Docstoc

Work in Progress - University of Georgia

Document Sample
Work in Progress - University of Georgia Powered By Docstoc
					Please note this presentation is part of an assignment for a
graduate course in Advanced Biochemistry and Molecular Biology
8010 at the University of Georgia. Questions should be directed
to Justin Polizzi, spolizzi@uga.edu . Images were created in
RasMol using PDB files 1qnf or 1buc, and manipulated in
Microsoft PowerPoint.


All referenced material is credited in the literature cited page of
the Enzyme Report PDF
DNA Photolyase




      Justin Polizzi
      BCMB 8010
  University of Georgia
                The Problem




Cyanobacteria

                    Photoproducts
        The Solution: DNA Photolyase
                                  •   Single Polypeptide
                                  •   2 Domains
α-helical domain                  •   Substrate Binding Site
                                  •   Photoantenna Binding Site
                                  •   Catalytic Cofactor Binding


                                  •   Binds Pyrimidine Dimer (TT)
                                  •   Antenna Photoactivated
                                  •   Catalytic Cofactor Activated
                                  •   Dimer Photoreactivated
                   α/β open sheet •   Release Original Monomers
        The Solution: DNA Photolyase
                                    α-Helical Domain
                                    • Substrate Binding Site
                 α-helical domain    AND
α/β open sheet                      • Catalytic Cofactor Binding
                                    • Redox Active (FAD)


                                    α/β Open Sheet
                                    • Photoantenna Binding
                                    • Class Determining
                                    • Folate (MTHF)
                                     OR
                                    • Deazaflavin (HDF)
                                    • Anacystis nidulans
                                             Substrate
                                             Binding



Looking into
active site

• Substrate
• Cis-syn cyclobutane
  pyrimidine dimer (CPD)
• TT in DNA
• Sequence independent         Looking
                               down from
• Electrostatic interactions   active site
              Ribityl Moiety   Photoantenna Cofactor
                               Binding


          Isoalloxazine Ring



• 8-hydroxy-5-deazaflavin
  (HDF)
• Cofactor Specificity
• Binding both HDF groups
• Multiple bond types
• Coordination via water
                              Catalytic
                              Cofactor
                              Binding
Adenine Moiety


                           • Flavin Adenine
                             Dinucleotide (FAD)
                           • Conserved Binding
                           • Normal I-Shape (Left)
                           • U-Shape (Right)
                             Unique to Photolyases


      Isoalloxazine Ring
Catalytic
Cofactor
Binding
    Structures and Mechanism

Photon input

                                    HDF




                                   Transfer excitation energy




                                                FAD

               Donate e-

                                 Return e-
                           CPD

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:4/19/2013
language:Unknown
pages:10