2muc
From Proteopedia
(New page: 200px<br /><applet load="2muc" size="450" color="white" frame="true" align="right" spinBox="true" caption="2muc, resolution 2.30Å" /> '''MUCONATE CYCLOISOMER...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:2muc.jpg|left|200px]]<br /><applet load="2muc" size=" | + | [[Image:2muc.jpg|left|200px]]<br /><applet load="2muc" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2muc, resolution 2.30Å" /> | caption="2muc, resolution 2.30Å" /> | ||
'''MUCONATE CYCLOISOMERASE VARIANT F329I'''<br /> | '''MUCONATE CYCLOISOMERASE VARIANT F329I'''<br /> | ||
==Overview== | ==Overview== | ||
| - | We have refined to 2.3 A resolution two muconate cycloisomerase (MCIase) | + | We have refined to 2.3 A resolution two muconate cycloisomerase (MCIase) variant structures, F329I and I54V, that differ from each other and from wild-type in their activity toward cis,cis-muconate (CCM) and substituted CCMs. The working and free R-factors for F329I are 17.4/21.6% and for I54V, 17.6/22.3% with good stereochemistry. Except for the mutated residue, there are no significant changes in structure. To understand the differences in enzymatic properties we docked substituted CCMs and CCM into the active sites of the variants and wild type. The extra space the mutations create appears to account for most of the enzymatic differences. The lack of other structural changes explains why, although structurally equivalent changes occur in chloromuconate cycloisomerase (CMCIase), the changes in themselves do not convert a MCIase into a dehalogenating CMCIase. Reanalysis of the CMCIase structure revealed only one general acid/base, K169. The structural implication is that, in 2-chloro-CCM conversion by CMCIase, the lactone ring of 5-chloromuconolactone rotates before dehalogenation to bring the acidic C4 proton next to K169. Therefore, K169 alone performs both required protonation and deprotonation steps, the first at C5 as in MCIase, and the second, after ring rotation, at C4. This distinguishes CMCIase from alpha/beta barrel isomerases and racemases, which use two different bases. |
==About this Structure== | ==About this Structure== | ||
| - | 2MUC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_putida Pseudomonas putida] with MN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Muconate_cycloisomerase Muconate cycloisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.5.1.1 5.5.1.1] Full crystallographic information is available from [http:// | + | 2MUC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_putida Pseudomonas putida] with <scene name='pdbligand=MN:'>MN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Muconate_cycloisomerase Muconate cycloisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.5.1.1 5.5.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2MUC OCA]. |
==Reference== | ==Reference== | ||
| Line 24: | Line 24: | ||
[[Category: variant]] | [[Category: variant]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:08:00 2008'' |
Revision as of 16:08, 21 February 2008
|
MUCONATE CYCLOISOMERASE VARIANT F329I
Overview
We have refined to 2.3 A resolution two muconate cycloisomerase (MCIase) variant structures, F329I and I54V, that differ from each other and from wild-type in their activity toward cis,cis-muconate (CCM) and substituted CCMs. The working and free R-factors for F329I are 17.4/21.6% and for I54V, 17.6/22.3% with good stereochemistry. Except for the mutated residue, there are no significant changes in structure. To understand the differences in enzymatic properties we docked substituted CCMs and CCM into the active sites of the variants and wild type. The extra space the mutations create appears to account for most of the enzymatic differences. The lack of other structural changes explains why, although structurally equivalent changes occur in chloromuconate cycloisomerase (CMCIase), the changes in themselves do not convert a MCIase into a dehalogenating CMCIase. Reanalysis of the CMCIase structure revealed only one general acid/base, K169. The structural implication is that, in 2-chloro-CCM conversion by CMCIase, the lactone ring of 5-chloromuconolactone rotates before dehalogenation to bring the acidic C4 proton next to K169. Therefore, K169 alone performs both required protonation and deprotonation steps, the first at C5 as in MCIase, and the second, after ring rotation, at C4. This distinguishes CMCIase from alpha/beta barrel isomerases and racemases, which use two different bases.
About this Structure
2MUC is a Single protein structure of sequence from Pseudomonas putida with as ligand. Active as Muconate cycloisomerase, with EC number 5.5.1.1 Full crystallographic information is available from OCA.
Reference
Structural basis for the activity of two muconate cycloisomerase variants toward substituted muconates., Schell U, Helin S, Kajander T, Schlomann M, Goldman A, Proteins. 1999 Jan 1;34(1):125-36. PMID:10336378
Page seeded by OCA on Thu Feb 21 18:08:00 2008
