1. Bioinformatics & Structural Biology M93360008 生技所 研一 劉怡萱 M93360008 生技所 研一 劉怡萱

2. Crystal Structure of PriB, a Component of the Escherichia coli Replication Restart Primosome Structure, Vol. 12, 1967–1975, November, 2004 Matthew Lopper, 1 James M. Holton, 2 and James L. Keck 1,* ( 1 Department of Biomolecular Chemistry University of Wisconsin Medical School 2 Physical Biosciences Division Lawrence Berkeley National Laboratory ) The PDB ID of PriB : 1TXY

3. PDB Code : 1txy Classification : DNA binding protein Exp. Method : X-ray Diffraction Structure : Primosomal replication protein N Chain : a, b. Engineered: yes Source : Escherichia coli. Bacteria. Gene: prib, b4201. Expressed in: escherichia coli. Resolution : 2.0 À R-factor : 0.260 (Statistical factor) R-free : 0.285 (Statistical factor) Authors : J.L.Keck,M.Lopper,J.M.Holton Date : 06-Jul-04 Polymer Chains : A, B Residues ;Atoms : 208,1515 The PDB Structure summary of PriB

4. Structural similarity Structural similarity of PriB to single-stranded DNA binding proteins reveals insights into its mechanisms of DNA binding. The structure further establishes a putative protein interaction surface that may contribute to the role of PriB in primosome assembly by facilitating interactions with PriA and DnaT. The structure further establishes a putative protein interaction surface that may contribute to the role of PriB in primosome assembly by facilitating interactions with PriA and DnaT. E. coli PriB, revealing a dimer that consists of a single structural domain formed by two oligonucleotide/oligosaccharide binding (OB) folds. E. coli PriB, revealing a dimer that consists of a single structural domain formed by two oligonucleotide/oligosaccharide binding (OB) folds. The analysis on the crystal structure of PriB This is the first high-resolution structure of any of the proteins involved in oriC-independent replisome loading and provides unique insight into a critical aspect of genome maintenance in E. coli.

5.  Briefly, the PriB monomer structure has two pleated β-sheets capped by a small α-helix located between the third and the fourth strands to form a β-barrel The core of the -barrel is filled with hydrophobic residues.

6.  The structure shows that PriB forms a homodimeric β- barrel with two oligonucleotide/oligosaccharide binding (OB) folds.

7.  The polypeptide chain of PriB is structurally similar to that of single-stranded DNA-binding protein (SSB). However, the biological unit of PriB is a dimer, not a homotetramer like SSB.

8.  Interestingly, of the eight lysine residues of the PriB dimer, only Lys82 is positionally conserved with a lysine residue of SSB involved in contacting nucleic acid, Lys87. Located at the base of the L45 loop, PriB Lys82 appears to be in a prime position to make contacts with ssDNA (Figure 4A).

9. Further Work  To understand the parameters of Structural Biology (ex: R-factor 、 R-free 、 Space Group )  To compare the paper “Crystal Structure of PriB, a Primosomal DNA Replication Protein of Escherichia coli*” in JBC 2004 with this paper ( §Institute of Molecular Biology, Academia Sinica)  To analyze the basic properties of PriB by Swiss-Pdb Viewer  To observe the crystal structure of the E. coli PriB homodimer by Swiss-Pdb Viewer  To compare the crystal structure of the E. coli PriB homodimer with the hetertetramer of SSB by Swiss-Pdb Viewer  Give some different ideas

10. The End Thank for your attention