1p5c

Circular permutation of Helix A in T4 lysozyme

spinqualitylabelsall models 1p5c, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1p5c is a 4 chain structure with sequence from Bpt4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1jtm, 1p56, 262l, 1oyu Gene: GENE E (BPT4) Activity: Lysozyme, with EC number 3.2.1.17 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [LYS_BPT4] Helps to release the mature phage particles from the cell wall by breaking down the peptidoglycan. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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. 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.,Sagermann M, Baase WA, Mooers BH, Gay L, Matthews BW Biochemistry. 2004 Feb 10;43(5):1296-301. PMID:14756565 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Lysozyme 3D structures

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