Structures of the Arm-type Binding Domains of HPI and HAI7 Integrases |
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| Authors: | Aleksandra Szwagierczak Uladzimir Antonenka Grzegorz M Popowicz Tomasz Sitar Tad A Holak and Alexander Rakin |
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| Institution: | From the ‡Max Planck Institute for Biochemistry, D-82152 Martinsried, Germany and ;the §Max von Pettenkofer Institute, Ludwig Maximilians University, D-80336 Munich, Germany |
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| Abstract: | The structures of the N-terminal domains of two integrases of closely related but not identical asn tDNA-associated genomic islands, Yersinia HPI (high pathogenicity island; encoding siderophore yersiniabactin biosynthesis and transport) and an Erwinia carotovora genomic island with yet unknown function, HAI7, have been resolved. Both integrases utilize a novel four-stranded β-sheet DNA-binding motif, in contrast to the known proteins that bind their DNA targets by means of three-stranded β-sheets. Moreover, the β-sheets in IntHPI and IntHAI7 are longer than those in other integrases, and the structured helical N terminus is positioned perpendicularly to the large C-terminal helix. These differences strongly support the proposal that the integrases of the genomic islands make up a distinct evolutionary branch of the site-specific recombinases that utilize a unique DNA-binding mechanism. |
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