title: Potential double-flipping mechanism by E. coli MutY.
abstract: To understand the structural basis of the recognition and removal of specific mismatched bases in double-stranded DNAs by the DNA repair glycosylase MutY, a series of structural and functional analyses have been conducted. MutY is a 39-kDa enzyme from Escherichia coli, which to date has been refractory to structural determination in its native, intact conformation. However, following limited proteolytic digestion, it was revealed that the MutY protein is composed of two modules, a 26-kDa domain that retains essential catalytic function (designated p26MutY) and a 13-kDa domain that is implicated in substrate specificity and catalytic efficiency. Several structures of the 26-kDa domain have been solved by X-ray crystallographic methods to a resolution of up to 1.2 A. The structure of a catalytically incompetent mutant of p26MutY complexed with an adenine in the substrate-binding pocket allowed us to propose a catalytic mechanism for MutY. Since reporting the structure of p26MutY, significant progress has been made in solving the solution structure of the noncatalytic C-terminal 13-kDa domain of MutY by NMR spectroscopy. The topology and secondary structure of this domain are very similar to that of MutT, a pyrophosphohydrolase. Molecular modeling techniques employed to integrate the two domains of MutY with DNA suggest that MutY can wrap around the DNA and initiate catalysis by potentially flipping adenine and 8-oxoguanine out of the DNA helix.
authors.affiliation: Center for Molecular Science, University of Texas Medical Branch, Galveston, Texas 77555-1071, USA.
authors.forename: P G
authors.initials: PG
authors.lastname: House
authors.forename: D E
authors.initials: DE
authors.lastname: Volk
authors.forename: V
authors.initials: V
authors.lastname: Thiviyanathan
authors.forename: R C
authors.initials: RC
authors.lastname: Manuel
authors.forename: B A
authors.initials: BA
authors.lastname: Luxon
authors.forename: D G
authors.initials: DG
authors.lastname: Gorenstein
authors.forename: R S
authors.initials: RS
authors.lastname: Lloyd
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D020137:Base Pair Mismatch; D019757:Carbon-Oxygen Lyases / Q000737:chemistry / Q000502:physiology; D002384:Catalysis; D020134:Catalytic Domain; D004249:DNA Damage; D045647:DNA Glycosylases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000737:chemistry / Q000502:physiology*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011755:Pyrophosphatases; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C002992:8-hydroxyadenine; C024829:8-hydroxyguanine; D006147:Guanine; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D010744:Phosphoric Monoester Hydrolases; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D011755:Pyrophosphatases; C052211:mutT protein, E coli; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D000225:Adenine