title: Active site sharing and subterminal hairpin recognition in a new class of DNA transposases.
abstract: Many bacteria harbor simple transposable elements termed insertion sequences (IS). In Helicobacter pylori, the chimeric IS605 family elements are particularly interesting due to their proximity to genes encoding gastric epithelial invasion factors. Protein sequences of IS605 transposases do not bear the hallmarks of other well-characterized transposases. We have solved the crystal structure of full-length transposase (TnpA) of a representative member, ISHp608. Structurally, TnpA does not resemble any characterized transposase; rather, it is related to rolling circle replication (RCR) proteins. Consistent with RCR, Mg2+ and a conserved tyrosine, Tyr127, are essential for DNA nicking and the formation of a covalent intermediate between TnpA and DNA. TnpA is dimeric, contains two shared active sites, and binds two DNA stem loops representing the conserved inverted repeats near each end of ISHp608. The cocrystal structure with stem-loop DNA illustrates how this family of transposases specifically recognizes and pairs ends, necessary steps during transposition.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ronning
authors.forename: Catherine
authors.initials: C
authors.lastname: Guynet
authors.forename: Bao
authors.initials: B
authors.lastname: Ton-Hoang
authors.forename: Zhanita N
authors.initials: ZN
authors.lastname: Perez
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ghirlando
authors.forename: Michael
authors.initials: M
authors.lastname: Chandler
authors.forename: Fred
authors.initials: F
authors.lastname: Dyda
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004251:DNA Transposable Elements / Q000502:physiology; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D016480:Helicobacter pylori / Q000201:enzymology* / Q000472:pathogenicity; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary; D012091:Repetitive Sequences, Nucleic Acid / Q000502:physiology; D019895:Transposases / Q000737:chemistry* / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D037521:Virulence Factors; D014443:Tyrosine; D019895:Transposases; D008274:Magnesium