Identification and characterization of a soybean protein with adenylyl cyclase activity
Enetia Desberia Bobo, Katlego Selaelo Sehlabane, Tshegofatso Bridget Dikobe, Mutsa Monica Takundwa, David Tonderai Kawadza and Oziniel Ruzvidzo
North-West University, Mmabatho, North West, South Africa.
Soybean [Glycine max (L.) Merrill] is a high value leguminous crop characterized by its excellent protein content and ability to improve soil quality through nitrogen fixation. Whereas this plant has attractive human and animal feed attributes in addition to its pharmaceutical and industrial uses, its growth and yield are severely affected by drought. Thus any research aimed at understanding the genome response of this plant to drought and other related environmental stress factors would be worthwhile. In plants, in general, second messengers have a key role in linking and coordinating environmental stimuli to cellular communication and responses. One group of such messengers are adenylyl cyclases (ACs) and their catalytic product 3′,5′-cyclic adenosine monophosphate (cAMP), involved in plant growth, cell division, reproduction, development and response to stress. However, while ACs have been reported in some plant species such as Arabidopsis and maize, their presence together with their cAMP-dependent systems in G. max have largely remained unavailable. Fortunately, a putative molecule, Glyma.07G251000 (accession number: XP_003529590), with a predicted function as an AC in G. max has at some point been reported. This molecule harbors a domain annotated AC catalytic center and therefore, was herein targeted for study. In order to characterize the Glyma.07G251000, we cloned and expressed it, followed by purification of the resultant recombinant protein (GmAC). When tested in vitro for AC activity, the GmAC protein showed a Mn2+-dependent activity that is positively enhanced by calcium. GmAC also complemented the AC-deficiency (cyaA mutation) of an SP850 mutant strain when expressed in Escherichia coli. When analysed by a web-based approach system, the GmAC protein was found to be co-expressed and co-regulated with various other proteins responsible for early plant development and stress response, strongly suggesting that it has a central role in these two key cellular processes. In addition, the GmAC protein conferred stress resistance to EXPRESS BL21 (DE3) pLysS DUOs cells when expressed in these host cells under salt (200 mM NaCl) and oxidative stress (0.2 mM H2O2). Conceivably, our findings showed that GmAC is an AC protein with a role in early plant development and stress response.
1. GmAC is an adenylyl cyclase and the first ever such protein to be identified in soybean.
2. GmAC confers stress tolerance to Escherichia coli and is co-expressed/co-regulated with other soybean proteins responsible for early plant development and stress response.