Institute of Chemistry, the Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
Department of Biotechnology and Food Engineering, Technion, Haifa, 3200, Israel.
Commun Biol. 2022 May 16;5(1):465. doi: 10.1038/s42003-022-03054-z.
AbnA is an extracellular GH43 α-L-arabinanase from Geobacillus stearothermophilus, a key bacterial enzyme in the degradation and utilization of arabinan. We present herein its full-length crystal structure, revealing the only ultra-multimodular architecture and the largest structure to be reported so far within the GH43 family. Additionally, the structure of AbnA appears to contain two domains belonging to new uncharacterized carbohydrate-binding module (CBM) families. Three crystallographic conformational states are determined for AbnA, and this conformational flexibility is thoroughly investigated further using the "integrative structure determination" approach, integrating molecular dynamics, metadynamics, normal mode analysis, small angle X-ray scattering, dynamic light scattering, cross-linking, and kinetic experiments to reveal large functional conformational changes for AbnA, involving up to ~100 Å movement in the relative positions of its domains. The integrative structure determination approach demonstrated here may apply also to the conformational study of other ultra-multimodular proteins of diverse functions and structures.
AbnA 是一种来自嗜热脂肪地芽孢杆菌的胞外 GH43 α-L-阿拉伯聚糖酶，是阿拉伯聚糖降解和利用中的关键细菌酶。本文介绍了它的全长晶体结构，揭示了 GH43 家族中唯一的超多功能模块结构和迄今为止报道的最大结构。此外，AbnA 的结构似乎包含两个属于新的未表征的碳水化合物结合模块（CBM）家族的结构域。确定了 AbnA 的三种晶体构象状态，并使用“综合结构测定”方法进一步深入研究了这种构象灵活性，该方法整合了分子动力学、元动力学、正常模式分析、小角度 X 射线散射、动态光散射、交联和动力学实验，以揭示 AbnA 的大功能构象变化，涉及其结构域相对位置的高达~100 Å 的运动。本文展示的综合结构测定方法也可应用于其他具有不同功能和结构的超多功能蛋白的构象研究。
