6Q5G

The ABC transporter associated binding protein from B. animalis subsp. lactis Bl-04 without ligand. SeMet variant

6Q5G の概要

• エントリーDOI: 10.2210/pdb6q5g/pdb
• 関連するPDBエントリー: 6H0H
• 分子名称: Sugar ABC transporter substrate-binding protein (2 entities in total)
• 機能のキーワード: complex, abc transporter, phasing, sugar binding protein
• 由来する生物種: Bifidobacterium animalis subsp. lactis BB-12
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 93445.30

構造登録者

Fredslund, F.,Lo Leggio, L. (登録日: 2018-12-08, 公開日: 2019-06-19, 最終更新日: 2024-11-06)

主引用文献

Theilmann, M.C.,Fredslund, F.,Svensson, B.,Lo Leggio, L.,Abou Hachem, M.
Substrate preference of an ABC importer corresponds to selective growth on beta-(1,6)-galactosides inBifidobacterium animalissubsp.lactis.
J.Biol.Chem., 294:11701-11711, 2019

PubMed Abstract: Bifidobacteria are exposed to substantial amounts of dietary β-galactosides. Distinctive preferences for growth on different β-galactosides are observed within members, but the basis of these preferences remains unclear. We previously described the first β-(1,6)/(1,3)-galactosidase from subsp. Bl-04. This enzyme is relatively promiscuous, exhibiting only 5-fold higher efficiency on the preferred β-(1,6)-galactobiose than the β-(1,4) isomer. Here, we characterize the solute-binding protein (6GBP) that governs the specificity of the ABC transporter encoded by the same β-galactoside utilization locus. We observed that although 6GBP recognizes both β-(1,6)- and β-(1,4)-galactobiose, 6GBP has a 1630-fold higher selectivity for the former, reflected in dramatic differences in growth, with several hours lag on less preferred β-(1,4)- and β-(1,3)-galactobiose. Experiments performed in the presence of varying proportions of β-(1,4)/β-(1,6)-galactobioses indicated that the preferred substrate was preferentially depleted from the culture supernatant. This established that the poor growth on the nonpreferred β-(1,4) was due to inefficient uptake. We solved the structure of 6GBP in complex with β-(1,6)-galactobiose at 1.39 Å resolution, revealing the structural basis of this strict selectivity. Moreover, we observed a close evolutionary relationship with the human milk disaccharide lacto--biose-binding protein from , indicating that the recognition of the nonreducing galactosyl is essentially conserved, whereas the adjacent position is diversified to fit different glycosidic linkages and monosaccharide residues. These findings indicate that oligosaccharide uptake has a pivotal role in governing selectivity for distinct growth substrates and have uncovered evolutionary trajectories that shape the diversification of sugar uptake proteins within .

PubMed: 31186348
DOI: 10.1074/jbc.RA119.008843

実験手法

X-RAY DIFFRACTION (2 Å)