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首页> 外文期刊>Molecular phylogenetics and evolution >The phylogeny and evolution of deoxyribonuclease II: An enzyme essential for lysosomal DNA degradation
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The phylogeny and evolution of deoxyribonuclease II: An enzyme essential for lysosomal DNA degradation

机译：脱氧核糖核酸酶II的系统发育和进化：溶酶体DNA降解所必需的酶

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Deoxyribonuclease II (DNase II) is an endonuclease with optimal activity at low pH, localized within the lysosomes of higher eukaryotes. The origin of this enzyme remains in dispute, and its phylogenetic distribution leaves many questions about its subsequent evolutionary history open. Earlier studies have documented its presence in various metazoans, as well as in Dictyostelium, Trichomonas and, anomalously, a single genus of bacteria (Burkholderia). This study makes use of searches,of the genomes of various organisms against known DNase II query sequences, in order to determine the likely point of origin of this enzyme among cellular life forms. Its complete absence from any other bacteria makes prokaryotic origin unlikely. Convincing evidence exists for DNase II homologs in Alveolates such as Paramecium, Heterokonts such as diatoms and water molds, and even tentative matches in green algae. Apparent absences include red algae, plants, fungi, and a number of parasitic organisms. Based on this phylogenetic distribution and hypotheses of eukaryotic relationships, the most probable explanation is that DNase II has been subject to multiple losses. The point of origin is debatable, though its presence in Trichomonas and perhaps in other evolutionarily basal "Excavate" protists such as Reclinomonas, strongly support the hypothesis that DNase II arose as a plesiontorphic trait in eukaryotes. It probably evolved together with phagocytosis, specifically to facilitate DNA degradation and bacteriotrophy. The various absences in many eukaryotic lineages are accounted for by loss of phagotrophic function in intracellular parasites, in obligate autotrophs, and in saprophytes. (c) 2007 Elsevier Inc. All rights reserved.
机译：脱氧核糖核酸酶II（DNase II）是一种核酸内切酶，在低pH下具有最佳活性，位于高等真核生物的溶酶体内。该酶的起源尚有争议，其系统发育分布对其后续的进化历史尚有许多疑问。较早的研究表明，它存在于各种后生动物以及线粒体，滴虫和反常细菌的一个属中（伯克霍尔德氏菌）。这项研究利用针对已知的DNase II查询序列的各种生物的基因组进行搜索，以确定该酶在细胞生命形式中的可能起源点。它完全不存在任何其他细菌，因此不可能是原核生物。令人信服的证据表明，在草履虫（如草履虫）中的DNase II同源物，硅藻和水霉菌等异齿类动物中，甚至在绿藻中也有尝试性的匹配。明显的失踪包括红藻，植物，真菌和许多寄生生物。基于这种系统发育分布和真核生物关系的假设，最可能的解释是DNase II遭受了多次损失。起源点是有争议的，尽管它存在于滴虫和可能在其他进化基础的“挖掘”生物中，例如雷克洛莫纳斯，强烈支持DNase II在真核生物中作为pletortorphic性状出现的假设。它可能与吞噬作用一起进化，特别是促进DNA降解和细菌生长。许多真核生物谱系中各种缺失的原因是细胞内寄生虫，专性自养生物和腐生植物中吞噬营养功能的丧失。 （c）2007 Elsevier Inc.保留所有权利。

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