[BK21 Plus Seminar]
     
       
    ▶Subject: Enzyme Regulatory Mechanism controlled by a membrane-binding amphipathic helix
           
    
    ▶Speaker: Jaeyong Lee, Ph.D.

                     (Molecular Biology and Biochemistry, Simon Fraser University)
             
    
    ▶Date: 3:00PM/Sep/17(Wed)/2014
            
      
    ▶Place: Life Science Bldg. #104
            
    
           *Abctract
         CTP:phosphocholine cytidylyltransferase (CCT) is the key regulatory enzyme in the synthesis of phosphatidylcholine (PC), the most abundant phospholipid in eukaryotic cell membranes. Point mutations in CCT are linked to human genetic disorders characterized by severely impaired skeletal growth and retinal dystrophy. It is also a prototype for a class of enzymes that are regulated by reversible membrane binding (amphitropism). How membrane binding activates catalytic function in these proteins is generally not well understood. 

CCT catalyzes the transfer of a cytidylyl group from CTP to phosphocholine to form CDP-choline and is regulated by a membrane lipid-dependent mechanism imparted by its C-terminal membrane binding domain (domain M). CCT binds selectively to membrane surfaces depleted of PC via an inducible amphipathic helix in the domain M.  This interaction increases the catalytic efficiency by ~500-fold, leading to restoration of PC content. When CCT is not membrane engaged, the domain M functions to silence the catalysis. 

Elucidation and analysis of the X-ray crystal structures of CCT mutant constructs provide surprisingly novel insights and reveal the molecular details of the regulatory mechanism imparted by the domain M.

    ▶Inquiry: Kim, Joung-Hun (279-2347)
           
     
     * This seminar will be given in English