Nascimento Francisco X, Rossi Márcio J, Soares Cláudio R F S, McConkey Brendan J, Glick Bernard R
Universidade Federal de Santa Catarina, Departamento de Microbiologia, Laboratório de Microbiologia do Solo, Florianópolis SC, Brazil.
University of Waterloo, Department of Biology, Waterloo, Ontario, Canada.
PLoS One. 2014 Jun 6;9(6):e99168. doi: 10.1371/journal.pone.0099168. eCollection 2014.
The main objective of this work is the study of the phylogeny, evolution and ecological importance of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, the activity of which represents one of the most important and studied mechanisms used by plant growth-promoting microorganisms. The ACC deaminase gene and its regulatory elements presence in completely sequenced organisms was verified by multiple searches in diverse databases, and based on the data obtained a comprehensive analysis was conducted. Strain habitat, origin and ACC deaminase activity were taken into account when analyzing the results. In order to unveil ACC deaminase origin, evolution and relationships with other closely related pyridoxal phosphate (PLP) dependent enzymes a phylogenetic analysis was also performed. The data obtained show that ACC deaminase is mostly prevalent in some Bacteria, Fungi and members of Stramenopiles. Contrary to previous reports, we show that ACC deaminase genes are predominantly vertically inherited in various bacterial and fungal classes. Still, results suggest a considerable degree of horizontal gene transfer events, including interkingdom transfer events. A model for ACC deaminase origin and evolution is also proposed. This study also confirms the previous reports suggesting that the Lrp-like regulatory protein AcdR is a common mechanism regulating ACC deaminase expression in Proteobacteria, however, we also show that other regulatory mechanisms may be present in some Proteobacteria and other bacterial phyla. In this study we provide a more complete view of the role for ACC deaminase than was previously available. The results show that ACC deaminase may not only be related to plant growth promotion abilities, but may also play multiple roles in microorganism's developmental processes. Hence, exploring the origin and functioning of this enzyme may be the key in a variety of important agricultural and biotechnological applications.
这项工作的主要目标是研究1-氨基环丙烷-1-羧酸（ACC）脱氨酶的系统发育、进化及其生态重要性，该酶的活性是促进植物生长的微生物所采用的最重要且研究最多的机制之一。通过在不同数据库中进行多次搜索，验证了完全测序生物中ACC脱氨酶基因及其调控元件的存在，并基于获得的数据进行了全面分析。在分析结果时考虑了菌株的栖息地、来源和ACC脱氨酶活性。为了揭示ACC脱氨酶的起源、进化以及与其他密切相关的依赖磷酸吡哆醛（PLP）的酶之间的关系，还进行了系统发育分析。获得的数据表明，ACC脱氨酶在一些细菌、真菌和不等鞭毛类生物中最为普遍。与先前的报道相反，我们表明ACC脱氨酶基因在各种细菌和真菌类群中主要是垂直遗传的。不过，结果表明存在相当程度的水平基因转移事件，包括跨界转移事件。还提出了ACC脱氨酶起源和进化的模型。本研究还证实了先前的报道，即类Lrp调控蛋白AcdR是调节变形菌门中ACC脱氨酶表达的常见机制，然而，我们也表明在一些变形菌门和其他细菌门中可能存在其他调控机制。在本研究中，我们对ACC脱氨酶的作用提供了比以前更完整的观点。结果表明，ACC脱氨酶不仅可能与促进植物生长的能力有关，还可能在微生物的发育过程中发挥多种作用。因此，探索这种酶的起源和功能可能是各种重要农业和生物技术应用的关键。
