scholarly journals Involvement of THH1, an Arabidopsis thaliana homologue of the TOM1 gene, in tobamovirus multiplication

2006 ◽  
Vol 87 (8) ◽  
pp. 2397-2401 ◽  
Author(s):  
Koki Fujisaki ◽  
Gerald B. Ravelo ◽  
Satoshi Naito ◽  
Masayuki Ishikawa
Keyword(s):  
Arabidopsis Thaliana ◽  
Coat Protein ◽  
Double Mutant ◽  
Detectable Level ◽  
Expression Level ◽  
Wild Type ◽  
Homologous Proteins ◽  
Single Mutant ◽  
Mutant Lines

The TOM1 and TOM3 genes of Arabidopsis thaliana encode homologous proteins that are required for tobamovirus multiplication. Although the A. thaliana genome encodes another TOM1-like gene, THH1, the tobamovirus coat protein (CP) does not accumulate to a detectable level in the tom1 tom3 double mutant. Here, double and triple mutants of tom1, tom3 and thh1 were generated to investigate whether THH1 functions to support tobamovirus multiplication. In the tom1 thh1 double mutant, the tobamovirus CP accumulated to a level that was detectable, but lower than that in the tom1 single mutant. In tom1 tom3 double-mutant lines overexpressing THH1, the tobamovirus CP accumulated to a level similar to that observed in wild-type plants. These results suggest that THH1 supports tobamovirus multiplication, but to a lesser extent than TOM1 and TOM3. The expression level of THH1 is lower than that of TOM1 and TOM3, which might explain the smaller contribution of THH1 to tobamovirus multiplication.

scholarly journals Alpha Carbonic Anhydrase 5 Mediates Stimulation of ATP Synthesis by Bicarbonate in Isolated Arabidopsis Thylakoids

2021 ◽  
Vol 12 ◽  
Author(s):  
Tatiana P. Fedorchuk ◽  
Inga A. Kireeva ◽  
Vera K. Opanasenko ◽  
Vasily V. Terentyev ◽  
Natalia N. Rudenko ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Arabidopsis Thaliana ◽  
Carbonic Anhydrase ◽  
Atp Synthesis ◽  
Thylakoid Membranes ◽  
Wild Type ◽  
Gene Encoding ◽  
Mutant Lines ◽  
Stimulation Of ◽  
Soluble Carbonic Anhydrase

We studied bicarbonate-induced stimulation of photophosphorylation in thylakoids isolated from leaves of Arabidopsis thaliana plants. This stimulation was not observed in thylakoids of wild-type in the presence of mafenide, a soluble carbonic anhydrase inhibitor, and was absent in thylakoids of two mutant lines lacking the gene encoding alpha carbonic anhydrase 5 (αCA5). Using mass spectrometry, we revealed the presence of αCA5 in stromal thylakoid membranes of wild-type plants. A possible mechanism of the photophosphorylation stimulation by bicarbonate that involves αCA5 is proposed.

The early-flowering mutant efs is involved in the autonomous promotion pathway of Arabidopsis thaliana

Development ◽  
1999 ◽  
Vol 126 (21) ◽  
pp. 4763-4770 ◽  
Author(s):  
W.J. Soppe ◽  
L. Bentsink ◽  
M. Koornneef
Keyword(s):  
Arabidopsis Thaliana ◽  
Flowering Time ◽  
Double Mutant ◽  
Plant Size ◽  
Early Flowering ◽  
Wild Type ◽  
Late Flowering ◽  
Long Day ◽  
Short Days ◽  
Transition To Flowering

The transition to flowering is a crucial moment in a plant's life cycle of which the mechanism has only been partly revealed. In a screen for early flowering, after mutagenesis of the late-flowering fwa mutant of Arabidopsis thaliana, the early flowering in short days (efs) mutant was identified. Under long-day light conditions, the recessive monogenic efs mutant flowers at the same time as wild type but, under short-day conditions, the mutant flowers much earlier. In addition to its early-flowering phenotype, efs has several pleiotropic effects such as a reduction in plant size, fertility and apical dominance. Double mutant analysis with several late-flowering mutants from the autonomous promotion (fca and fve) and the photoperiod promotion (co, fwa and gi) pathways of flowering showed that efs reduces the flowering time of all these mutants. However, efs is completely epistatic to fca and fve but additive to co, fwa and gi, indicating that EFS is an inhibitor of flowering specifically involved in the autonomous promotion pathway. A vernalisation treatment does not further reduce the flowering time of the efs mutant, suggesting that vernalisation promotes flowering through EFS. By comparing the length of the juvenile and adult phases of vegetative growth for wild-type, efs and the double mutant plants, it is apparent that efs mainly reduces the length of the adult phase.

The reactivation of tabun-inhibited mutant AChE with Ortho-7: steered molecular dynamics and quantum chemical studies

2016 ◽  
Vol 12 (4) ◽  
pp. 1224-1231 ◽  
Author(s):  
Rabindranath Lo ◽  
Nellore Bhanu Chandar ◽  
Shibaji Ghosh ◽  
Bishwajit Ganguly
Keyword(s):  
Molecular Dynamics ◽  
In Silico ◽  
Quantum Chemical ◽  
Double Mutant ◽  
Steered Molecular Dynamics ◽  
Wild Type ◽  
Single Mutant ◽  
Chemical Studies ◽  
Quantum Chemical Studies

Tabun inhibited AChE can be reactivated more easily with a single mutant than with a wild-type or double mutant: an in silico study.

scholarly journals Helicobacter pylori perceives the quorum-sensing molecule AI-2 as a chemorepellent via the chemoreceptor TlpB

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2445-2455 ◽  
Author(s):  
Bethany A. Rader ◽  
Christopher Wreden ◽  
Kevin G. Hicks ◽  
Emily Goers Sweeney ◽  
Karen M. Ottemann ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Double Mutant ◽  
Soft Agar ◽  
Dependent Manner ◽  
Wild Type ◽  
Environmental Chemical ◽  
Single Mutant ◽  
Autoinducer 2 ◽  
Reduced Frequency ◽  
H Pylori

Helicobacter pylori moves in response to environmental chemical cues using a chemotaxis two-component signal-transduction system. Autoinducer-2 (AI-2) is a quorum-sensing signal produced by the LuxS protein that accumulates in the bacterial environment in a density-dependent manner. We showed previously that a H. pylori luxS mutant was defective in motility on soft agar plates. Here we report that deletion of the luxS gene resulted in swimming behaviour with a reduced frequency of stops as compared to the wild-type strain. Stopping frequency was restored to wild-type levels by genetic complementation of the luxS mutation or by addition of synthetic 4,5-dihydroxy-2,3-pentanedione (DPD), which cyclizes to form AI-2. Synthetic DPD also increased the frequency of stops in wild-type H. pylori, similar to the behaviour induced by the known chemorepellent HCl. We found that whereas mutants lacking the chemoreceptor genes tlpA, tlpC or tlpD responded to an exogenous source of synthetic DPD, the chemoreceptor mutant tlpB was non-responsive to a gradient or uniform distribution of the chemical. Furthermore, a double mutant lacking both tlpB and luxS exhibited chemotactic behaviour similar to the tlpB single mutant, whereas a double mutant lacking both tlpB and the chemotransduction gene cheA behaved like a nonchemotactic cheA single mutant, supporting the model that tlpB functions in a signalling pathway downstream of luxS and upstream of cheA. We conclude that H. pylori perceives LuxS-produced AI-2 as a chemorepellent via the chemoreceptor TlpB.

Non-destructive X-ray analysis of Arabidopsis embryo mutants

1993 ◽  
Vol 3 (3) ◽  
pp. 167-170 ◽  
Author(s):  
R. J. Bino ◽  
J. W. Aartse ◽  
W. J. van der Burg
Keyword(s):  
Arabidopsis Thaliana ◽  
Double Mutant ◽  
Embryo Morphology ◽  
Wild Type ◽  
X Ray ◽  
Non Destructive ◽  
Mature Seeds

AbstractX-radiography is a simple, rapid and non-destructive method for analysing the morphology of embryos in dry, mature seeds of Arabidopsis thaliana. In wild type seeds, the cotyledons, hypocotyl and radicle tip can be readily distinguished. In seeds of the mutant types knolle, keule, and the double mutant keulelgnom, aberrations in embryo morphology can be visualized. X-radiography may therefore be useful in the isolation of embryo mutants from Arabidopsis seed samples.

scholarly journals An msbB Homologue Carried in Plasmid pO157 Encodes an Acyltransferase Involved in Lipid A Biosynthesis in Escherichia coli O157:H7

2004 ◽  
Vol 72 (2) ◽  
pp. 1174-1180 ◽  
Author(s):  
Sang-Hyun Kim ◽  
Wenyi Jia ◽  
Russell E. Bishop ◽  
Carlton Gyles
Keyword(s):  
Escherichia Coli ◽  
Mutant Strain ◽  
Double Mutant ◽  
Lipid A ◽  
Escherichia Coli O157 ◽  
Wild Type ◽  
Single Mutant ◽  
Double Mutant Strain ◽  
Mutant Strains ◽  
Lipid A Biosynthesis

ABSTRACT Escherichia coli O157:H7 carries a chromosomal msbB1 and a plasmid-encoded msbB2 gene. We characterized msbB2 function as a homologue of msbB1 by examination of wild-type organisms and mutant strains that lacked functional msbB1, msbB2, and both msbB1 and msbB2. The msbB double-mutant strain generated pentaacyl lipid A, while the single-mutant strains synthesized hexaacyl lipid A. Complementation with overexpressed msbB2 converted pentaacyl into hexaacyl lipid A in the double-mutant strain. The transcription of both msbB genes occurred simultaneously. Lack of MsbB2 activity slightly increased the microheterogeneity of the lipid A species. These results suggest that the msbB2 gene plays a role not only in the routine generation of fully hexaacylated lipid A but also in suppressing the microheterogeneity of lipid A species, the endotoxic determinant of the organism.

scholarly journals Identification of an arabinopyranosyltransferase fromPhyscomitrella patensinvolved in the synthesis of the hemicellulose xyloglucan

2017 ◽  
Author(s):  
Lei Zhu ◽  
Murali Dama ◽  
Markus Pauly
Keyword(s):  
Arabidopsis Thaliana ◽  
Transgenic Plants ◽  
Linkage Analysis ◽  
Double Mutant ◽  
Physcomitrella Patens ◽  
Proper Function ◽  
Side Chain ◽  
Glycosidic Linkage ◽  
Nmr Analysis ◽  
Wild Type

AbstractThe hemicellulose xyloglucan consists of a backbone of a β-1,4 glucan substituted with xylosyl moieties and many other, diverse sidechains that are important for its proper function. Many, but not all glycosyltransferases involved in the biosynthesis of xyloglucan have been identified. Here, we report the identification of an hitherto elusive xyloglucan:arabinopyranosyltransferase. This glycosyltransferase was isolated from the mossPhyscomitrella patens, where it acts as aXyloglucan “D”-side-chainTransferase (XDT). Heterologous expression ofXDTin theArabidopsis thalianadouble mutantmur3.1 xlt2, where xyloglucan consists of a xylosylated glucan without further glycosyl substituents, results in the production of the arabinopyranose-containing “D” side chain as characterized by oligosaccharide mass profiling, glycosidic linkage analysis, and NMR analysis. In addition, expression of a relatedPhyscomitrellaglycosyltransferase hortholog ofXLT2leads to the production of the galactose-containing “L” side chain. The presence of the “D” and “L” xyloglucan side chains inPpXDT mur3.1 xlt2andPpXLT2 mur3.1 xlt2transgenic plants, respectively, rescue the dwarfed phenotype of untransformedmur3.1 xlt2mutants to nearly wild-type height. Expression ofPpXDTandPpXLT2in the Arabidopsismur3.1 xlt2mutant also enhanced root growth.

scholarly journals Separate Ion Pathways in a Cl−/H+ Exchanger

2005 ◽  
Vol 126 (6) ◽  
pp. 563-570 ◽  
Author(s):  
Alessio Accardi ◽  
Michael Walden ◽  
Wang Nguitragool ◽  
Hariharan Jayaram ◽  
Carole Williams ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Proton Transfer ◽  
Transport Mechanism ◽  
Double Mutant ◽  
Wild Type ◽  
Extracellular Solution ◽  
X Ray ◽  
Single Mutant ◽  
Cl Transport ◽  
Alternating Access

CLC-ec1 is a prokaryotic CLC-type Cl−/H+ exchange transporter. Little is known about the mechanism of H+ coupling to Cl−. A critical glutamate residue, E148, was previously shown to be required for Cl−/H+ exchange by mediating proton transfer between the protein and the extracellular solution. To test whether an analogous H+ acceptor exists near the intracellular side of the protein, we performed a mutagenesis scan of inward-facing carboxyl-bearing residues and identified E203 as the unique residue whose neutralization abolishes H+ coupling to Cl− transport. Glutamate at this position is strictly conserved in all known CLCs of the transporter subclass, while valine is always found here in CLC channels. The x-ray crystal structure of the E203Q mutant is similar to that of the wild-type protein. Cl− transport rate in E203Q is inhibited at neutral pH, and the double mutant, E148A/E203Q, shows maximal Cl− transport, independent of pH, as does the single mutant E148A. The results argue that substrate exchange by CLC-ec1 involves two separate but partially overlapping permeation pathways, one for Cl− and one for H+. These pathways are congruent from the protein's extracellular surface to E148, and they diverge beyond this point toward the intracellular side. This picture demands a transport mechanism fundamentally different from familiar alternating-access schemes.

scholarly journals Survival, DNA-breakdown and induction of prophage lambda in aEscherichia coliK12recAuvrBdouble mutant

1969 ◽  
Vol 14 (3) ◽  
pp. 291-307 ◽  
Author(s):  
I. M. Hertman
Keyword(s):  
Mitomycin C ◽  
Ultraviolet Light ◽  
Double Mutant ◽  
Similar Rate ◽  
Complete Medium ◽  
Wild Type ◽  
Single Mutant ◽  
Pyrimidine Dimers ◽  
Cellular Dna ◽  
K 12

Cellular functions of a double mutant ofEscherichia coliK 12 deficient in recombination (recA) and defective in excision of pyrimidine dimers (uvrB) have been compared to those of isogenicrecAoruvrBsingle mutants and ‘wild type’ bacteria. A combined effect of the two mutations on cell survival both under normal conditions of growth and after exposure to ultraviolet light or mitomycin C was demonstrated. The ratio of optical density to the number of colony formers in growing cultures of the double mutant is three times greater than in similar cultures of therecAsingle mutant and 9 times greater than in eitheruvrBor in ‘wild type’ cultures. The doubling time in growingrecA uvrBcultures is 90 min, compared to 60 min, for therecAsingle mutant and 40 min for theuvrBsingle mutant and ‘wild type’ bacteria. Growing cultures ofrecA uvrB(λcI857) bacteria contain a substantial fraction of cells which are unable to form colonies at 32 °C, but produce phage when heated to 42 °C. No such cells were found in cultures of the single mutants or the ‘wild type’ bacteria lysogenic for λc1857. The double mutant is 10 times more sensitive to ultraviolet light and twice more sensitive to mitomycin C than therecAsingle mutant. In contrast torecAbacteria, exposure of the double mutant to mitomycin C induces little additional breakdown of cellular DNA. Induction of the prophage by mitomycin C is, however, prevented in bothrecA uvrB(λ) andrecA(λ) bacteria. Exposure to mitomycin C creates conditions which render the prophage inducible by a newly transducedree Agene. This effect of mitomycin C persists and can be revealed in complete medium at 37 °C after 100 min of incubation. The decay of the prophage, in cells exposed to mitomycin C, proceeds at a similar rate in both the double mutant and therecAsingle mutant. The inability ofrecAlysogens to be induced to phage production is discussed in the light of the present findings.

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