Abstract: Acetyl-CoA carboxylase(ACC) is the key enzyme in fatty acid metabolism that catalyzes the irreversible carboxylation of acetyl-CoA to produce malonyl-CoA through its two catalytic activities, biotin carboxylase(BC) and carboxyltransferase(CT). CT domain has been recognized as the critical target site of herbicide. If the soluble CT protein could be obtained, it would be beneficial for us to investigate the recognition mechanism of ACCase, further to design and develop novel herbicides. In this work, the ACCase CT domain from wheat was cloned and over expressed in E. coli in a soluble form; however the expressed protein exhibited higher hydrophobility and lower stability. In order to improve the situation, different lengths of CT genes was cloned and expressed in E. coli. The results showed that only 2325 bp gene could be expressed in a soluble form, which selected as the material to carry on the subsequent investigation; the 2109 bp gene was expressed in inclusion body state, while the 1869 bp and the 3501 bp gene could not be expressed in E. coli. The interactions of the soluble recombinant CT domain with herbicide were investigated by circular dichroism spectra(CD) and differential scanning calorimeter(DSC). The CD results showed that the spectra of CT protein were changed obviously in the presence of herbicide, indicating there was a strong interaction between the CT domain and herbicide. The DSC assay indicated that the thermal stability of recombinant CT protein was increased in the presence of herbicide. These results will provide important references for rational designing novel herbicide.

Key words: Acetyl\, CoA carboxylase, Carboxyltransferase domain, Protein expression, Interaction, Herbicide