This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1xo1
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1xo1.jpg|left|200px]] | [[Image:1xo1.jpg|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1xo1", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1xo1| PDB=1xo1 | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''T5 5'-EXONUCLEASE MUTANT K83A''' | '''T5 5'-EXONUCLEASE MUTANT K83A''' | ||
| Line 24: | Line 21: | ||
Mutagenesis of conserved lysine residues in bacteriophage T5 5'-3' exonuclease suggests separate mechanisms of endo-and exonucleolytic cleavage., Garforth SJ, Ceska TA, Suck D, Sayers JR, Proc Natl Acad Sci U S A. 1999 Jan 5;96(1):38-43. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9874768 9874768] | Mutagenesis of conserved lysine residues in bacteriophage T5 5'-3' exonuclease suggests separate mechanisms of endo-and exonucleolytic cleavage., Garforth SJ, Ceska TA, Suck D, Sayers JR, Proc Natl Acad Sci U S A. 1999 Jan 5;96(1):38-43. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9874768 9874768] | ||
[[Category: Enterobacteria phage t5]] | [[Category: Enterobacteria phage t5]] | ||
| - | [[Category: Exodeoxyribonuclease (lambda-induced)]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Ceska, T A.]] | [[Category: Ceska, T A.]] | ||
[[Category: Sayers, J R.]] | [[Category: Sayers, J R.]] | ||
[[Category: Suck, D.]] | [[Category: Suck, D.]] | ||
| - | [[Category: | + | [[Category: Exonuclease]] |
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Nuclease]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:16:57 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 12:16, 3 May 2008
T5 5'-EXONUCLEASE MUTANT K83A
Overview
Efficient cellular DNA replication requires the activity of a 5'-3' exonuclease. These enzymes are able to hydrolyze DNA.DNA and RNA.DNA substrates exonucleolytically, and they are structure-specific endonucleases. The 5'-3' exonucleases are conserved in organisms as diverse as bacteriophage and mammals. Crystal structures of three representative enzymes identify two divalent-metal-binding sites typically separated by 8-10 A. Site-directed mutagenesis was used to investigate the roles of three lysine residues (K83, K196, and K215) situated near two metal-binding sites in bacteriophage T5 5'-3' exonuclease. Neither K196 nor K215 was essential for either the exo- or the endonuclease activity, but mutation of these residues increased the dissociation constant for the substrate from 5 nM to 200 nM (K196A) and 50 nM (K215A). Biochemical analysis demonstrated that K83 is absolutely required for exonucleolytic activity on single-stranded DNA but is not required for endonucleolytic cleavage of flap structures. Structural analysis of this mutant by x-ray crystallography showed no significant perturbations around the metal-binding sites in the active site. The wild-type protein has different pH optima for endonuclease and exonuclease activities. Taken together, these results suggest that different mechanisms for endo- and exonucleolytic hydrolysis are used by this multifunctional enzyme.
About this Structure
1XO1 is a Single protein structure of sequence from Enterobacteria phage t5. Full crystallographic information is available from OCA.
Reference
Mutagenesis of conserved lysine residues in bacteriophage T5 5'-3' exonuclease suggests separate mechanisms of endo-and exonucleolytic cleavage., Garforth SJ, Ceska TA, Suck D, Sayers JR, Proc Natl Acad Sci U S A. 1999 Jan 5;96(1):38-43. PMID:9874768 Page seeded by OCA on Sat May 3 15:16:57 2008
