{"title":"El sistema ubicuitina/proteasoma en la interacción planta-patógeno","authors":"Mario Rocha-Sosa","doi":"10.1016/S1405-888X(13)72083-7","DOIUrl":"10.1016/S1405-888X(13)72083-7","url":null,"abstract":"<div><p>Ubiquitin (Ub) is a small protein used to label proteins by eukaryotic organisms; in most cases labeled proteins will be degraded afterwards. Ubiquitination occurs in three sequential steps through reactions requiring the action of the ubiquitin-activating enzyme, the ubiquitin-conjugating enzyme and the ubiquitin ligase. After this, the target protein will follow a different fate according to ubiquitination topology. Most ubiquitinated proteins will be degraded in the 2.5 M protein complex termed the 26S proteasome. Plants employ this mechanism of regulated protein degradation to modulate developmental and growing processes as well as to respond to detrimental situations, like water deficit or pathogen attack. During the evolution plants have developed different strategies to cope against pathogen infection, however these organisms have acquired tools that allow them to counteract plant defense mechanisms. Among different ways to undermine plant resistance pathways, pathogens have now the ability to manipulate the Ub/proteasome system to efficiently infect them.</p></div>","PeriodicalId":31507,"journal":{"name":"TIP Revista Especializada en Ciencias QuimicoBiologicas","volume":"16 2","pages":"Pages 121-131"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1405-888X(13)72083-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84148271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Transformación de la aflatoxina B1 de alimentos, en el cancerígeno humano, aducto AFB1-ADN","authors":"Magda Carvajal","doi":"10.1016/S1405-888X(13)72082-5","DOIUrl":"10.1016/S1405-888X(13)72082-5","url":null,"abstract":"<div><p>Aflatoxins (AF) are secondary toxic metabolites formed mainly by the molds <em>Aspergillus flavus</em> and <em>A. parasiticus</em>; they are potent mutagens and carcinogens of foods, and human exposure to them is continuous. AF bind to DNA, RNA and proteins forming AFB<sub>1</sub>-DNA adducts that accumulate for years and damage from viruses to humans. To identify and quantify the chemical reactions and molecular biology of these adducts is of primary importance because they are long-term biomarkers validated as a source of mutagenicity and risk of cancer in animals and humans. The cytochrome P<sub>450</sub> activates AF as an unstable molecule called 8,9 AFB<sub>1</sub> epoxide, that binds mainly to the N<sup>7</sup> of the guanine nucleotide forming adducts that are the active carcinogens themselves and, as biomarkers, an objective measure of human exposure to environmental carcinogens. Adducts represent an integration of exposure, absorption, distribution, metabolism, DNA repair, and cell turnover. The different issues presented here are the formation of AFB<sub>1</sub>-DNA adducts, in vitro and <em>in vivo</em> studies, dietary AFB<sub>1</sub> exposure, effects, development of human cancer and mutations in the p53 tumor suppressor gene, the effect of diet, routes of exposure, vitamins, kinds of AFB<sub>1</sub>-DNA adducts, methodology used for their study and their control.<span></span></p></div>","PeriodicalId":31507,"journal":{"name":"TIP Revista Especializada en Ciencias QuimicoBiologicas","volume":"16 2","pages":"Pages 109-120"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1405-888X(13)72082-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74117954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}