N. Tsuji et al., Identification of an asparagine amidohydrolase from the filarial parasite Dirofilaria immitis, INT J PARAS, 29(9), 1999, pp. 1451-1455
The nematode cuticle is a complex extracellular structure which is secreted
by an underlying syncytium of hypodermal cells. Recent studies have demons
trated that the cuticle of parasitic nematodes is a dynamic structure with
important absorptive, secretory, and enzymatic activities. In addition, the
cuticle serves as a protective barrier against the host. A 48-h third stag
e larval Dirofilaria immitis cDNA library was immunoscreened with sera rais
ed against larval cuticles. One clone, L3MC4 that reacted strongly with the
anti-cuticle antisera was sequenced. The composite cDNA sequence comprises
2073 bp coding for a full-length protein of 590 amino acids. GenBank analy
sis showed that DiAsp had significant similarity to a Caenorhabditis elegan
s gene-product (54% identity) and to other asparaginases at the amino acid
level. Escherichia coli-expressed recombinant DiAsp (rDiAsp) catalysed the
hydrolysis of asparagine to aspartate and ammonia. Antibodies raised agains
t D. immitis larval cuticles reacted with rDiAsp in immunoblots. This is th
e first report of identification of a cDNA clone encoding an asparaginase e
nzyme from a parasitic nematode. (C) 1999 Australian Society for Parasitolo
gy Inc. Published by Elsevier Science Ltd. All rights reserved.