1P5C
Circular permutation of Helix A in T4 lysozyme
Summary for 1P5C
| Entry DOI | 10.2210/pdb1p5c/pdb |
| Related | 1JTM 1OYU 1P56 262L |
| Descriptor | Lysozyme (2 entities in total) |
| Functional Keywords | circular permutation, protein design, context dependent folding, hydrolase |
| Biological source | Enterobacteria phage T4 |
| Total number of polymer chains | 4 |
| Total formula weight | 75446.43 |
| Authors | Sagermann, M.,Gay, L.,Baase, W.A.,Matthews, B.W. (deposition date: 2003-04-25, release date: 2004-05-04, Last modification date: 2023-08-16) |
| Primary citation | Sagermann, M.,Baase, W.A.,Mooers, B.H.,Gay, L.,Matthews, B.W. Relocation or duplication of the helix A sequence of T4 lysozyme causes only modest changes in structure but can increase or decrease the rate of folding. Biochemistry, 43:1296-1301, 2004 Cited by PubMed Abstract: In T4 lysozyme, helix A is located at the amino terminus of the sequence but is associated with the C-terminal domain in the folded structure. To investigate the implications of this arrangement for the folding of the protein, we first created a circularly permuted variant with a new amino terminus at residue 12. In effect, this moves the sequence corresponding to helix A from the N- to the C-terminus of the molecule. The protein crystallized nonisomorphously with the wild type but has a very similar structure, showing that the unit consisting of helix A and the C-terminal domain can be reconstituted from a contiguous polypeptide chain. The protein is less stable than the wild type but folds slightly faster. We then produced a second variant in which the helix A sequence was appended at the C-terminus (as in the first variant), but was also restored at the N-terminus (as in the wild type). This variant has two helix A sequences, one at the N-terminus and the other at the C-terminus, each of which can compete for the same site in the folded protein. The crystal structure shows that it is the N-terminal sequence that folds in a manner similar to that of the wild type, whereas the copy at the C-terminus is forced to loop out. The stability of this protein is much closer to that of the wild type, but its rate of folding is significantly slower. The reduction in rate is attributed to the presence of the two identical sequence segments which compete for a single, mutually exclusive, site. PubMed: 14756565DOI: 10.1021/bi035702q PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.5 Å) |
Structure validation
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