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A serine protease in the midgut of the silkworm, Bombyx mori: protein sequencing, identification of cDNA, demonstration of its synthesis as zymogen form and activation during midgut remodeling.
Insect Biochem Mol Biol. 2009 Mar; 39(3):207-17.IB

Abstract

We identified a serine protease with a molecular mass of 37kDa in the midgut of the silkworm, Bombyx mori. The activity of this protease (37-kDa protease: p37k) appears after pupation, when the metamorphic remodeling of the midgut is under progress. The sequence analysis of the purified protease and its cDNA revealed that p37k is a trypsin-type serine protease, which is highly similar to serine proteases of other insects, including CG4386 of Drosophila melanogaster. In our molecular phylogenetic analysis, these proteases are grouped together with CG4386-like serine proteases of other insects to form an isolated cluster. The p37k protein and its putative orthologs present in this cluster have two unique sequence motifs, CxxCxC and FIDWLxxLLG, in the N-terminal side of the catalytic region. The gene for p37k is expressed in the midgut on day 2 of the silk-spinning larva, and the p37k polypeptide becomes detectable with a specific antibody at this stage of the midgut. On the other hand, p37k activity is not detectable until pupation, indicating that p37k is present in the larval midgut as an inactive precursor, which then is activated after pupation. A recombinant p37k produced using a baculovirus system is also inactive in its intact form. However, the recombinant p37k can be converted to an active protease when incubated in the homogenate of the midgut, suggesting that some unidentified midgut factor(s) are involved in the activation of p37k.

Authors+Show Affiliations

Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19114104

Citation

Kaji, Kentaro, et al. "A Serine Protease in the Midgut of the Silkworm, Bombyx Mori: Protein Sequencing, Identification of cDNA, Demonstration of Its Synthesis as Zymogen Form and Activation During Midgut Remodeling." Insect Biochemistry and Molecular Biology, vol. 39, no. 3, 2009, pp. 207-17.
Kaji K, Tomino S, Asano T. A serine protease in the midgut of the silkworm, Bombyx mori: protein sequencing, identification of cDNA, demonstration of its synthesis as zymogen form and activation during midgut remodeling. Insect Biochem Mol Biol. 2009;39(3):207-17.
Kaji, K., Tomino, S., & Asano, T. (2009). A serine protease in the midgut of the silkworm, Bombyx mori: protein sequencing, identification of cDNA, demonstration of its synthesis as zymogen form and activation during midgut remodeling. Insect Biochemistry and Molecular Biology, 39(3), 207-17. https://doi.org/10.1016/j.ibmb.2008.12.001
Kaji K, Tomino S, Asano T. A Serine Protease in the Midgut of the Silkworm, Bombyx Mori: Protein Sequencing, Identification of cDNA, Demonstration of Its Synthesis as Zymogen Form and Activation During Midgut Remodeling. Insect Biochem Mol Biol. 2009;39(3):207-17. PubMed PMID: 19114104.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A serine protease in the midgut of the silkworm, Bombyx mori: protein sequencing, identification of cDNA, demonstration of its synthesis as zymogen form and activation during midgut remodeling. AU - Kaji,Kentaro, AU - Tomino,Shiro, AU - Asano,Tsunaki, Y1 - 2008/12/16/ PY - 2008/04/19/received PY - 2008/11/13/revised PY - 2008/12/02/accepted PY - 2008/12/31/entrez PY - 2008/12/31/pubmed PY - 2009/4/2/medline SP - 207 EP - 17 JF - Insect biochemistry and molecular biology JO - Insect Biochem. Mol. Biol. VL - 39 IS - 3 N2 - We identified a serine protease with a molecular mass of 37kDa in the midgut of the silkworm, Bombyx mori. The activity of this protease (37-kDa protease: p37k) appears after pupation, when the metamorphic remodeling of the midgut is under progress. The sequence analysis of the purified protease and its cDNA revealed that p37k is a trypsin-type serine protease, which is highly similar to serine proteases of other insects, including CG4386 of Drosophila melanogaster. In our molecular phylogenetic analysis, these proteases are grouped together with CG4386-like serine proteases of other insects to form an isolated cluster. The p37k protein and its putative orthologs present in this cluster have two unique sequence motifs, CxxCxC and FIDWLxxLLG, in the N-terminal side of the catalytic region. The gene for p37k is expressed in the midgut on day 2 of the silk-spinning larva, and the p37k polypeptide becomes detectable with a specific antibody at this stage of the midgut. On the other hand, p37k activity is not detectable until pupation, indicating that p37k is present in the larval midgut as an inactive precursor, which then is activated after pupation. A recombinant p37k produced using a baculovirus system is also inactive in its intact form. However, the recombinant p37k can be converted to an active protease when incubated in the homogenate of the midgut, suggesting that some unidentified midgut factor(s) are involved in the activation of p37k. SN - 1879-0240 UR - https://www.unboundmedicine.com/medline/citation/19114104/A_serine_protease_in_the_midgut_of_the_silkworm_Bombyx_mori:_protein_sequencing_identification_of_cDNA_demonstration_of_its_synthesis_as_zymogen_form_and_activation_during_midgut_remodeling_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0965-1748(08)00210-5 DB - PRIME DP - Unbound Medicine ER -