A Novel Trypsin Inhibitor-Like Cysteine-Rich Peptide from the Frog Lepidobatrachus laevis Containing Proteinase-Inhibiting Activity.
Various bio-active substances in amphibian skins play important roles in survival of the amphibians. Many protease inhibitor peptides have been identified from amphibian skins, which are supposed to negatively modulate the activity of proteases to avoid premature degradation or release of skin peptides, or to inhibit extracellular proteases produced by invading bacteria. However, there is no information on the proteinase inhibitors from the frog Lepidobatrachus laevis which is unique in South America. In this work, a cDNA encoding a novel trypsin inhibitor-like (TIL) cysteine-rich peptide was identified from the skin cDNA library of L. laevis. The 240-bp coding region encodes an 80-amino acid residue precursor protein containing 10 half-cysteines. By sequence comparison and signal peptide prediction, the precursor was predicted to release a 55-amino acid mature peptide with amino acid sequence, IRCPKDKIYKFCGSPCPPSCKDLTPNCIAVCKKGCFCRDGTVDNNHGKCVKKENC. The mature peptide was named LL-TIL. LL-TIL shares significant domain similarity with the peptides from the TIL supper family. Antimicrobial and trypsin-inhibitory abilities of recombinant LL-TIL were tested. Recombinant LL-TIL showed no antimicrobial activity, while it had trypsin-inhibiting activity with a Ki of 16.5178 μM. These results suggested there was TIL peptide with proteinase-inhibiting activity in the skin of frog L. laevis. To the best of our knowledge, this is the first report of TIL peptide from frog skin.
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Yu-Wei
YW
Wang
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Ji-Min
JM
Tan
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Can-Wei
CW
Du
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Ning
N
Luan
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
Xiu-Wen
XW
Yan
Life Sciences College of Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.|Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, Yunnan, China.
Ren
R
Lai
Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, Yunnan, China. lvqm@aliyun.com.
Qiu-Min
QM
Lu
Amphibian; Cysteine-rich peptide; Skin; Trypsin inhibitor