Genome-Wide Identification and Characterization of Carboxypeptidase Genes in Silkworm (Bombyx mori).

Junhong Ye,Zhaoming Dong,Qingyou Xia,Jifu Li,Ping Zhao,Yi Li,Hua-Wei Liu

doi:10.3390/ijms17081203

Junhong Ye, Zhaoming Dong + Show 5 more

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https://doi.org/10.3390/ijms17081203

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Abstract

The silkworm (Bombyx mori) is an economically-important insect that can secrete silk. Carboxypeptidases have been found in various metazoan species and play important roles in physiological and biochemical reactions. Here, we analyzed the silkworm genome database and characterized 48 carboxypeptidases, including 34 metal carboxypeptidases (BmMCP1–BmMCP34) and 14 serine carboxypeptidases (BmSCP1–BmSCP14), to better understand their diverse functions. Compared to other insects, our results indicated that carboxypeptidases from silkworm have more family members. These silkworm carboxypeptidases could be divided into four families: Peptidase_M2 carboxypeptidases, Peptidase_M14 carboxypeptidases, Peptidase_S10 carboxypeptidases and Peptidase_S28 carboxypeptidases. Microarray analysis showed that the carboxypeptidases had distinct expression patterns, whereas quantitative real-time PCR demonstrated that the expression level of 13 carboxypeptidases significantly decreased after starvation and restored after re-feeding. Overall, our study provides new insights into the functional and evolutionary features of silkworm carboxypeptidases.

Highlights

In insects, food proteins are preliminary digested by midgut endopeptidases and by exopeptidases into single free amino acids that are further absorbed by intestinal cells [1]
Carboxypeptidases are classified into two sub-categories, according to their catalytic mechanism: serine carboxypeptidases with an active serine residue in the active site and metal carboxypeptidases with a metal ion in the active site [3,4]
Carboxypeptidases have been identified in many insects, including Simulium vittatum [8], Glossina morsitans [9], Helicoverpa armigera [10], Mamestra configurata [11], Anopheles gambiae [12], Aedes aegypti [13], Trichoplusia ni [1,14] and Triatoma brasiliensis [15]

Summary

Introduction

Food proteins are preliminary digested by midgut endopeptidases and by exopeptidases into single free amino acids that are further absorbed by intestinal cells [1]. Endopeptidases, such as trypsin, chymotrypsin, elastase, thermolysin, pepsin, glutamyl endopeptidase, cathepsin B, cathepsin L and neprilysin, are proteolytic peptidases that break the peptide bonds of nonterminal amino acids. In 1997, Broadway identified five types of carboxypeptidases in the midgut of Trichoplusia ni [14] and reported that carboxypeptidase A is eight-fold more active than carboxypeptidase B [1]. In blood-sucking insect populations, the expression of digestive carboxypeptidase genes is promoted by blood meal [8,12]

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