Molecular profiling and functional characterization of a novel adenylyl cyclase protein in two different varieties of soybean

Abstract

Adenylyl cyclases (ACs) are a special group of enzymes that catalyze formation of the second messenger molecule, 3′,5′-cyclic adenosine monophosphate (cAMP) from 5′-adenosine triphosphate (ATP). In plants, cAMP controls various cellular and physiological processes that are key for survival, growth and development. Some of such processes include control of the cell cycle in tobacco, transport of sodium ions via the voltage-independent channels (VICs) in Arabidopsis thaliana, stomatal closure in Vicia faba, growth of pollen tubes in Agapanthus umbellatus, Lilium longiflorum and Zea mays, activation of the phenylalanine ammonia lyase (PAL) enzyme in French beans and regulation of the phenylpropanoid pathway in A. thaliana. cAMP is also involved in stress response primarily via the cyclic nucleotide-gated channels (CNGCs). Apparently, while a number of ACs have been identified in plants and their cAMP-dependent activities reported, no study to date has attempted to work and/or report on AC activities that are variety-specific for a particular plant species. Therefore, considering the importance of soybean (Glycine max) as a source of food, feed, oils, fuels and nitrogen, the present work is an attempt to answer this question. This was achived by isolating fractions of a GmAC protein, annotated to be an AC in this legume, followed by assessment of the possible variety-specific activities. The stated GmAC fractions were specifically isolated from the NS 5909R variety, known to be drought tolerant and PN 1532A variety, known to be pest resistant. The isolated protein fractions were then cloned (Chapter 2) followed by their comparative assessment for endogenous activity (Chapter 3), in vitro activity (Chapter 4), complementation activity (Chapter 5) and functional role in stress response (Chapter 6). Thrillingly, across all these various assessments and evaluations, we found that essentially, no significant differences between the two studied protein fractions existed to report and/or establish a possible variety-specific activity for the GmAC protein. Notably, further analysis of the two studied protein fractions through sequencing and sequence analysis (Chapter 7), showed that the catalytic center of

nearly all ACs, including GmAC, is highly conserved thus explaining why the two studied protein fractions herein could not show any variety-specific activity.