Cloning and expression of 32 kDa ferritin from Galleria mellonella

We have sequenced a cDNA clone encoding 32-kDa ferritin subunit in the Wax Moth, Galleria mellonella. The 32-kDa ferritin subunit cDNA was obtained from PCR using identical primer designed from highly conserved regions of insect ferritins. RACE PCR was used to obtain the complete protein coding sequence. The 32-kDa ferritin subunit encoded a 232 amino acid polypeptide, containing a 19 leader peptide. The iron-responsive element (IRE) sequence with a predicted stem-loop structure was present in the 5'-untranslated region of the wax moth 32-kDa ferritin subunit mRNA. The 32-kDa sequence alignment had 78 and 69% identity with Manduca sexta and Calpodes ethlius (G), respectively. The G. mellonella ferritin subunits showed minimal identity with each other (19%). The glycosylation site (Asn-X-Ser/Thr) was found in the 32-kDa subunit but not in the 26-kDa subunit. Northern blot analysis showed that the mRNA expression of the 32-kDa ferritin was detected in the fat body and midgut. The fat body expression increased after 6 h and the mRNA in midgut dramatically increased about 3-fold the expression level at 12 h after iron feeding. Western blot revealed that a protein level of the 32-kDa subunit is abundant in midgut after 12 and 24 h iron feeding.