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Acta Prataculturae Sinica ›› 2010, Vol. 19 ›› Issue (6): 147-153.

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Molecular cloning and sequencing of cDNAs of the novel protein Ho-Peritrophin3 from the peritrophic matrix of Holotrichia oblita, a turfgrass pest

ZHOU Hong-xu, LI Chang-you, LI Guo-xun   

  1. A Center for Advanced Invertebrate Cell Culture and Cell Engineering, Qingdao
    Agricultural University, Qingdao 266109, China
  • Received:2010-01-06 Online:2010-06-25 Published:2010-12-20

Abstract: Holotrichia oblita is an important turfgrass pest, whose peritrophic matrix is a potential target for biocontrol of pest insects. The peritrophic matrix proteins of H. oblita were studied by screening with a PM protein polyclonal antiserum from Helicoverpa armigera. One positive cDNA clone named Ho-Peritrophin3, with a size of 1 737 bp and a polyadenylation signal of AATAAA upstream of the polyA tail, was screened and sequenced from the library. The longest open reading frame of Ho-Peritrophin3 coded for 528 amino acids, which were mostly similar to Ho-Peritrophin2 of H. oblita, with a similarity of 64.9%. Ho-Peritrophin3, with a little O-linked glycosylation sites, contained five chitin binding domains, all of which consisted of six conserved cysteine residues, while Ho-Peritrophin1 and Ho-Peritrophin2 found in the PM of H. oblita contained only four cysteine residues at the C-terminal. No mucin-like domain was found in the Ho-Peritrophin3 sequence. The cleavage sites of trypsin and chymotrypsin mainly lay inside of CBDs in the Ho-Peritrophin3, and were protected by the intradomain disulfide bonds, so they can resist enzymes and exert a physiological function in the midgut. Compared with Ho-Peritrophin1 and Ho-Peritrophin2, 36.3% of 107 amino acids downstream of the fifth CBD belonged to the cleavage sites of trypsin and chymotrypsin. Further study is necessary to explain why Ho-Peritrophin3 can exist in the midgut in the presence of abundant proteinase.

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