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Identification and molecular characterization of a chitin deacetylase from Bombyx mori peritrophic membrane
Xiao-Wu Zhong1, Xiao-Huan Wang2, Xiang Tan3
1State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China. zxw_strive@163.com.
Abstract:
The insect midgut epithelium is generally lined with a unique chitin and protein structure, the peritrophic membrane (PM), which facilitates food digestion and protects the gut epithelium. PM proteins are important determinants for PM structure and formation. In this study, the silkworm Bombyx mori midgut PM protein BmCDA7 was identified by proteomic tools. The full-length BmCDA7 cDNA is 1357 bp; the deduced protein is composed of 379 amino acid residues and includes a 16 amino acid residue signal peptide, a putative polysaccharide deacetylase-like domain and 15 cysteine residues present in three clusters. The heterologously expressed proteins of the BmCDA7 gene in yeast displayed chitin deacetylase activity. Expression of B. mori BmCDA7 was detected in the midgut at both the transcriptional and translational levels. The BmCDA7 gene was expressed by the newly hatched silkworm larvae until day seven of the fifth instar and was expressed at a high level in the newly exuviated larvae of different instars. The functions and regulatory mechanism of BmCDA7, however, need further investigation.
Insights
Researchers identified a novel silkworm peritrophic membrane (PM) protein, BmCDA7, with chitin deacetylase activity. This protein is crucial for insect gut structure and function, with expression varying across larval stages.
Area of Science:
- Entomology
- Biochemistry
- Molecular Biology
Background:
- The insect midgut epithelium is protected by a peritrophic membrane (PM), a chitin-protein layer vital for digestion and defense.
- Peritrophic membrane proteins are key to its structural integrity and formation.
Purpose of the Study:
- To identify and characterize a novel protein component of the silkworm Bombyx mori peritrophic membrane.
- To investigate the enzymatic activity and expression patterns of the identified protein, BmCDA7.
Main Methods:
- Proteomic analysis to identify PM proteins in Bombyx mori midgut.
- Gene cloning, heterologous expression in yeast, and enzymatic assays.
- Quantitative analysis of gene expression at transcriptional and translational levels across different larval stages.
Main Results:
- The silkworm peritrophic membrane protein BmCDA7 was identified, with its gene encoding a 379-amino acid protein containing a signal peptide and a polysaccharide deacetylase-like domain.
- Heterologous expression of BmCDA7 in yeast confirmed its chitin deacetylase activity.
- BmCDA7 expression was detected in the midgut throughout larval development, with peak expression in newly molted larvae.
Conclusions:
- BmCDA7 is a functional chitin deacetylase involved in peritrophic membrane formation in Bombyx mori.
- The expression patterns suggest a role for BmCDA7 in larval growth and molting processes.
- Further research is needed to elucidate the precise functions and regulatory mechanisms of BmCDA7.
