Title

Molecular evolution of the cecropin multigene family in silkworm Bombyx mori

Authors

Kangayam M Ponnuvel*, Natarajan Subhasri, Sasibhushan Sirigineedi, Geetha N Murthy, Nanjappa B Vijayaprakash

Affiliation

Seribiotech Research Laboratory, Carmelaram– Post, Sarjapura Road, Kodathi, Bangalore- 560 035, INDIA;

E-mail*

kmpvel@gmail.com; * Corresponding author

Article Type

Hypothesis

Date

Received July 26, 2010; Accepted August 26, 2010; Published September 20, 2010

Cecropins constitute one of the largest and most potent immune protein families found in insect species with diversified numbers and features. In view of the large number of cecropin proteins existing with much sequence variations among them, an overview of the multigene cecropin family in silkworm Bombyx mori was attempted in this study. Cecropin encodes an inducible 64 residue anti-bacterial peptide and was clustered into two groups; first group viz. A and second group including B, D, E and Enbocin. Cecropin A consisted of two sub-groups located on chromosome number 6 of B.mori genome. Cecropin B consisted of six sub-groups, cecropin D and E of one each and Enbocin of two. The second sub-group formed in tandem array of multigene family locus over a length of 78.62 kb on chromosome number 26 in B.mori genome and was organized in positive as well as opposite orientation. The results indicated that cecropin B genes were organized in a close cluster with the intergenic sequence ranging from 1366 bp to 23526 bp. Interestingly a distantly related cecropin E was also located within the cecropin B multigene locus. Similarly distant members like cecropin D and Enbocin were also located in the 3’ region of cecropin B locus. The maximum intergenic region of 23526 bp observed between Cecropin D and Enbocin indicates that the two genes were distantly evolved. The phylogenetic analysis clearly indicates a positive correlation between the clusters and physical location on the chromosome, as the length of the intergenic region plays a major role to create newer cecropin families. EST database analysis suggests that most of the cecropin A members were expressed in the microbial fat body while, the cecropin B was equally expressed in fat body and other target tissues. The signal peptides were conserved in all the twelve paralogous gene sequences.

Keywords

Bombyx mori, cecropin, genomic organization, multigene, evolution.

Citation

Ponnuvel et al. Bioinformation 5(3): 97-103 (2010)

Edited by

P. Kangueane

ISSN

0973-2063

Publisher

License