2vnd
From Proteopedia
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'''THE N69Q MUTANT OF VIBRIO CHOLERAE ENDONUCLEASE I''' | '''THE N69Q MUTANT OF VIBRIO CHOLERAE ENDONUCLEASE I''' | ||
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| + | ==Overview== | ||
| + | Adaptation to extreme environments affects the stability and catalytic efficiency of enzymes, often endowing them with great industrial potential. We compared the environmental adaptation of the secreted endonuclease I from the cold-adapted marine fish pathogen Vibrio salmonicida (VsEndA) and the human pathogen Vibrio cholerae (VcEndA). Kinetic analysis showed that VsEndA displayed unique halotolerance. It retained a considerable amount of activity from low concentrations to at least 0.6 m NaCl, and was adapted to work at higher salt concentrations than VcEndA by maintaining a low K(m) value and increasing k(cat). In differential scanning calorimetry, salt stabilized both enzymes, but the effect on the calorimetric enthalpy and cooperativity of unfolding was larger for VsEndA, indicating salt dependence. Mutation of DNA binding site residues (VsEndA, Q69N and K71N; VcEndA, N69Q and N71K) affected the kinetic parameters. The VsEndA Q69N mutation also increased the T(m) value, whereas other mutations affected mainly DeltaH(cal). The determined crystal structure of VcEndA N69Q revealed the loss of one hydrogen bond present in native VcEndA, but also the formation of a new hydrogen bond involving residue 69 that could possibly explain the similar T(m) values for native and N69Q-mutated VcEndA. Structural analysis suggested that the stability, catalytic efficiency and salt tolerance of EndA were controlled by small changes in the hydrogen bonding networks and surface electrostatic potential. Our results indicate that endonuclease I adaptation is closely coupled to the conditions of the habitats of natural Vibrio, with VsEndA displaying a remarkable salt tolerance unique amongst the endonucleases characterized so far. | ||
==About this Structure== | ==About this Structure== | ||
2VND is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Vibrio_cholerae Vibrio cholerae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2VND OCA]. | 2VND is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Vibrio_cholerae Vibrio cholerae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2VND OCA]. | ||
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| + | ==Reference== | ||
| + | Effects of salt on the kinetics and thermodynamic stability of endonuclease I from Vibrio salmonicida and Vibrio cholerae., Niiranen L, Altermark B, Brandsdal BO, Leiros HK, Helland R, Smalas AO, Willassen NP, FEBS J. 2008 Apr;275(7):1593-605. Epub 2008 Feb 27. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18312415 18312415] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Vibrio cholerae]] | [[Category: Vibrio cholerae]] | ||
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[[Category: Thermodynamic stability]] | [[Category: Thermodynamic stability]] | ||
[[Category: Vibrio]] | [[Category: Vibrio]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed May 7 08:53:01 2008'' |
Revision as of 05:53, 7 May 2008
THE N69Q MUTANT OF VIBRIO CHOLERAE ENDONUCLEASE I
Overview
Adaptation to extreme environments affects the stability and catalytic efficiency of enzymes, often endowing them with great industrial potential. We compared the environmental adaptation of the secreted endonuclease I from the cold-adapted marine fish pathogen Vibrio salmonicida (VsEndA) and the human pathogen Vibrio cholerae (VcEndA). Kinetic analysis showed that VsEndA displayed unique halotolerance. It retained a considerable amount of activity from low concentrations to at least 0.6 m NaCl, and was adapted to work at higher salt concentrations than VcEndA by maintaining a low K(m) value and increasing k(cat). In differential scanning calorimetry, salt stabilized both enzymes, but the effect on the calorimetric enthalpy and cooperativity of unfolding was larger for VsEndA, indicating salt dependence. Mutation of DNA binding site residues (VsEndA, Q69N and K71N; VcEndA, N69Q and N71K) affected the kinetic parameters. The VsEndA Q69N mutation also increased the T(m) value, whereas other mutations affected mainly DeltaH(cal). The determined crystal structure of VcEndA N69Q revealed the loss of one hydrogen bond present in native VcEndA, but also the formation of a new hydrogen bond involving residue 69 that could possibly explain the similar T(m) values for native and N69Q-mutated VcEndA. Structural analysis suggested that the stability, catalytic efficiency and salt tolerance of EndA were controlled by small changes in the hydrogen bonding networks and surface electrostatic potential. Our results indicate that endonuclease I adaptation is closely coupled to the conditions of the habitats of natural Vibrio, with VsEndA displaying a remarkable salt tolerance unique amongst the endonucleases characterized so far.
About this Structure
2VND is a Single protein structure of sequence from Vibrio cholerae. Full crystallographic information is available from OCA.
Reference
Effects of salt on the kinetics and thermodynamic stability of endonuclease I from Vibrio salmonicida and Vibrio cholerae., Niiranen L, Altermark B, Brandsdal BO, Leiros HK, Helland R, Smalas AO, Willassen NP, FEBS J. 2008 Apr;275(7):1593-605. Epub 2008 Feb 27. PMID:18312415 Page seeded by OCA on Wed May 7 08:53:01 2008
