Heliothis virescens chymotrypsin is translationally controlled by AeaTMOF binding ABC putative receptor

Abstract

Heliothis virescens larval chymotrypsin (GenBank accession number AF43709) was cloned, sequenced and its three dimensional (3D) conformation modeled. The enzyme's transcript was first detected 6 days after larval emergence and the transcript level was shown to fall between larval ecdysis periods. Comparisons between the activities of larval gut chymotrypsin and trypsin shows that chymotrypsin activity is only 16% of the total trypsin activity and the pH optimum of the larval chymotrypsin is between pH 9−10, however the enzyme also exhibited a broad activity between pH 4−6. Injections of AeaTMOF and several shorter analogues into 3rd instar larvae followed by Northern blot analyses showed that although the chymotrypsins activities were inhibited by 60%−80% the transcript level of the sequenced chymotrypsin was not reduced and was similar to controls in which the chymotrypsin activity was not inhibited, indicating that AeaTMOF and its analogues exert a translational control. Based on these observations a putative AeaTMOF receptor (ABCC4) homologous to the Ae. aegypti ABC receptor sequence was found in the H. virescens genome. 3D molecular modeling and docking of the AeaTMOF and several of its analogues to the ABCC4 receptor showed that it can bind AeaTMOF and its analogues as was shown before for the Ae. aegypti receptor.

New Paralogs of the Heliothis virescens ABCC2 Transporter as Potential Receptors for Bt Cry1A Proteins

“…It is worth to note that these ECLs are involved in blocking the access of allocrites through the channel in the closed state [31]. Interestingly, it was recently described how the H. virescens ABCC4 characterized in this study shows homology to an ABC transporter previously described in mosquitoes [32]. This ABC transporter, known as AeaTMOF receptor, acts as an importer of a hormone involved in digestion control in the midgut of mosquitoes [6], and it was suggested to play a similar role in H. virescens [32].…”

“…It is worth to note that these ECLs are in in blocking the access of allocrites through the channel in the closed state [31]. In ingly, it was recently described how the H. virescens ABCC4 characterized in this shows homology to an ABC transporter previously described in mosquitoes [32 ABC transporter, known as AeaTMOF receptor, acts as an importer of a hormone in in digestion control in the midgut of mosquitoes [6], and it was suggested to play a role in H. virescens [32]. Therefore, it is worthwhile to elucidate the role of ABC tran ers in insects, as they may have a dual role in the response mechanisms to Bt, either as putative receptors or being involved in the processing response of Bt proteins gut digestion.…”