1ks3: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1ks3.gif|left|200px]] | [[Image:1ks3.gif|left|200px]] | ||
<!-- | |||
The line below this paragraph, containing "STRUCTURE_1ks3", 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_1ks3| PDB=1ks3 | SCENE= }} | ||
}} | |||
'''METHIONINE CORE MUTANT OF T4 LYSOZYME''' | '''METHIONINE CORE MUTANT OF T4 LYSOZYME''' | ||
| Line 34: | Line 31: | ||
[[Category: Quillin, M L.]] | [[Category: Quillin, M L.]] | ||
[[Category: Weaver, L H.]] | [[Category: Weaver, L H.]] | ||
[[Category: | [[Category: Methionine core mutant]] | ||
[[Category: Protein engineering]] | |||
[[Category: | [[Category: Protein folding]] | ||
[[Category: | [[Category: T4 lysozyme]] | ||
[[Category: | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:06:01 2008'' | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 23:06, 2 May 2008
METHIONINE CORE MUTANT OF T4 LYSOZYME
OverviewOverview
In order to further explore the tolerance of proteins to amino acid substitutions within the interior, a series of core residues was replaced by methionine within the C-terminal domain of T4 lysozyme. By replacing leucine, isoleucine, valine and phenylalanine residues a total of 10 methionines could be introduced, which corresponds to a third of the residues that are buried in this domain. As more methionines are incorporated the protein gradually loses stability. This is attributed in part to a reduction in hydrophobic stabilization, in part to the increased entropic cost of localizing the long, flexible methionine sidechains, and in part to steric clashes. The changes in structure of the mutants relative to the wildtype protein are modest but tend to increase in an additive fashion as more methionines are included. In the most extreme case, namely the 10-methionine mutant, much of the C-terminal domain remains quite similar to wildtype (root-mean-square backbone shifts of 0.56 A), while the F and G helices undergo rotations of approximately 20 degrees and center-of-mass shifts of approximately 1.4 A. For up to six methionine substitutions the changes in stability are additive. Beyond this point, however, the multiple mutants are somewhat more stable than suggested from the sum of their constituents, especially for those including the replacement Val111-->Met. This is interpreted in terms of the larger structural changes associated with this substitution. The substituted sidechains in the mutant structures have somewhat higher crystallographic thermal factors than their counterparts in WT*. Nevertheless, the interiors of the mutant proteins retain a well-defined structure with little suggestion of molten-globule characteristics. Lysozymes in which selenomethionine has been incorporated rather than methionine tend to have increased stability. At the same time they also fold faster. This provides further evidence that, at the rate-limiting step in folding, the structure of the C-terminal domain of T4 lysozyme is similar to that of the fully folded protein.
About this StructureAbout this Structure
1KS3 is a Single protein structure of sequence from Enterobacteria phage t4. Full crystallographic information is available from OCA.
ReferenceReference
Multiple methionine substitutions are tolerated in T4 lysozyme and have coupled effects on folding and stability., Gassner NC, Baase WA, Mooers BH, Busam RD, Weaver LH, Lindstrom JD, Quillin ML, Matthews BW, Biophys Chem. 2003;100(1-3):325-40. PMID:12646375 Page seeded by OCA on Fri May 2 23:06:01 2008