Differential activation of recombinant human acetyl-CoA carboxylases 1 and 2 by citrate

详细信息    查看全文

• 作者：Gregory A. Locke ; Dong Cheng ; Mark R. Witmer ; James K. Tamura ; Tasir Haque ; Robert F. Carney ; Alan R. Rendina ; Jovita Marcinkeviciene
• 关键词：Acetyl-CoA carboxylase ; Differential regulation ; Citrate ; Avidin inactivation ; Aggregation by DLS ; Half-site reactivity ; Phosphorylation ; LC/MS
• 刊名：Archives of Biochemistry and Biophysics
• 出版年：2008
• 出版时间：1 July 2008
• 年：2008
• 卷：475
• 期：1
• 页码：72-79
• 全文大小：613 K

文摘

The role of citrate as a physiological modulator of mammalian acetyl-CoA carboxylases (ACCs) has been well studied; however, the mechanism has not been clearly defined. In the current study, we found that citrate activated recombinant human ACC2 by more than 1000-fold, but activated recombinant human ACC1 only by 4-fold. The data fit best to a model which accounts for cooperative binding of two citrate molecules. Citrate activates ACCs at lower concentrations and inhibits at higher concentrations with apparent K_d values of 0.8 ± 0.3 and 3.4 ± 0.6 mM, and apparent K_i values of 20 ± 8 and 38 ± 8 mM for ACC1 and ACC2, respectively. In the absence of added citrate, both ACC1 and ACC2 were inactivated by avidin rapidly and completely. Addition of 10 mM citrate protected ACC2 from avidin inactivation; however, protection by citrate was less pronounced for ACC1. In response to citrate treatment, different aggregation patterns for the two isoforms were also observed by dynamic light scattering. Although formation of aggregates by both isoforms was sensitive to citrate, with Mg²⁺ and Mg-citrate addition only formation of the ACC2 aggregates showed a dependence on citrate concentration.