1olo

Hexameric Replicative DNA Helicase RepA from Plasmid RSF1010 - Cubic Crystal Structure

spinqualitylabelsall models 1olo, resolution 2.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1olo is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.55Å Ligands: SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function REPJ_ECOLX This protein is involved in regulating the plasmid copy-number. Increasing the level of this protein results in a higher plasmid copy-number. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed In the known monoclinic crystals the 3-dimensional structure of the hexameric, replicative helicase RepA encoded by plasmid RSF1010 shows 6-fold rotational symmetry. In contrast, in the cubic crystal form at 2.55 A resolution described here RepA has 3-fold symmetry and consists of a trimer of dimers. To study structure-function relationships, a series of repA deletion mutants and mutations yielding single amino acid exchanges were constructed and the respective gene products were analyzed in vivo and in vitro. Hexamerization of RepA occurs via the N-terminus and is required for NTP hydrolysis. The C-terminus is essential both for the interaction with the replication machinery and for the helicase activity. Functional analyses of RepA variants with single amino acid exchanges confirmed most of the predictions that were based on the published 3-dimensional structure. Of the five motifs conserved in family 4 helicases, all residues conserved in RepA and T7 gp4 helicases participate in DNA unwinding. Residues K42, E76, D77, D139 and H178, proposed to play key roles in catalyzing the hydrolysis of NTPs, are essential for RepA activity. Residue H178 of motif H3 couples nucleotide consumption to DNA strand separation. Hexameric RSF1010 helicase RepA: the structural and functional importance of single amino acid residues.,Ziegelin G, Niedenzu T, Lurz R, Saenger W, Lanka E Nucleic Acids Res. 2003 Oct 15;31(20):5917-29. PMID:14530440 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Helicase 3D structures

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