Identification of four small molecular mass proteins in the silk of Bombyxmori

Citation
X. Nirmala et al., Identification of four small molecular mass proteins in the silk of Bombyxmori, INSEC MOL B, 10(5), 2001, pp. 437-445
Citations number
29
Categorie Soggetti
Entomology/Pest Control","Molecular Biology & Genetics
Journal title
INSECT MOLECULAR BIOLOGY
ISSN journal
09621075 → ACNP
Volume
10
Issue
5
Year of publication
2001
Pages
437 - 445
Database
ISI
SICI code
0962-1075(200110)10:5<437:IOFSMM>2.0.ZU;2-J
Abstract
This paper describes cDNAs of four small-size proteins that occur in the co coon silk of Bombyx mori. Two of them (9.9 and 10.3 kDa), which have the N- terminal sequences and the spacing of a few amino acids at C-termini simila r to the seroin of Galleria mellonella, are called seroin 1 and seroin 2. T he corresponding genes are expressed in the middle, and to a small extent a lso in the posterior silk gland sections. The seroin I and less conspicuous ly the seroin 2 mRNAs accumulate in the course of the last larval instar to a maximum in postspinning larvae. Two other proteins (6 kDa and 4.7 kDa) o f B. mori cocoons were identified as a typical Kunitz-type and a somewhat u nusual Kazal-type proteinase inhibitors, and named BmSPI 1 and BmSPI 2, res pectively. Their genes are expressed in the middle, and the BmSPI 1 gene sl ightly also in the posterior silk gland sections. The expression ensues a f ew days after the last larval ecdysis and increases until the cocoon spinni ng. Post-spinning larvae still contain high amounts of the BmSPI 1 but no B mSPI 2 transcripts. It is assumed that seroins and proteinase inhibitors ar e involved in cocoon protection against predators and microbes.