Type ◽  
Cellular Functions ◽  
Primary Fibroblasts ◽  
In Vitro Systems ◽  
Filament Network ◽  
Collagen Lattices

Loss of a vimentin network due to gene disruption created viable mice that did not differ overtly from wild-type littermates. Here, primary fibroblasts derived from vimentin-deficient (-/-) and wild-type (+/+) mouse embryos were cultured, and biological functions were studied in in vitro systems resembling stress situations. Stiffness of -/- fibroblasts was reduced by 40% in comparison to wild-type cells. Vimentin-deficient cells also displayed reduced mechanical stability, motility and directional migration towards different chemo-attractive stimuli. Reorganization of collagen fibrils and contraction of collagen lattices were severely impaired. The spatial organization of focal contact proteins, as well as actin microfilament organization was disturbed. Thus, absence of a vimentin filament network does not impair basic cellular functions needed for growth in culture, but cells are mechanically less stable, and we propose that therefore they are impaired in all functions depending upon mechanical stability.

scholarly journals Function of a Chemotaxis-Like Signal Transduction Pathway in Modulating Motility, Cell Clumping, and Cell Length in the Alphaproteobacterium Azospirillum brasilense

2008 ◽  
Vol 190 (19) ◽  
pp. 6365-6375 ◽  
Author(s):  
Amber N. Bible ◽  
Bonnie B. Stephens ◽  
Davi R. Ortega ◽  
Zhihong Xie ◽  
Gladys Alexandre
Keyword(s):  
Signal Transduction ◽  
Signal Transduction Pathway ◽  
Cell Aggregation ◽  
Cell Length ◽  
Transduction Pathway ◽  
Wild Type ◽  
Cellular Functions ◽  
Swimming Pattern ◽  
A Minor ◽  
Nutritional Imbalance

ABSTRACT A chemotaxis signal transduction pathway (hereafter called Che1) has been previously identified in the alphaproteobacterium Azospirillum brasilense. Previous experiments have demonstrated that although mutants lacking CheB and/or CheR homologs from this pathway are defective in chemotaxis, a mutant in which the entire chemotaxis pathway has been mutated displayed a chemotaxis phenotype mostly similar to that of the parent strain, suggesting that the primary function of this Che1 pathway is not the control of motility behavior. Here, we report that mutants carrying defined mutations in the cheA1 (strain AB101) and the cheY1 (strain AB102) genes and a newly constructed mutant lacking the entire operon [Δ(cheA1-cheR1)::Cm] (strain AB103) were defective, but not null, for chemotaxis and aerotaxis and had a minor defect in swimming pattern. We found that mutations in genes of the Che1 pathway affected the cell length of actively growing cells but not their growth rate. Cells of a mutant lacking functional cheB1 and cheR1 genes (strain BS104) were significantly longer than wild-type cells, whereas cells of mutants impaired in the cheA1 or cheY1 genes, as well as a mutant lacking a functional Che1 pathway, were significantly shorter than wild-type cells. Both the modest chemotaxis defects and the observed differences in cell length could be complemented by expressing the wild-type genes from a plasmid. In addition, under conditions of high aeration, cells of mutants lacking functional cheA1 or cheY1 genes or the Che1 operon formed clumps due to cell-to-cell aggregation, whereas the mutant lacking functional CheB1 and CheR1 (BS104) clumped poorly, if at all. Further analysis suggested that the nature of the exopolysaccharide produced, rather than the amount, may be involved in this behavior. Interestingly, mutants that displayed clumping behavior (lacking cheA1 or cheY1 genes or the Che1 operon) also flocculated earlier and quantitatively more than the wild-type cells, whereas the mutant lacking both CheB1 and CheR1 was delayed in flocculation. We propose that the Che1 chemotaxis-like pathway modulates the cell length as well as clumping behavior, suggesting a link between these two processes. Our data are consistent with a model in which the function of the Che1 pathway in regulating these cellular functions directly affects flocculation, a cellular differentiation process initiated under conditions of nutritional imbalance.

Metallothionein is a crucial protective factor againstHelicobacter pylori-induced gastric erosive lesions in a mouse model

2008 ◽  
Vol 294 (4) ◽  
pp. G877-G884 ◽  
Author(s):  
Masaharu Mita ◽  
Masahiko Satoh ◽  
Akinori Shimada ◽  
Mina Okajima ◽  
Sadahiro Azuma ◽  
...  
Keyword(s):  
Metal Binding ◽  
Protective Factor ◽  
Histopathological Examination ◽  
Inflammatory Cells ◽  
Gastric Injury ◽  
Wild Type ◽  
Inflammatory Protein ◽  
Ros Scavenger ◽  
H Pylori

Infection with the gastric pathogen Helicobacter pylori ( H. pylori) causes chronic gastritis, peptic ulcer, and gastric adenocarcinoma. These diseases are associated with production of reactive oxygen species (ROS) from infiltrated macrophages and neutrophiles in inflammatory sites. Metallothionein (MT) is a low-molecular-weight, cysteine-rich protein that can act not only as a metal-binding protein, but also as a ROS scavenger. In the present study, we examined the role of MT in the protection against H. pylori-induced gastric injury using MT-null mice. Female MT-null and wild-type mice were challenged with H. pylori SS1 strain, and then histological changes were evaluated with the updated Sydney grading system at 17 and 21 wk after challenge. Although the colonization efficiency of H. pylori was essentially the same for MT-null and wild-type mice, the scores of activity of inflammatory cells were significantly higher in MT-null mice than in wild-type mice at 17 wk after challenge. Histopathological examination revealed erosive lesions accompanied by infiltration of inflammatory cells in the infected MT-null mice but not in wild-type mice. Furthermore, activation of NF-κB and expression of NF-κB-mediated chemokines such as macrophage inflammatory protein-1α and monocytes chemoattractant protein-1 in gastric cells were markedly higher in MT-null mice than in wild-type mice. These results suggest that MT in the gastric mucosa might play an important role in the protection against H. pylori-induced gastric ulceration.

scholarly journals The Regulator PerR Is Involved in Oxidative Stress Response and Iron Homeostasis and Is Necessary for Full Virulence of Streptococcus pyogenes

2002 ◽  
Vol 70 (9) ◽  
pp. 4968-4976 ◽  
Author(s):  
Susanna Ricci ◽  
Robert Janulczyk ◽  
Lars Björck
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Pyogenes ◽  
Stress Responses ◽  
Metal Binding ◽  
Iron Homeostasis ◽  
Bacterial Species ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Allelic Replacement

ABSTRACT Ferric uptake regulator (Fur) and Fur-like proteins form an important family of transcriptional regulators in many bacterial species. In this work we have characterized a Fur-like protein, the peroxide regulator PerR, in an M1 serotype of Streptococcus pyogenes. To determine the role of PerR in S. pyogenes, we inactivated the gene by allelic replacement. PerR-deficient bacteria showed 48% reduction of 55Fe incorporation from the culture medium. Transcriptional analysis revealed that mtsA, encoding a metal-binding protein of an ABC transporter in S. pyogenes, was transcribed at lower levels than were wild-type cells. Although total iron accumulation was reduced, the growth of the mutant strain was not significantly hampered. The mutant showed hyperresistance to hydrogen peroxide, and this response was induced in wild-type cells by growth in aerobiosis, suggesting that PerR acts as an oxidative stress-responsive repressor. PerR may also participate in the response to superoxide stress, as the perR mutant was more sensitive to the superoxide anion and had a reduced transcription of sodA, which encodes the sole superoxide dismutase of S. pyogenes. Complementation of the mutation with a functional perR gene restored 55Fe incorporation, response to peroxide stress, and transcription of both mtsA and sodA to levels comparable to those of wild-type bacteria. Finally, the perR mutant was attenuated in virulence in a murine air sac model of infection (P < 0.05). These results demonstrate that PerR is involved in the regulation of iron homeostasis and oxidative stress responses and that it contributes to the virulence of S. pyogenes.

Sign in / Sign up

Export Citation Format

Share Document