Peroxisomes: Endosymbiotic Organelles without a Genome?

过氧化物酶体：没有基因组的内共生细胞器？

• 批准号: 9318594
• 负责人: Jeffrey Palmer
• 金额: $ 22.5万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1997-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9318594&HistoricalAwards=false
• 关键词: Peroxisomes; Endosymbiotic; Organelles; without; Genome

9318594 PALMER The peroxisome is a small, membrane-bound organelle found in the cells of all animals and other higher organisms. Peroxisomes lack a genome of their own, but a number of important biochemical reactions and enzymes (coded for by nuclear genes) occur within the peroxisome, and a large number of human diseases, mostly lethal, are caused by defects in peroxisomal function. Although much is known about the function of the peroxisome, we know nothing about its origin. This project seeks to remedy this situation by gathering evidence to test the two competing hypotheses for the origin of the peroxisome: 1) that it arose by internal compartmentation of a subset of metabolic enzymes, or 2) that, like chloroplasts and mitochondria, it arose endosymbiotically, i.e. by the permanent uptake of a bacterium (which turned into the peroxisome) by a primitive eukaryotic cell. In preliminary studies, we have identified four peroxisomal proteins that show provocatively high levels of similarity to bacterial homologs, and which thus provide suggestive evidence in support of hypothesis #2. To provide a rigorous test of the endosymbiotic hypothesis of peroxisomal origins, we will sequence and phylogenetically analyze the genes for each of these four proteins from about 20 diverse bacteria and from several representative eukaryotes. In addition, we will sequence several other genes, such as those encoding for the heat shock proteins, as they become available to this project. In the absence of a peroxisomal genome, it is imperative that congruent data be sought for as many different peroxisomal proteins as possible. The strongest answer to the question "Is the peroxisome an endosymbiont?" will come if multiple nuclear genes for peroxisomal proteins all trace back to the same place within a bacterial phylogenetic tree, a place distinct from that of both mitochondria and plastids. If such an answer is forthcoming, it would provide a rationale for reassessing the possibility that a residual perox isomal genome might still lurk in some eukaryotes. This project is being jointly funded by the Systematic and Population Biology programs of the Division of Environmental Biology (DEB) and the Metabolic Biochemistry program of the Division of Molecular and Cellular Biosciences (MCB). %%% Peroxisomes are small cellular organelles that are very important to the metabolism and effective functioning of cells. Several lethal human diseases are attributed to defects in peroxisomal functioning. This study will investigate the origin of these important organelles. ***

小行星9318594 过氧化物酶体是存在于所有动物和其他高等生物细胞中的一种小的膜结合细胞器。 过氧化物酶体缺乏自己的基因组，但许多重要的生化反应和酶（由核基因编码）发生在过氧化物酶体内，并且许多人类疾病（大多数是致命的）是由过氧化物酶体功能缺陷引起的。 虽然我们对过氧化物酶体的功能了解很多，但对它的起源却一无所知。 该项目试图通过收集证据来检验关于过氧化物酶体起源的两种相互竞争的假设来纠正这种情况：1）它是由代谢酶的一个子集的内部区室化产生的，或者2）它像叶绿体和线粒体一样，是内共生产生的，即通过原始真核细胞永久吸收细菌（变成过氧化物酶体）。 在初步研究中，我们已经确定了四种过氧化物酶体蛋白，它们与细菌同源物显示出非常高的相似性，从而为支持假设#2提供了暗示性证据。 为了提供一个严格的测试过氧化物酶体起源的内共生假说，我们将测序和基因组学分析这四种蛋白质的基因从大约20种不同的细菌和几个代表性的真核生物。 此外，我们将测序其他几个基因，如编码热休克蛋白的基因，因为它们可用于本项目。 在缺乏过氧化物酶体基因组的情况下，必须为尽可能多的不同过氧化物酶体蛋白寻找一致的数据。 对“过氧化物酶体是内共生体吗？如果过氧化物酶体蛋白的多个核基因都可以追溯到细菌系统发育树中的同一个位置，一个与线粒体和质体不同的位置，那么“将出现。 如果这样的答案是即将到来的，它将提供一个重新评估的可能性，剩余的过氧化物酶同工酶基因组可能仍然潜伏在一些真核生物的理由。 该项目由环境生物学部（DEB）的系统和种群生物学计划以及分子和细胞生物科学部（MCB）的代谢生物化学计划共同资助。 %%% 过氧化物酶体是一种小的细胞器，对细胞的代谢和有效功能非常重要。 几种致命的人类疾病归因于过氧化物酶体功能的缺陷。 本研究将探讨这些重要细胞器的起源。 ***