A tetrameric acetylcholinesterase from the parasitic nematode Dictyocaulus viviparus associates with the vertebrate tail proteins PRiMA and ColQ.
Dictyocaulus viviparus causes a serious lung disease of cattle. Similar to other parasitic nematodes, D. viviparus possesses several acetylcholinesterase (AChE) genes, one of which encodes a putative neuromuscular AChE, which contains a tryptophan (W) amphiphilic tetramerization (WAT) domain at its C-terminus. In the current study, we describe the biochemical characterization of a recombinant version of this WAT domain-containing AChE. To assess if the WAT domain is biologically functional, we investigated the association of the recombinant enzyme with the vertebrate tail proteins, proline-rich membrane anchor (PRiMA) and collagen Q (ColQ), as well as the synthetic polypeptide poly-l-proline. The results indicate that the recombinant enzyme hydrolyzes acetylthiocholine preferentially and exhibits inhibition by excess substrate, a characteristic of AChEs but not butyrylcholinesterases (BChEs). The enzyme is inhibited by the AChE inhibitor, BW284c51, but not by the BChE inhibitors, ethopropazine or iso-OMPA. The enzyme is able to assemble into monomeric (G(1)), dimeric (G(2)), and tetrameric (G(4)) globular forms and can also associate with PRiMA and ColQ, which contain proline-rich attachment domains (PRADs). This interaction is likely to be mediated via WAT-PRAD interactions, as the enzyme also assembles into tetramers with the synthetic polypeptide poly-l-proline. These interactions are typical of AChE(T) subunits. This is the first demonstration of an AChE(T) from a parasitic nematode that can assemble into heterologous forms with vertebrate proteins that anchor the enzyme in cholinergic synapses. We discuss the implications of our results for this particular host/parasite system and for the evolution of AChE.
Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA. lpezzeme@bsc.edu
Leo
L
Pezzementi
Eric
E
Krejci
Arnaud
A
Chatonnet
Murray E
ME
Selkirk
Jacqueline B
JB
Matthews
D000110:Acetylcholinesterase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003094:Collagen / Q000378:metabolism*; D004021:Dictyocaulus / Q000201:enzymology*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D010802:Phylogeny; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D009419:Nerve Tissue Proteins; D010455:Peptides; D011994:Recombinant Proteins; C011083:polyproline; D003094:Collagen; D000110:Acetylcholinesterase