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Mutant
About: Mutant is a research topic. Over the lifetime, 74520 publications have been published within this topic receiving 3477079 citations.
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TL;DR: In this paper, a map-based approach was used to identify the defective gene in the Arabidopsis JA response mutant jar1-1, which was found to belong to the acyl adenylate-forming firefly luciferase superfamily.
Abstract: Jasmonic acid (JA) and related cyclopentanones are critical plant signaling molecules, but their mode of action at the molecular level is unclear. A map-based approach was used to identify the defective gene in the Arabidopsis JA response mutant jar1-1. JAR1 is 1 of 19 closely related Arabidopsis genes that are similar to the auxin-induced soybean GH3 gene. Analysis of fold predictions for this protein family suggested that JAR1 might belong to the acyl adenylate-forming firefly luciferase superfamily. These enzymes activate the carboxyl groups of a variety of substrates for their subsequent biochemical modification. An ATP-PPi isotope exchange assay was used to demonstrate adenylation activity in a glutathione S-transferase-JAR1 fusion protein. Activity was specific for JA, suggesting that covalent modification of JA is important for its function. Six other Arabidopsis genes were specifically active on indole-3-acetic acid (IAA), and one was active on both IAA and salicylic acid. These findings suggest that the JAR1 gene family is involved in multiple important plant signaling pathways.
616 citations
TL;DR: Mutational analysis showed that the enhanced tumorigenicity was dependent on intrinsic tyrosine kinase activity and was mediated through the carboxyl terminus, suggesting that the biological functions of ΔEGFR are due to low constitutive activation with mitogenic effects amplified by failure to attenuate signaling by receptor down-regulation.
615 citations
TL;DR: The protein encoded by the wild-type p53 proto-oncogene has been shown to suppress transformation, whereas certain mutations that alter p53 become transformation competent, and the inability of the p53 mutant proteins to activate transcription may enable them to be transformation competent.
Abstract: The protein encoded by the wild-type p53 proto-oncogene has been shown to suppress transformation, whereas certain mutations that alter p53 become transformation competent. Fusion proteins between p53 and the GAL4 DNA binding domain were made to anchor p53 to a DNA target sequence and to allow measurement of transcriptional activation of a reporter plasmid. The wild-type p53 stimulated transcription in this assay, but two transforming mutations in p53 were unable to act as transcriptional activators. Therefore, p53 can activate transcription, and transformation-activating mutations result in a loss of function of the p53 protein. The inability of the p53 mutant proteins to activate transcription may enable them to be transformation competent.
614 citations
TL;DR: It is shown that mutant p53 can drive cotranslated wild-type p53 into the mutant conformation, and that oligomers of p53 proteins can be induced to change conformation in a cooperative manner.
613 citations
TL;DR: The genetic characterization of p5cs insertion mutants is described, which indicates that P5CS1 is required for proline accumulation under osmotic stress, and that P4CS2 is insufficient for compensation of developmental defects caused by inactivation of P5 CS2.
Abstract: Delta-1-pyrroline-5-carboxylate synthetase enzymes, which catalyse the rate-limiting step of proline biosynthesis, are encoded by two closely related P5CS genes in Arabidopsis. Transcription of the P5CS genes is differentially regulated by drought, salinity and abscisic acid, suggesting that these genes play specific roles in the control of proline biosynthesis. Here we describe the genetic characterization of p5cs insertion mutants, which indicates that P5CS1 is required for proline accumulation under osmotic stress. Knockout mutations of P5CS1 result in the reduction of stress-induced proline synthesis, hypersensitivity to salt stress, and accumulation of reactive oxygen species. By contrast, p5cs2 mutations cause embryo abortion during late stages of seed development. The desiccation sensitivity of p5cs2 embryos does not reflect differential control of transcription, as both P5CS mRNAs are detectable throughout embryonic development. Cellular localization studies with P5CS-GFP gene fusions indicate that P5CS1 is sequestered into subcellular bodies in embryonic cells, where P5CS2 is dominantly cytoplasmic. Although proline feeding rescues the viability of mutant embryos, p5cs2 seedlings undergo aberrant development and fail to produce fertile plants even when grown on proline. In seedlings, specific expression of P5CS2-GFP is seen in leaf primordia where P5CS1-GFP levels are very low, and P5CS2-GFP also shows a distinct cell-type-specific and subcellular localization pattern compared to P5CS1-GFP in root tips, leaves and flower organs. These data demonstrate that the Arabidopsis P5CS enzymes perform non-redundant functions, and that P5CS1 is insufficient for compensation of developmental defects caused by inactivation of P5CS2.
613 citations