6pcm | pdb_00006pcm

Crystal Structure of Mycobacterium smegmatis Topoisomerase I with ssDNA bound to both N- and C-terminal domains

spinqualitylabelsall models 6pcm, resolution 3.11Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6pcm is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO4 Activity: DNA topoisomerase, with EC number 5.6.2.2 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TOP1_MYCS2] Releases the supercoiling and torsional tension of DNA, which is introduced during the DNA replication and transcription, by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate (PubMed:9593741) and the expulsion of a 3'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand, thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone (By similarity).[HAMAP-Rule:MF_00952] Relaxes negatively (but not positively) supercoiled DNA, concatanates and knots circular ssDNA at 52 but not 37 degrees Celsius (PubMed:9593741). Preferentially nicks supercoiled DNA at C(G/T)CTT, cutting between the TT residues, binds ss and dsDNA with the recognition site (PubMed:10734203).

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