Full Length Research Paper

Cloning and characterization of peptidylprolyl isomerase B in the silkworm, Bombyx mori

Hengchuan Xia^1#, Honggang Lv^1# Keping Chen^1*, Qin Yao1, Peng Lv¹, Jun Li¹, Huiqing Chen¹ and Lin Wang²

¹Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, P. R. China.

²Beijing Entry-Exit Inspection and Quarantine Bureau, No. 6 Tianshuiyuan Street, Chaoyang District, Beijing 100026, P. R. China.

*Corresponding author. E-mail: kpchen@ujs.edu.cn. Tel: +86 511 88791923.

Fax: +86 511 88791923.

#These authors contributed equally to this paper

Abbreviations: PPIase, Peptidylprolyl isomerase; Cyps, cyclophilins; FKBPs, FK 506 binding proteins; B. mori, Bombyx mori; BmNPV, Bombyx mori nucleopolyhedrovirus.

Accepted 12 October, 2009

   Abstract

Peptidylprolyl isomerases (PPIases) play essential roles in protein folding and are implicated in immune response and cell cycle control. Our previous proteomic analysis indicated that Bombyx mori PPIases may be involved in anti- Bombyx mori nucleopolyhedrovirus (BmNPV) response. To help investigate this mechanism, we cloned a B. mori PPIase gene PPIB and characterized it by bioinformatic and experimental analysis. We found that the B. mori PPIB gene contains 4 exons and its cDNA is about of 618 bp, encoding a protein of 205 amino acid residues (21474.41 Da) with an isoelectric point of 8.05. PPIB contains conserved and unique cyclophilin domain and belongs to cyclophilin superfamily. Its transcription could be detected by PCR in all the B. mori tissue samples, which is consistent with normal PPIase expression pattern and their essential roles. It is localized in cytoplasm revealed by fluorescence microscopy. We also successfully expressed this protein in E. coli and characterized it by SDS-PAGE and Mass Spectrometry. The cloned DNA sequence was submitted to GenBank (EU583493).

Key words: Bioinformatics, transcription analysis, prokaryotic expression, mass spectrometry, subcellular localization.