Characterization of the haem oxygenase protein family in Arabidopsis thaliana reveals a diversity of functions

2009 ◽  
Vol 425 (2) ◽  
pp. 425-434 ◽  
Author(s):  
Bjoern Gisk ◽  
Yukiko Yasui ◽  
Takayuki Kohchi ◽  
Nicole Frankenberg-Dinkel
Keyword(s):  
Arabidopsis Thaliana ◽  
Electron Donor ◽  
Fluorescent Protein ◽  
Chlorophyll Biosynthesis ◽  
Protoporphyrin Ix ◽  
Fold Increase ◽  
Transit Peptides ◽  
Tetrapyrrole Metabolism ◽  
Haem Oxygenase ◽  
Green Fluorescent

HOs (haem oxygenases) catalyse the oxidative cleavage of haem to BV (biliverdin), iron and carbon monoxide. In plants, the product of the reaction is BV IXα, the precursor of the PHY (phytochrome) chromophore and is thus essential for proper photomorphogenesis. Arabidopsis thaliana contains one major biochemically characterized HO (HY1) and three additional putative HOs (HO2, HO3 and HO4). All four proteins are encoded in the nucleus but contain chloroplast translocation sequences at their N-termini. The transit peptides of all four proteins are sufficient for chloroplast translocalization as shown by GFP (green fluorescent protein) reporter gene fusions. Overall, all four proteins can be divided into two subfamilies: HO1 and HO2. Here we show that all members of the HO1 subfamily (HY1, HO3 and HO4) are active monomeric HOs and can convert haem to BV IXα using spinach Fd (ferredoxin) as an electron donor. Addition of a second electron donor, such as ascorbate, led to a 10-fold increase in the haem conversion rate. Furthermore, haem turnover is also promoted by light when spinach thylakoids are present. All HO1 family members displayed similar kinetic parameters indicating they all have a possible involvement in PHY chromophore biosynthesis. HO2 did not yield sufficient amounts of soluble protein and therefore required the construction of a synthetic gene adapted to the codon usage of Escherichia coli. HO2 is unable to bind or degrade haem and therefore it is not a haem oxygenase. However, HO2 shows strong binding of proto IX (protoporphyrin IX), a precursor for both haem and chlorophyll biosynthesis. A possible function of HO2 in the regulation of tetrapyrrole metabolism is discussed.

scholarly journals Colonization of Arabidopsis thaliana with Salmonella enterica and Enterohemorrhagic Escherichia coli O157:H7 and Competition by Enterobacter asburiae

2003 ◽  
Vol 69 (8) ◽  
pp. 4915-4926 ◽  
Author(s):  
Michael B. Cooley ◽  
William G. Miller ◽  
Robert E. Mandrell
Keyword(s):  
Escherichia Coli ◽  
Arabidopsis Thaliana ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Enterohemorrhagic Escherichia Coli ◽  
Plant Responses ◽  
Human Pathogens ◽  
E Coli ◽  
Green Fluorescent ◽  
Enterobacter Asburiae

ABSTRACT Enteric pathogens, such as Salmonella enterica and Escherichia coli O157:H7, have been shown to contaminate fresh produce. Under appropriate conditions, these bacteria will grow on and invade the plant tissue. We have developed Arabidopsis thaliana (thale cress) as a model system with the intention of studying plant responses to human pathogens. Under sterile conditions and at 100% humidity, S. enterica serovar Newport and E. coli O157:H7 grew to 109 CFU g−1 on A. thaliana roots and to 2 × 107 CFU g−1 on shoots. Furthermore, root inoculation led to contamination of the entire plant, indicating that the pathogens are capable of moving on or within the plant in the absence of competition. Inoculation with green fluorescent protein-labeled S. enterica and E. coli O157:H7 showed invasion of the roots at lateral root junctions. Movement was eliminated and invasion decreased when nonmotile mutants of S. enterica were used. Survival of S. enterica serovar Newport and E. coli O157:H7 on soil-grown plants declined as the plants matured, but both pathogens were detectable for at least 21 days. Survival of the pathogen was reduced in unautoclaved soil and amended soil, suggesting competition from indigenous epiphytes from the soil. Enterobacter asburiae was isolated from soil-grown A. thaliana and shown to be effective at suppressing epiphytic growth of both pathogens under gnotobiotic conditions. Seed and chaff harvested from contaminated plants were occasionally contaminated. The rate of recovery of S. enterica and E. coli O157:H7 from seed varied from undetectable to 19% of the seed pools tested, depending on the method of inoculation. Seed contamination by these pathogens was undetectable in the presence of the competitor, Enterobacter asburiae. Sampling of 74 pools of chaff indicated a strong correlation between contamination of the chaff and seed (P = 0.025). This suggested that contamination of the seed occurred directly from contaminated chaff or by invasion of the flower or silique. However, contaminated seeds were not sanitized by extensive washing and chlorine treatment, indicating that some of the bacteria reside in a protected niche on the seed surface or under the seed coat.

scholarly journals Interdependence of the Peroxisome-targeting Receptors in Arabidopsis thaliana: PEX7 Facilitates PEX5 Accumulation and Import of PTS1 Cargo into Peroxisomes

2010 ◽  
Vol 21 (7) ◽  
pp. 1263-1271 ◽  
Author(s):  
Naxhiely Martínez Ramón ◽  
Bonnie Bartel
Keyword(s):  
Arabidopsis Thaliana ◽  
Green Fluorescent Protein ◽  
Protein Import ◽  
Fluorescent Protein ◽  
Protein Accumulation ◽  
Animal Development ◽  
Metabolic Reactions ◽  
Targeting Signals ◽  
Green Fluorescent ◽  
Peroxisome Targeting Signals

Peroxisomes compartmentalize certain metabolic reactions critical to plant and animal development. The import of proteins from the cytosol into the organelle matrix depends on more than a dozen peroxin (PEX) proteins, with PEX5 and PEX7 serving as receptors that shuttle proteins bearing one of two peroxisome-targeting signals (PTSs) into the organelle. PEX5 is the PTS1 receptor; PEX7 is the PTS2 receptor. In plants and mammals, PEX7 depends on PEX5 binding to deliver PTS2 cargo into the peroxisome. In this study, we characterized a pex7 missense mutation, pex7-2, that disrupts both PEX7 cargo binding and PEX7-PEX5 interactions in yeast, as well as PEX7 protein accumulation in plants. We examined localization of peroxisomally targeted green fluorescent protein derivatives in light-grown pex7 mutants and observed not only the expected defects in PTS2 protein import but also defects in PTS1 import. These PTS1 import defects were accompanied by reduced PEX5 accumulation in light-grown pex7 seedlings. Our data suggest that PEX5 and PTS1 import depend on the PTS2 receptor PEX7 in Arabidopsis and that the environment may influence this dependence. These data advance our understanding of the biogenesis of these essential organelles and provide a possible rationale for the retention of the PTS2 pathway in some organisms.

scholarly journals Alternative transcription and feedback regulation suggest that SlIDI1 is involved in tomato carotenoid synthesis in a complex way.

2022 ◽  
Vol 9 ◽  
Author(s):  
Ming Zhou ◽  
Lei Deng ◽  
Shaogui Guo ◽  
Guoliang Yuan ◽  
Chuanyou Li ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Fluorescent Protein ◽  
Recessive Gene ◽  
Feedback Regulation ◽  
Pcr Analysis ◽  
Protein Fusion ◽  
Transit Peptides ◽  
Alternative Transcription ◽  
Green Fluorescent ◽  
Β Carotene

Abstract Carotenoid pigments confer photoprotection and visual attraction and serve as precursors for many important signaling molecules. Herein, the orange-fruited phenotype of a tomato elite inbred line resulting from sharply reduced carotenoid levels and an increased β-carotene-to-lycopene ratio in fruit was shown to be controlled by a single recessive gene, oft3. BSA-Seq combined with fine mapping delimited the oft3 gene to a 71.23 kb interval on chromosome 4, including eight genes. Finally, the oft3 candidate gene SlIDI1, harboring a 116 bp deletion mutation, was identified by genome sequence analysis. Further functional complementation and CRISPR–Cas9 knockout experiments confirmed that SlIDI1 was the gene underlying the oft3 locus. qRT–PCR analysis revealed that the expression of SlIDI1 was highest in flowers and fruit and increased with fruit ripening or flower maturation. SlIDI1 simultaneously produced long and short transcripts by alternative transcription initiation and alternative splicing. Green fluorescent protein fusion expression revealed that the long isoform was mainly localized in plastids and that an N-terminal 59-amino acid extension sequence was responsible for plastid targeting. Short transcripts were identified in leaves and fruit by 5’ RACE and in fruit by 3’ RACE, which produced corresponding proteins lacking transit peptides and/or putative peroxisome targeting sequences, respectively. In SlIDI1 mutant fruit, SlBCH1 transcription involved in β-carotenoid catabolism was obviously suppressed, which may be responsible for the higher β-carotene-to-lycopene ratio and suggested potential feedback regulatory mechanisms involved in carotenoid pathway flux.

A plastidial pantoate transporter with a potential role in pantothenate synthesis

2018 ◽  
Vol 475 (4) ◽  
pp. 813-825 ◽  
Author(s):  
Lili Huang ◽  
Michal Pyc ◽  
Saleh Alseekh ◽  
Donald R. McCarty ◽  
Valérie de Crécy-Lagard ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Potential Role ◽  
Fluorescent Protein ◽  
Comparative Genomic ◽  
Reduction Step ◽  
Knockout Mutants ◽  
Vitamin B5 ◽  
Green Fluorescent ◽  
Inner Envelope ◽  
Pantothenate Biosynthesis

The pantothenate (vitamin B5) synthesis pathway in plants is not fully defined because the subcellular site of its ketopantoate → pantoate reduction step is unclear. However, the pathway is known to be split between cytosol, mitochondria, and potentially plastids, and inferred to involve mitochondrial or plastidial transport of ketopantoate or pantoate. No proteins that mediate these transport steps have been identified. Comparative genomic and transcriptomic analyses identified Arabidopsis thaliana BASS1 (At1g78560) and its maize (Zea mays) ortholog as candidates for such a transport role. BASS1 proteins belong to the bile acid : sodium symporter family and share similarity with the Salmonella enterica PanS pantoate/ketopantoate transporter and with predicted bacterial transporters whose genes cluster on the chromosome with pantothenate synthesis genes. Furthermore, Arabidopsis BASS1 is co-expressed with genes related to metabolism of coenzyme A, the cofactor derived from pantothenate. Expression of Arabidopsis or maize BASS1 promoted the growth of a S. enterica panB panS mutant strain when pantoate, but not ketopantoate, was supplied, and increased the rate of [3H]pantoate uptake. Subcellular localization of green fluorescent protein fusions in Nicotiana tabacum BY-2 cells demonstrated that Arabidopsis BASS1 is targeted solely to the plastid inner envelope. Two independent Arabidopsis BASS1 knockout mutants accumulated pantoate ∼10-fold in leaves and had smaller seeds. Taken together, these data indicate that BASS1 is a physiologically significant plastidial pantoate transporter and that the pantoate reduction step in pantothenate biosynthesis could be at least partly localized in plastids.

scholarly journals Ypr140wp, ‘the yeast tafazzin’, displays a mitochondrial lysophosphatidylcholine (lyso-PC) acyltransferase activity related to triacylglycerol and mitochondrial lipid synthesis

2005 ◽  
Vol 387 (3) ◽  
pp. 617-626 ◽  
Author(s):  
Eric TESTET ◽  
Jeanny LAROCHE-TRAINEAU ◽  
Abdelmajid NOUBHANI ◽  
Denis COULON ◽  
Odile BUNOUST ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Lipid Synthesis ◽  
Fold Increase ◽  
Mitochondrial Fraction ◽  
Yeast Cells ◽  
Wild Type ◽  
Acyltransferase Activity ◽  
Microscopy Analysis ◽  
Mitochondrial Lipid ◽  
Green Fluorescent

When the yeast protein Ypr140w was expressed in Escherichia coli, a lyso-PC [lysophosphatidylcholine (1-acylglycerophosphorylcholine)] acyltransferase activity was found associated with the membranes of the bacteria. To our knowledge, this is the first identification of a protein capable of catalysing the acylation of lyso-PC molecules to form PC. Fluorescence microscopy analysis of living yeasts revealed that the fusion protein Ypr140w–green fluorescent protein is targeted to the mitochondria. Moreover, in contrast with wild-type cells, in the absence of acyl-CoA, the yeast mutant deleted for the YPR140w gene has no lyso-PC acyltransferase activity associated with the mitochondrial fraction. When yeast cells were grown in the presence of lactate, the mutant synthesized 2-fold more triacylglycerols when compared with the wild-type. Moreover, its mitochondrial membranes contained a lesser amount of PC and cardiolipin, and the fatty acid composition of these latter was greatly changed. These modifications were accompanied by a 2-fold increase in the respiration rates (states 3 and 4) of the mitochondria. The relationship between the deletion of the YPR140w gene and the lipid composition of the ypr140wΔ cells is discussed.

scholarly journals Cloning and Expression Analysis of the BocMBF1c Gene Involved in Heat Tolerance in Chinese Kale

2019 ◽  
Vol 20 (22) ◽  
pp. 5637 ◽  
Author(s):  
Lifang Zou ◽  
Bingwei Yu ◽  
Xing-Liang Ma ◽  
Bihao Cao ◽  
Guoju Chen ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Heat Stress ◽  
Green Fluorescent Protein ◽  
Stress Response ◽  
Nicotiana Benthamiana ◽  
Thermal Tolerance ◽  
Fluorescent Protein ◽  
Leaf Tissue ◽  
Chinese Kale ◽  
Green Fluorescent

Chinese kale (Brassica oleracea var. chinensis Lei) is an important vegetable crop in South China, valued for its nutritional content and taste. Nonetheless, the thermal tolerance of Chinese kale still needs improvement. Molecular characterization of Chinese kale’s heat stress response could provide a timely solution for developing a thermally tolerant Chinese kale variety. Here, we report the cloning of multi-protein bridging factor (MBF) 1c from Chinese kale (BocMBF1c), an ortholog to the key heat stress responsive gene MBF1c. Phylogenetic analysis showed that BocMBF1c is highly similar to the stress-response transcriptional coactivator MBF1c from Arabidopsis thaliana (AtMBF1c), and the BocMBF1c coding region conserves MBF1 and helix-turn-helix (HTH) domains. Moreover, the promoter region of BocMBF1c contains three heat shock elements (HSEs) and, thus, is highly responsive to heat treatment. This was verified in Nicotiana benthamiana leaf tissue using a green fluorescent protein (GFP) reporter. In addition, the expression of BocMBF1c can be induced by various abiotic stresses in Chinese kale which indicates the involvement of stress responses. The BocMBF1c-eGFP (enhanced green fluorescent protein) chimeric protein quickly translocated into the nucleus under high temperature treatment in Nicotiana benthamiana leaf tissue. Overexpression of BocMBF1c in Arabidopsis thaliana results in a larger size and enhanced thermal tolerance compared with the wild type. Our results provide valuable insight for the role of BocMBF1c during heat stress in Chinese kale.

scholarly journals An epifluorescent attachment improves whole-plant digital photography of Arabidopsis thaliana expressing red-shifted green fluorescent protein

AoB Plants ◽  
2012 ◽  
Vol 2012 ◽  
Author(s):  
Stokes S. Baker ◽  
Cleo B. Vidican ◽  
David S. Cameron ◽  
Haittam G. Greib ◽  
Christine C. Jarocki ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Digital Photography ◽  
Whole Plant ◽  
Green Fluorescent
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