The Enzyme and the cDNA Sequence of a Thermolabile and Double-Strand Specific DNase from Northern Shrimps (Pandalus borealis)

• Published in: PLoS ONE
• Main Authors: Nilsen, Inge W., Lanes, Olav
• Other Authors: Lalueza-Fox, Carles
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2010
• Subjects: Kamchatka; Kamchatka crab; northern shrimp; Pandalus borealis
• Online Access: http://hdl.handle.net/10261/44040; https://doi.org/10.1371/journal.pone.0010295

Inge W. Nilsen et al. Background We have previously isolated a thermolabile nuclease specific for double-stranded DNA from industrial processing water of Northern shrimps (Pandalus borealis) and developed an application of the enzyme in removal of contaminating DNA in PCR-related technologies. Methodology/Principal Findings A 43 kDa nuclease with a high specific activity of hydrolysing linear as well as circular forms of DNA was purified from hepatopancreas of Northern shrimp (Pandalus borealis). The enzyme displayed a substrate preference that was shifted from exclusively double-stranded DNA in the presence of magnesium to also encompass significant activity against single-stranded DNA when calcium was added. No activity against RNA was detected. Although originating from a cold-environment animal, the shrimp DNase has only minor low-temperature activity. Still, the enzyme was irreversibly inactivated by moderate heating with a half-life of 1 min at 65°C. The purified protein was partly sequenced and derived oligonucleotides were used to prime amplification of the encoding cDNA. This cDNA sequence revealed an open reading frame encoding a 404 amino acid protein containing a signal peptide. By sequence similarity the enzyme is predicted to belong to a family of DNA/RNA non-specific nucleases even though this shrimp DNase lacks RNase activity and is highly double-strand specific in some respects. These features are in agreement with those previously established for endonucleases classified as similar to the Kamchatka crab duplex-specific nuclease (Par_DSN). Sequence comparisons and phylogenetic analyses confirmed that the Northern shrimp nuclease resembles the Par_DSN-like nucleases and displays a more distant relationship to the Serratia family of nucleases. Conclusions/Significance The shrimp nuclease contains enzyme activity that may be controlled by temperature or buffer compositions. The double-stranded DNA specificity, as well as the thermolabile feature, strengthens its potential for in vitro ...