title: Characterization of the AP endonucleases from Thermoplasma volcanium and Lactobacillus plantarum: Contributions of two important tryptophan residues to AP site recognition.
abstract: Escherichia coli AP endonuclease (ExoIII) and its human homolog (APE1) have the sole tryptophan residue for AP site recognition (AP site recognizer) but these residues are at different positions near the catalytic sites. On the other hand, many bacterial AP endonucleases have two tryptophan residues at the same positions of both ExoIII and APE1. To elucidate whether these residues are involved in AP site recognition, the ExoIII homologs of Thermoplasma volcanium and Lactobacillus plantarum were characterized. These proteins showed AP endonuclease and 3'-5'exonculease activities. In each enzyme, the mutations of the tryptophan residues corresponding to Trp-280 of APE1 caused more significant reductions in activities and binding abilities to the oligonucleotide containing an AP site (AP-DNA) than those corresponding to Trp-212 of ExoIII. These results suggest that the tryptophan residue corresponding to Trp-280 of APE1 is the predominant AP site recognizer, and that corresponding to Trp-212 of ExoIII is the auxiliary recognizer.
authors.affiliation: Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, Japan.
authors.forename: Kohichi
authors.initials: K
authors.lastname: Kaneda
authors.forename: Kaori
authors.initials: K
authors.lastname: Ohishi
authors.forename: Junichi
authors.initials: J
authors.lastname: Sekiguchi
authors.forename: Toshio
authors.initials: T
authors.lastname: Shida
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000502:physiology; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D048191:Lactiplantibacillus plantarum / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D013822:Thermoplasma / Q000201:enzymology* / Q000235:genetics; D014364:Tryptophan / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D050505:Mutant Proteins; D014364:Tryptophan; D004247:DNA; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase