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Isolation and Characterization of Skin-type, Type I Antifreeze Polypeptides from the Longhorn Sculpin, Myoxocephalus octodecemspinosus

2001; Elsevier BV; Volume: 276; Issue: 15 Linguagem: Inglês

10.1074/jbc.m009293200

1083-351X

Woon‐Kai Low, Qingsong Lin, Costas Stathakis, Ming Miao, Garth L. Fletcher, Choy L. Hew,

Meat and Animal Product Quality

The antifreeze polypeptides (AFPs) are found in several marine fish and have been grouped into four distinct biochemical classes (type I-IV). Recently, the new subclass of skin-type, type I AFPs that are produced intracellularly as mature polypeptides have been identified in the winter flounder (Pleuronectes americanus) and the shorthorn sculpin (Myoxocephalus scorpius). This study demonstrates the presence of skin-type AFPs in the longhorn sculpin (Myoxocephalus octodecemspinosus), which produces type IV serum AFPs. Using polymerase chain reaction-based methods, a clone that encoded for a type I AFP was identified. The clone lacked a signal sequence, indicating that the mature polypeptide is produced in the cytosol. A recombinant protein was produced in Escherichia coli and antifreeze activity was characterized. Four individual Ala-rich polypeptides with antifreeze activity were isolated from the skin tissue. One polypeptide was completely sequenced by tandem MS. This study provides the first evidence of a fish species that produces two different biochemical classes of antifreeze proteins (type I and type IV), and enforces the notion that skin-type AFPs are a widespread biological phenomenon in fish.