2HF5

The structure and function of a novel two-site calcium-binding fragment of calmodulin

2HF5 の概要

• エントリーDOI: 10.2210/pdb2hf5/pdb
• 関連するPDBエントリー: 1AK8 1CLL 1FW4 1PRW 3CLN
• 分子名称: Calmodulin, CALCIUM ION (2 entities in total)
• 機能のキーワード: calmodulin fragment, calcium-binding, ef-hand, calmodulin, hlh, metal binding protein
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Cytoplasm, cytoskeleton, spindle: P62158
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 7788.70

構造登録者

Lakowski, T.M.,Lee, G.M.,Reid, R.E.,McIntosh, L.P. (登録日: 2006-06-23, 公開日: 2007-05-01, 最終更新日: 2024-05-29)

主引用文献

Lakowski, T.M.,Lee, G.M.,Okon, M.,Reid, R.E.,McIntosh, L.P.
Calcium-induced folding of a fragment of calmodulin composed of EF-hands 2 and 3
Protein Sci., 16:1119-1132, 2007

PubMed Abstract: Calmodulin (CaM) is an EF-hand protein composed of two calcium (Ca(2+))-binding EF-hand motifs in its N-domain (EF-1 and EF-2) and two in its C-domain (EF-3 and EF-4). In this study, we examined the structure, dynamics, and Ca(2+)-binding properties of a fragment of CaM containing only EF-2 and EF-3 and the intervening linker sequence (CaM2/3). Based on NMR spectroscopic analyses, Ca(2+)-free CaM2/3 is predominantly unfolded, but upon binding Ca(2+), adopts a monomeric structure composed of two EF-hand motifs bridged by a short antiparallel beta-sheet. Despite having an "even-odd" pairing of EF-hands, the tertiary structure of CaM2/3 is similar to both the "odd-even" paired N- and C-domains of Ca(2+)-ligated CaM, with the conformationally flexible linker sequence adopting the role of an inter-EF-hand loop. However, unlike either CaM domain, CaM2/3 exhibits stepwise Ca(2+) binding with a K (d1) = 30 +/- 5 microM to EF-3, and a K (d2) > 1000 microM to EF-2. Binding of the first equivalent of Ca(2+) induces the cooperative folding of CaM2/3. In the case of native CaM, stacking interactions between four conserved aromatic residues help to hold the first and fourth helices of each EF-hand domain together, while the loop between EF-hands covalently tethers the second and third helices. In contrast, these aromatic residues lie along the second and third helices of CaM2/3, and thus are positioned adjacent to the loop between its "even-odd" paired EF-hands. This nonnative hydrophobic core packing may contribute to the weak Ca(2+) affinity exhibited by EF-2 in the context of CaM2/3.

PubMed: 17473011
DOI: 10.1110/ps.072777107

実験手法

SOLUTION NMR