Characterization of the functional role of zinc-finger motif in acetyle-CoA carboxylase

点击翻译按钮获取中文摘要

Acetyl-CoA carboxylase (ACCase) [EC 6.4.1.2] catalyzes the first committed step of fatty acid synthesis, namely the carboxylation of acetyl-CoA to form malonyl-CoA. Chloroplast ACCase is a multienzyme complex composed of biotin carboxylase and carboxyltransferase (CT), which is made up of α_2β_2 heterodimer. The CT β polypeptide has the conserved zinc forger-like domain (C-x_2-C-x_<(12-15)>-C-x_2-C) in the N-terminal region. We examined the role of this domain of pea chloroplast CT. The recombinant enzymes without this domain did not have the enzymatic activities. The measurements of metal contents by ruing the inductively coupled argon plasma spectrometer showed that this domain contains the zinc ions. Additionally, the zinc chelator 1,10-o-phenanthroline inhibited the enzymatic activities. These results indicate that the conserved zinc forger-like domain has the ability to bind the zinc ions, and that zinc-binding activity is required for the enzymatic activities.