1L5T

Crystal Structure of a Domain-Opened Mutant (R121D) of the Human Lactoferrin N-lobe Refined From a Merohedrally-Twinned Crystal Form.

1L5T の概要

• エントリーDOI: 10.2210/pdb1l5t/pdb
• 関連するPDBエントリー: 1cb6 1lct
• 分子名称: lactoferrin (2 entities in total)
• 機能のキーワード: iron transport, glycoprotein, lactoferrin, n-lobe, iron-release, twinning, metal transport
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Isoform 1: Secreted. Isoform DeltaLf: Cytoplasm: P02788
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 73843.75

構造登録者

Jameson, G.B.,Anderson, B.F.,Breyer, W.A.,Tweedie, J.W.,Baker, E.N. (登録日: 2002-03-07, 公開日: 2002-03-27, 最終更新日: 2024-11-13)

主引用文献

Jameson, G.B.,Anderson, B.F.,Breyer, W.A.,Day, C.L.,Tweedie, J.W.,Baker, E.N.
Structure of a domain-opened mutant (R121D) of the human lactoferrin N-lobe refined from a merohedrally twinned crystal form.
Acta Crystallogr.,Sect.D, 58:955-962, 2002

PubMed Abstract: Human lactoferrin is an iron-binding protein with a bilobal structure. Each lobe contains a high-affinity binding site for a single Fe(3+) ion and an associated CO(3)(2-) ion. Although iron binds very tightly, it can be released at low pH, with an accompanying conformational change in which the two domains move apart. The Arg121Asp (R121D) mutant of the N-lobe half-molecule of human lactoferrin was constructed in order to test whether the Asp121 side chain could substitute for the CO(3)(2-) ion at the iron-binding site. The R121D mutant protein was crystallized in its apo form as it lost iron during crystallization. The crystals were also merohedrally twinned, with a twin fraction close to 0.5. Starting from the initial molecular-replacement solution [Breyer et al. (1999), Acta Cryst. D55, 129-138], the structure has been refined at 3.0 A resolution to an R factor of 13.9% (R(free) of 19.9%). Despite the moderate resolution, the high solvent content and non-crystallographic symmetry contributed to electron-density maps of excellent quality. Weakened iron binding by the R121D mutant is explained by occlusion of the anion-binding site by the Asp side chain. The opening of the two domains in the apoR121D structure (a rotation of 54 degrees ) closely matches that of the N-lobe in full-length lactoferrin, showing that the extent of the conformational change depends on properties inherent to the N-lobe. Differences in the C-terminal portion of the N-lobe (residues 321-332) for apoR121D relative to the closed wild-type iron-bound structure point to the importance of this region in stabilizing the open form.

PubMed: 12037297
DOI: 10.1107/S0907444902005127

実験手法

X-RAY DIFFRACTION (3 Å)