Molecular cloning and characterization of High Mobility Group box (HMGB) gene from Beauveria bassiana- infected silkworm, Bombyx mori

The cDNA sequence of High Mobility Group box ( HMGB) from Bombyx mori was cloned by rapid amplification of cDNA ends and submitted to GenBank ( the accession number was JF969272). The full-length cDNA of BmHMGB included 3015 bp, with five exons and four introns. It contained a 313 bp 5' UTR, a 2114 bp 3' UTR with a polyadenylation signal sequence AATAAA and a poly( A) tail. It encodes a 195- amino acid polypeptide with a predicted molecular weight about 22991.9Da and a theoretical isoelectric point 10.00. Phylogenetic analysis revealed that BmHMGB is grouped in insect HMGB proteins. BmHMGB was mainly expressed in hemolymph, cuticles, midgut and fat body by RT-PCR. In these tissues, the relative expression of BmHMGB with Beauveria bassiana infected silkworm was higher than the normal ones by fluorescent quantitative real-time PCR. Therefore, BmHMGB may play an important function in the response to B. bassiana infection of silkworms.