7ML5

Structure of the Starch Branching Enzyme I (BEI) complexed with maltododecaose from Oryza sativa L

7ML5 の概要

• エントリーDOI: 10.2210/pdb7ml5/pdb
• 分子名称: Isoform 2 of 1,4-alpha-glucan-branching enzyme, chloroplastic/amyloplastic, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, ... (4 entities in total)
• 機能のキーワード: rbei, maltododecaose, branching enzyme i, transferase, transferase-substrate complex, transferase/substrate
• 由来する生物種: Oryza sativa subsp. japonica (Rice)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 83731.76

構造登録者

Nayebi Gavgani, H.,Fawaz, R.,Geiger, J.H. (登録日: 2021-04-27, 公開日: 2021-11-17, 最終更新日: 2023-10-18)

主引用文献

Gavgani, H.N.,Fawaz, R.,Ehyaei, N.,Walls, D.,Pawlowski, K.,Fulgos, R.,Park, S.,Assar, Z.,Ghanbarpour, A.,Geiger, J.H.
A structural explanation for the mechanism and specificity of plant branching enzymes I and IIb.
J.Biol.Chem., 298:101395-101395, 2021

PubMed Abstract: Branching enzymes (BEs) are essential in the biosynthesis of starch and glycogen and play critical roles in determining the fine structure of these polymers. The substrates of these BEs are long carbohydrate chains that interact with these enzymes via multiple binding sites on the enzyme's surface. By controlling the branched-chain length distribution, BEs can mediate the physiological properties of starch and glycogen moieties; however, the mechanism and structural determinants of this specificity remain mysterious. In this study, we identify a large dodecaose binding surface on rice BE I (BEI) that reaches from the outside of the active site to the active site of the enzyme. Mutagenesis activity assays confirm the importance of this binding site in enzyme catalysis, from which we conclude that it is likely the acceptor chain binding site. Comparison of the structures of BE from Cyanothece and BE1 from rice allowed us to model the location of the donor-binding site. We also identified two loops that likely interact with the donor chain and whose sequences diverge between plant BE1, which tends to transfer longer chains, and BEIIb, which transfers exclusively much shorter chains. When the sequences of these loops were swapped with the BEIIb sequence, rice BE1 also became a short-chain transferring enzyme, demonstrating the key role these loops play in specificity. Taken together, these results provide a more complete picture of the structure, selectivity, and activity of BEs.

PubMed: 34762912
DOI: 10.1016/j.jbc.2021.101395

実験手法

X-RAY DIFFRACTION (2.35 Å)