scholarly journals Genetic Dissection Defines the Roles of Elsinochrome Phytotoxin for Fungal Pathogenesis and Conidiation of the Citrus Pathogen Elsinoë fawcettii

2008 ◽  
Vol 21 (4) ◽  
pp. 469-479 ◽  
Author(s):  
Hui-Ling Liao ◽  
Kuang-Ren Chung
Keyword(s):  
Polyketide Synthase ◽  
Functional Characterization ◽  
Chemical Properties ◽  
Fungal Pathogenesis ◽  
Genetic Dissection ◽  
Wild Type ◽  
Rough Lemon ◽  
Mutant Phenotypes ◽  
Axenic Conditions

Elsinochrome pigments produced by many phytopathogenic Elsinoë spp. are nonhost-selective toxins which react with oxygen molecules after light activation to produce highly toxic reactive oxygen species. The structures and chemical properties of four derivatives are well known. However, the biological roles of elsinochromes in fungal pathogenesis are poorly understood. Many isolates of Elsinoë fawcettii causing citrus scab are able to produce elsinochromes under axenic conditions. In this article, we report the cloning, expression, and functional characterization of the polyketide synthase-encoding gene, EfPKS1, which we show is required for the production of elsinochromes and fungal pathogenesis. Targeted disruption of EfPKS1 in E.fawcettii completely abrogated elsinochrome production, drastically reduced conidiation, and significantly decreased lesion formation on rough lemon leaves. All mutant phenotypes were restored to the wild type in fungal strains expressing a functional copy of EfPKS1. Accumulation of the EfPKS1 transcript and elsinochromes by a wild-type strain appears to be coordinately regulated by light, nutrients, and pH. The results indicate that the product of EfPKS1 is involved in the biosynthesis of elsinochromes via a fungal polyketide pathway, and that elsinochromes play an important role in fungal pathogenesis.

Functional characterization of the H+/K+ ATPase in wild type and gastrin knock-out mice

2007 ◽  
Vol 45 (05) ◽  
Author(s):  
A Schnur ◽  
P Hegyi ◽  
V Venglovecz ◽  
Z Rakonczay ◽  
I Ignáth ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Wild Type ◽  
Knock Out ◽  
Knock Out Mice

scholarly journals The Mutant Phenotype Associated With P-Element Alleles of the vestigial Locus in Drosophila melanogaster May Be Caused by a Readthrough Transcript Initiated at the P-Element Promoter

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1665-1672 ◽  
Author(s):  
Ross B Hodgetts ◽  
Sandra L O'Keefe
Keyword(s):  
Rna Secondary Structure ◽  
Insertion Site ◽  
Large Body ◽  
P Element ◽  
Wild Type ◽  
Subtle Difference ◽  
Pronounced Difference ◽  
Internal Repeat ◽  
Mutant Phenotypes

Abstract We report here the isolation of a new P-element-induced allele of the vestigial locus vg2a33, the molecular characterization of which allows us to propose a unifying explanation of the phenotypes of the large number of vestigial P-element alleles that now exists. The first P-element allele of vestigial to be isolated was vg21, which results in a very weak mutant wing phenotype that is suppressed in the P cytotype. By destabilizing vg2a33 in a dysgenic cross, we isolated the vg2a33 allele, which exhibits a moderate mutant wing phenotype and is not suppressed by the P cytotype. The new allele is characterized by a 46-bp deletion that removes the 3′-proximal copy of the 11-bp internal repeat from the P element of vg21. To understand how this subtle difference between the two alleles leads to a rather pronounced difference in their phenotypes, we mapped both the vg and P-element transcription units present in wild type and mutants. Using both 5′-RACE and S1 protection, we found that P-element transcription is initiated 19 bp farther upstream than previously thought. Using primer extension, the start of vg transcription was determined to lie 435 bp upstream of the longest cDNA recovered to date and upstream of the P-element insertion site. Our discovery that the P element is situated within the first vg exon has prompted a reassessment of the large body of genetic data on a series of alleles derived from vg21. Our current hypothesis to explain the degree of variation in the mutant phenotypes and their response to the P repressor invokes a critical RNA secondary structure in the vg transcript, the formation of which is hindered by a readthrough transcript initiated at the P-element promoter.

scholarly journals Functional characterization of the rod visual pigment of the echidna (Tachyglossus aculeatus), a basal mammal

2012 ◽  
Vol 29 (4-5) ◽  
pp. 211-217 ◽  
Author(s):  
CONSTANZE BICKELMANN ◽  
JAMES M. MORROW ◽  
JOHANNES MÜLLER ◽  
BELINDA S.W. CHANG
Keyword(s):  
Half Life ◽  
Functional Characterization ◽  
Egg Laying ◽  
Sensory Transduction ◽  
Wild Type ◽  
Functional Variation ◽  
Bovine Rhodopsin ◽  
Tachyglossus Aculeatus

AbstractMonotremes are the most basal egg-laying mammals comprised of two extant genera, which are largely nocturnal. Visual pigments, the first step in the sensory transduction cascade in photoreceptors of the eye, have been examined in a variety of vertebrates, but little work has been done to study the rhodopsin of monotremes. We isolated the rhodopsin gene of the nocturnal short-beaked echidna (Tachyglossus aculeatus) and expressed and functionally characterized the protein in vitro. Three mutants were also expressed and characterized: N83D, an important site for spectral tuning and metarhodopsin kinetics, and two sites with amino acids unique to the echidna (T158A and F169A). The λmax of echidna rhodopsin (497.9 ± 1.1 nm) did not vary significantly in either T158A (498.0 ± 1.3 nm) or F169A (499.4 ± 0.1 nm) but was redshifted in N83D (503.8 ± 1.5 nm). Unlike other mammalian rhodopsins, echidna rhodopsin did react when exposed to hydroxylamine, although not as fast as cone opsins. The retinal release rate of light-activated echidna rhodopsin, as measured by fluorescence spectroscopy, had a half-life of 9.5 ± 2.6 min−1, which is significantly shorter than that of bovine rhodopsin. The half-life of the N83D mutant was 5.1 ± 0.1 min−1, even shorter than wild type. Our results show that with respect to hydroxylamine sensitivity and retinal release, the wild-type echidna rhodopsin displays major differences to all previously characterized mammalian rhodopsins and appears more similar to other nonmammalian vertebrate rhodopsins such as chicken and anole. However, our N83D mutagenesis results suggest that this site may mediate adaptation in the echidna to dim light environments, possibly via increased stability of light-activated intermediates. This study is the first characterization of a rhodopsin from a most basal mammal and indicates that there might be more functional variation in mammalian rhodopsins than previously assumed.

scholarly journals Functional characterization of wild-type and mutant human sialin

2004 ◽  
Vol 23 (23) ◽  
pp. 4560-4570 ◽  
Author(s):  
Pierre Morin ◽  
Corinne Sagné ◽  
Bruno Gasnier
Keyword(s):  
Functional Characterization ◽  
Wild Type

scholarly journals 2066 Functional characterization of mutant BRCA1

2018 ◽  
Vol 2 (S1) ◽  
pp. 13-13
Author(s):  
John Barrows ◽  
David Long
Keyword(s):  
Functional Characterization ◽  
Coiled Coil ◽  
Wild Type ◽  
Coiled Coil Region ◽  
Egg Extracts ◽  
Study Population ◽  
Xenopus Egg ◽  
Xenopus Egg Extracts

OBJECTIVES/SPECIFIC AIMS: The objective of this work is to determine the mechanistic consequences of BRCA1 mutants in inter-strand crosslink (ICL) repair. METHODS/STUDY POPULATION: Our lab uses Xenopus egg extracts to study ICL repair. These extracts can be depleted of endogenous BRCA1 by immunoprecipitation. The goal of this work is to rescue endogenous depletion with in vitro translated, wild type BRCA1. Once achieved, we can supplement the depleted extract with BRCA1 mutants to access their function in ICL repair. RESULTS/ANTICIPATED RESULTS: We hypothesize that the BRCT and RING domain mutations will abrogate ICL repair, while mutations in the coiled coil region will not affect repair. DISCUSSION/SIGNIFICANCE OF IMPACT: These findings will have an immense impact on the understanding of BRCA1 domains. Importantly these results will spur personalized therapy of BRCA1 mutants by showing which domains are sensitive to cross-linking agents.

scholarly journals Crystal Structures and Functional Characterization of Wild-Type CYP101D1 and Its Active Site Mutants

Biochemistry ◽  
2013 ◽  
Vol 52 (49) ◽  
pp. 8898-8906 ◽  
Author(s):  
Dipanwita Batabyal ◽  
Thomas L. Poulos
Keyword(s):  
Crystal Structures ◽  
Active Site ◽  
Functional Characterization ◽  
Wild Type ◽  
Active Site Mutants

Functional Characterization of Wild-type and 49 CYP2D6 Allelic Variants for N-Desmethyltamoxifen 4-Hydroxylation Activity

2014 ◽  
Vol 29 (5) ◽  
pp. 360-366 ◽  
Author(s):  
Yuka Muroi ◽  
Takahiro Saito ◽  
Masamitsu Takahashi ◽  
Kanako Sakuyama ◽  
Yui Niinuma ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Wild Type ◽  
Allelic Variants ◽  
Hydroxylation Activity

Functional characterization of a veA-dependent polyketide synthase gene in Aspergillus flavus necessary for the synthesis of asparasone, a sclerotium-specific pigment

2014 ◽  
Vol 64 ◽  
pp. 25-35 ◽  
Author(s):  
Jeffrey W. Cary ◽  
Pamela Y. Harris-Coward ◽  
Kenneth C. Ehrlich ◽  
José Diana Di Mavungu ◽  
Svetlana V. Malysheva ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Polyketide Synthase ◽  
Functional Characterization ◽  
Polyketide Synthase Gene

Physiological and genetic characterization of the osmotic stress response in Bacillus subtilis

1994 ◽  
Vol 40 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Sandra M. Ruzal ◽  
Carmen Sanchez-Rivas
Keyword(s):  
Bacillus Subtilis ◽  
Osmotic Stress ◽  
Stationary Phase ◽  
Resistant Mutant ◽  
Wild Type ◽  
Osmotic Stress Response ◽  
Mutant Phenotypes ◽  
Physiological Variations ◽  
Growth Adaptation

Bacillus subtilis cultures submitted to an osmotic upshock (1.5 M NaCl) lysed unless stationary phase had been reached. Several physiological variations were observed, such as delayed growth (adaptation), a filamentous bacterial appearance, RecA-dependent osmoresistance (SOS), and cross-induction by a previous stress (heat shock). Osmoresistance and sporulation seem to share pathways of regulation such as inhibition in the presence of glucose and glutamine and derepression in a catabolite-resistant mutant such as degUh. However, spores were not obtained on hypertonic media. Mutants of later sporulation stages (spoII, spoIII) presented a response similar to that of the wild-type parent, indicating that both processes probably shared early controls. Null mutations in any of the known key modulators of sporulation (spoOA or degU) resulted in similar levels of osmosensitivity. Sensor mutations in kinA and degS also led to strains with altered responses, the kinA mutant being even more osmosensitive than the degS mutant. Several spoOA mutant phenotypes are due to this gene's control of abrB, a regulator of stationary-phase events, and an abrB mutation relieved the osmosensitivity of the spoOA-containing mutant but had no effect on a wild-type strain.Key words: Bacillus subtilis, osmotic stress, sporulation.

scholarly journals Ectopic expression and functional characterization of type III polyketide synthase mutants from Emblica officinalis Gaertn

2016 ◽  
Vol 35 (10) ◽  
pp. 2077-2090 ◽  
Author(s):  
Girija Aiswarya ◽  
Vijayanathan Mallika ◽  
Luis A. J. Mur ◽  
Eppurathu Vasudevan Soniya
Keyword(s):  
Polyketide Synthase ◽  
Functional Characterization ◽  
Ectopic Expression ◽  
Emblica Officinalis ◽  
Type Iii Polyketide Synthase ◽  
Type Iii
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