New Insights into 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase Phylogeny, Evolution and Ecological Significance

Abstract

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.

Plant growth-promoting actinobacteria: a new strategy for enhancing sustainable production and protection of grain legumes

“…Characterization of this enzyme effects on stress management is observed for the past two decades, and now considered as a key phenomenon of PGP traits (Glick 1995). Many of the actinobacteria are shown to produce ACC deaminase such as Streptomyces, Amycolatopsis, Nocardia, Mycobacterium, Rhodococcus, and others (Nascimento et al 2014). Siddikee et al (2010) isolated several halotolerant actinobacteria strains with ACC deaminase, from the soil of barren fields and the rhizosphere of naturally growing halophytic plants and found that they can increase canola plant growth.…”

Bacterial Modulation of Plant Ethylene Levels

“…A complete description of the phylogeny and evolution of the genes encoding acdS and its major regulatory gene, acdR, has been recently elaborated (Bruto et al, 2014;Nascimento et al, 2014). Information regarding acdS/acdR sequences must be considered together with the habitat, the origin, and the enzymatic activity of completely sequenced bacterial strains to obtain a comprehensive view.…”

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

“…Thus, microorganisms that can produce IAA and utilize ACC may have a competitive advantage over other soil microorganisms (Glick et al, 1998, Stearns et al, 2012. It is know that ACCD modulates ACC metabolism and is related to plant growth promotion and microorganism's developmental processes (Nascimento et al, 2014) and thus protecting the plant from stress (Subramanian et al, 2015).…”

“…Additionally, recent results suggest a considerable degree of horizontal ACCD gene transfer events (Nascimento et al, 2014). Hence, exploration of more ACCD gene from diverse bacterial sources and in depth understanding of the function of this enzyme especially in plant physiology signifies its importance.…”

“…Hence, exploration of more ACCD gene from diverse bacterial sources and in depth understanding of the function of this enzyme especially in plant physiology signifies its importance. This may be the key molecule in a variety of important agricultural and biotechnological applications of ACCD genes and their expression (Nascimento et al, 2014).…”