1me5
From Proteopedia
(New page: 200px<br /><applet load="1me5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1me5, resolution 2.4Å" /> '''Crystal Structure of ...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:1me5.jpg|left|200px]]<br /><applet load="1me5" size=" | + | [[Image:1me5.jpg|left|200px]]<br /><applet load="1me5" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1me5, resolution 2.4Å" /> | caption="1me5, resolution 2.4Å" /> | ||
'''Crystal Structure of Mycobacterium Tuberculosis Alkylperoxidase AhpD H132Q Mutant'''<br /> | '''Crystal Structure of Mycobacterium Tuberculosis Alkylperoxidase AhpD H132Q Mutant'''<br /> | ||
==Overview== | ==Overview== | ||
| - | AhpD, a protein with two cysteine residues, is required for physiological | + | AhpD, a protein with two cysteine residues, is required for physiological reduction of the Mycobacterium tuberculosis alkylhydroperoxidase AhpC. AhpD also has an alkylhydroperoxidase activity of its own. The AhpC/AhpD system provides critical antioxidant protection, particularly in the absence of the catalase-peroxidase KatG, which is suppressed in most isoniazid-resistant strains. Based on the crystal structure, we proposed recently a catalytic mechanism for AhpD involving a proton relay in which the Glu118 carboxylate group, via His137 and a water molecule, deprotonates the catalytic residue Cys133 (Nunn, C. M., Djordjevic, S., Hillas, P. J., Nishida, C., and Ortiz de Montellano, P. R. (2002) J. Biol. Chem. 277, 20033-20040). A possible role for His132 in subsequent formation of the Cys133-Cys130 disulfide bond was also noted. To test this proposed mechanism, we have expressed the H137F, H137Q, H132F, H132Q, E118F, E118Q, C133S, and C130S mutants of AhpD, determined the crystal structures of the H137F and H132Q mutants, estimated the pKa values of the cysteine residues, and defined the kinetic properties of the mutant proteins. The collective results strongly support the proposed catalytic mechanism for AhpD. |
==About this Structure== | ==About this Structure== | ||
| - | 1ME5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis]. Full crystallographic information is available from [http:// | + | 1ME5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ME5 OCA]. |
==Reference== | ==Reference== | ||
| Line 14: | Line 14: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Djordjevic, S.]] | [[Category: Djordjevic, S.]] | ||
| - | [[Category: Montellano, P | + | [[Category: Montellano, P R.Ortiz de.]] |
| - | [[Category: Nunn, C | + | [[Category: Nunn, C M.]] |
[[Category: alpha helical]] | [[Category: alpha helical]] | ||
[[Category: trimer]] | [[Category: trimer]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:54:18 2008'' |
Revision as of 11:54, 21 February 2008
|
Crystal Structure of Mycobacterium Tuberculosis Alkylperoxidase AhpD H132Q Mutant
Overview
AhpD, a protein with two cysteine residues, is required for physiological reduction of the Mycobacterium tuberculosis alkylhydroperoxidase AhpC. AhpD also has an alkylhydroperoxidase activity of its own. The AhpC/AhpD system provides critical antioxidant protection, particularly in the absence of the catalase-peroxidase KatG, which is suppressed in most isoniazid-resistant strains. Based on the crystal structure, we proposed recently a catalytic mechanism for AhpD involving a proton relay in which the Glu118 carboxylate group, via His137 and a water molecule, deprotonates the catalytic residue Cys133 (Nunn, C. M., Djordjevic, S., Hillas, P. J., Nishida, C., and Ortiz de Montellano, P. R. (2002) J. Biol. Chem. 277, 20033-20040). A possible role for His132 in subsequent formation of the Cys133-Cys130 disulfide bond was also noted. To test this proposed mechanism, we have expressed the H137F, H137Q, H132F, H132Q, E118F, E118Q, C133S, and C130S mutants of AhpD, determined the crystal structures of the H137F and H132Q mutants, estimated the pKa values of the cysteine residues, and defined the kinetic properties of the mutant proteins. The collective results strongly support the proposed catalytic mechanism for AhpD.
About this Structure
1ME5 is a Single protein structure of sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA.
Reference
The mechanism of Mycobacterium tuberculosis alkylhydroperoxidase AhpD as defined by mutagenesis, crystallography, and kinetics., Koshkin A, Nunn CM, Djordjevic S, Ortiz de Montellano PR, J Biol Chem. 2003 Aug 8;278(32):29502-8. Epub 2003 May 21. PMID:12761216
Page seeded by OCA on Thu Feb 21 13:54:18 2008
