Poster: Enzymology

Abs # 260: Characterizing Acetylcholinesterase in plants

Presenter:	Muralidharan, Mrinalini , minim@asu.edu
Authors	Muralidharan, Mrinalini  (A)   Geyer, Brian C (A)   Fletcher, Samuel P (A)   Mor, Tsafrir S (A)
Affiliations:	(A): Arizona State University

Many signal transduction pathways have been evolutionarily conserved. While the pathways have acquired different roles in different organisms, much of their biochemistry has been conserved. Acetylcholine (ACh) is one of the most important signaling molecules in multicellular animals serving as neurotransmitter in the cholinergic synapse of the central nervous system and neuro-muscular junctions. It is efficiently removed from the synaptic cleft by acetylcholinesterase (AChE). Although the presence of ACh and AChE in plants has been known for years, the literature describing their function is incomplete. Here we report on the characterization of AChE activity in enriched preparations from pea roots. Like its mammalian counterpart, the enzyme can hydrolyse ACh better than it hydrolyses the longer-chain butrylcholine. The enzyme is sensitive to the carbamate AChE inhibitor nesostigmine bromide as well as to the organophosphate paraoxon. Yet unlike the mammalian enzyme, it is much less sensitive to the mammalian AChE inhibitor 1,5-bis allyldimethylammoniumphenyl pentan-3-one (BW284c51) and to inhibition by high concentration of substrate. Also reported are the consequences of selective inhibition of the plant’s endogenous AChE as well as ectopic expression of recombinant human AChE in transgenic plants.