C. Leboulay et al., CLONING AND EXPRESSION OF CATHEPSIN L-LIKE PROTEINASES IN THE HEPATOPANCREAS OF THE SHRIMP PENAEUS-VANNAMEI DURING THE INTERMOLT CYCLE, Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, 166(5), 1996, pp. 310-318
Cysteine protease activities have been characterized with benzyloxycar
bonyl-lysine p-nitrophenyl ester as a synthetic substrate and E64 as a
specific inhibitor in the hepatopancreas of the shrimp Penaeus vannam
ei. An optimum pH of 5.1 has been measured. To characterize these cyst
eine proteases, a hepatopancreas cDNA library was screened by hybridiz
ation to a Norway lobster cysteine protease cDNA fragment. Two cDNAs e
ncoding P. vannamei cysteine protease precursors have been cloned and
sequenced. The encoded polypeptides have 326 and 322 amino acid residu
es, respectively, each consisting of partial signal sequences (15 and
10 residues), a pro-region (93 and 94 residues), and a mature enzyme p
olypeptide (218 residues). Cys(25), His(159) and Asn(175) form the cat
alytic triad in the putative active site of the mature enzymes. Compar
ed with invertebrate cysteine proteases (Homarus and Fasciola), each o
f the two shrimp enzymes shows 70 and 52% amino acid sequence identity
, respectively; 63% identity is shown with rat cathepsin L. Northern h
ybridization analysis showed the same size for the different cysteine
protease transcripts in hepatopancreas tissue (approximately 1.1 kb).
During intermolt cycles, variations in cysteine protease activity were
correlated with the variations in the levels of specific mRNA.