Figure 3 - full size

 

Figure 3.
Figure 3. Conformational changes in the L16 loop and disruption of a salt-bridge are fingerprints of the active p38α molecules. (a) The conformational changes within the L16 loops of p38α^D176A + F327L (blue) and p38α^D176A + F327S (yellow) in reference to p38α^D176A (magenta) and p38α^wt (gray). Mutations of Phe327 to serine or leucine results in a conformational change in the L16 loop. Residues 327 in the mutants' structures subsequently adopt a different conformation. However, the conformation of Trp337 and Tyr69 remains highly similar in all structures. (b) Segments of L16 loop from p38α^D176A (left), p38α^D176A + F327L (center) and p38α^D176A + F327S (right) are superimposed with p38α^wt as a reference. The conformation of the L16 loop in the structure of p38α^D176A is almost identical (except minor changes in Asp331) to that of p38α^wt. Mutation of Phe327 leads to the unwinding and a shift of the main-chain helical conformation in the L16, and subsequently the side-chains of residues 324 to 330 adopt a different position in both p38α^D176A + F327L and p38α^D176A + F327S models (center and right). (c) A salt bridge interaction is formed between the negatively charged carboxyl group of Glu328 and the positively charged guanidine of Arg70 (green broken lines) in both p38α^wt and p38α^D176A (left). This salt bridge is disrupted in the structures of p38α^D176A + F327L and p38α^D176A + F327S (center and right, respectively) due to the conformational change in the L16 loop. In this regard, the unpaired Arg70 acquire new conformations; in p38α^D176A + F327L Arg70 adopts a dual conformation whereas in p38α^D176A + F327S only one. The C^α atom of Glu328 is shifted 2.53 Å and 1.11 Å in the structures of p38α^D176A + F327L and p38α^D176A + F327S, respectively, relative to the p38α^wt structure. The orientation of the side-chains is somewhat different as Lys66 is stabilizing the carbonyl oxygen of Glu328 by forming an H-bond interaction in p38α^D176A + F327S similar to p38α^wt but not in p38α^D176A + F327L (yellow broken lines). Figure 3. Conformational changes in the L16 loop and disruption of a salt-bridge are fingerprints of the active p38α molecules. (a) The conformational changes within the L16 loops of p38α^D176A + F327L (blue) and p38α^D176A + F327S (yellow) in reference to p38α^D176A (magenta) and p38α^wt (gray). Mutations of Phe327 to serine or leucine results in a conformational change in the L16 loop. Residues 327 in the mutants' structures subsequently adopt a different conformation. However, the conformation of Trp337 and Tyr69 remains highly similar in all structures. (b) Segments of L16 loop from p38α^D176A (left), p38α^D176A + F327L (center) and p38α^D176A + F327S (right) are superimposed with p38α^wt as a reference. The conformation of the L16 loop in the structure of p38α^D176A is almost identical (except minor changes in Asp331) to that of p38α^wt. Mutation of Phe327 leads to the unwinding and a shift of the main-chain helical conformation in the L16, and subsequently the side-chains of residues 324 to 330 adopt a different position in both p38α^D176A + F327L and p38α^D176A + F327S models (center and right). (c) A salt bridge interaction is formed between the negatively charged carboxyl group of Glu328 and the positively charged guanidine of Arg70 (green broken lines) in both p38α^wt and p38α^D176A (left). This salt bridge is disrupted in the structures of p38α^D176A + F327L and p38α^D176A + F327S (center and right, respectively) due to the conformational change in the L16 loop. In this regard, the unpaired Arg70 acquire new conformations; in p38α^D176A + F327L Arg70 adopts a dual conformation whereas in p38α^D176A + F327S only one. The C^α atom of Glu328 is shifted 2.53 Å and 1.11 Å in the structures of p38α^D176A + F327L and p38α^D176A + F327S, respectively, relative to the p38α^wt structure. The orientation of the side-chains is somewhat different as Lys66 is stabilizing the carbonyl oxygen of Glu328 by forming an H-bond interaction in p38α^D176A + F327S similar to p38α^wt but not in p38α^D176A + F327L (yellow broken lines).

The above figure is reprinted by permission from Elsevier: J Mol Biol (2007, 365, 66-76) copyright 2007.