3MBT

Structure of monomeric Blc from E. coli

3MBT の概要

• エントリーDOI: 10.2210/pdb3mbt/pdb
• 関連するPDBエントリー: 1QWD 2ACO
• 分子名称: Outer membrane lipoprotein blc (2 entities in total)
• 機能のキーワード: bacterial outer membrane lipoprotein, beta-barrel, lipid membrane anchor, lipocalin, lipid binding protein, membrane protein
• 由来する生物種: Escherichia coli
• 細胞内の位置: Cell outer membrane; Lipid-anchor: P0A901
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 19129.39

構造登録者

Schiefner, A.,Skerra, A. (登録日: 2010-03-26, 公開日: 2010-12-08, 最終更新日: 2023-09-06)

主引用文献

Schiefner, A.,Chatwell, L.,Breustedt, D.A.,Skerra, A.
Structural and biochemical analyses reveal a monomeric state of the bacterial lipocalin Blc.
Acta Crystallogr.,Sect.D, 66:1308-1315, 2010

PubMed Abstract: The first bacterial member of the lipocalin protein family, Blc, was identified in Escherichia coli as an outer membrane lipoprotein that is expressed under conditions of environmental stress. Previous crystallographic studies in space group P2₁2₁2₁ with two molecules per asymmetric unit, supported by static light-scattering experiments in solution, indicated that Blc may form a functional homodimer with lysophospholipid binding activity. Here, a new crystal structure of recombinant Blc in space group I4₁22 with one molecule in the asymmetric unit is described. The crystal packing differs considerably from that observed previously, which was determined using an N-terminally extended version of Blc dubbed `Blc-X'. In particular, the characteristic large interface region that was previously described as being responsible for stable dimer formation is absent in the I4₁22 crystal structure. Thus, the dimerization behaviour of Blc-X was most likely to be caused by the additional N-terminal peptide segment resulting from the cloning strategy employed. In contrast, we used a native-like N-terminus for Blc with just the lipid-anchored first Cys residue replaced by Ala. The fully monomeric status of this recombinant version of Blc in solution was confirmed by size-exclusion chromatography as well as analytical ultracentrifugation. Consequently, these data shed new light on the previously postulated lipid-binding mechanism and biological role of Blc. Beyond this, our findings illustrate that cloning artefacts, which frequently result from recombinant protein production for structural studies, must be considered with special caution when interpreting oligomerization and/or conformational effects.

PubMed: 21123871
DOI: 10.1107/S0907444910039375

実験手法

X-RAY DIFFRACTION (2.6 Å)