Structural Biochemistry - Department of Chemistry, Philipps University Marburg, Hans-Meerwein Strasse 4, 35032 Marburg, Germany.
Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany.
Acta Crystallogr D Struct Biol. 2018 Nov 1;74(Pt 11):1105-1114. doi: 10.1107/S2059798318014146. Epub 2018 Oct 29.
The small winged helix-turn-helix (wHTH) proteins of the Lrs14 family are major transcriptional regulators and act as archaeal biofilm regulators (AbfRs) in the crenarchaeote Sulfolobus acidocaldarius. Here, the first crystal structure of an AbfR ortholog, AbfR2, the deletion of which is known to impair biofilm formation, is presented. Like most other wHTH orthologs, AbfR2 is dimeric in solution as well as in its 2.45 Å resolution crystal structure. Given the presence of three independent AbfR2 dimers in the asymmetric unit, the crystal structure shows a considerable degree of conformational variation within the dimer, the antiparallel orientations of which are stabilized by coiled-coil interaction between H4 helices. Conserved anchor interactions between helices H0 and H4 of AbfR2 further contribute to dimer stabilization. The combined structural and bioinformatic analysis reveals cluster-specific structural differences between different members of the Lrs14 protein family.
小型翼状螺旋-转角-螺旋（wHTH）蛋白家族的 Lrs14 成员是主要的转录调控因子，在古菌 Sulfolobus acidocaldarius 中充当古细菌生物膜调控因子（AbfR）。在此，呈现了首个 AbfR 同源物 AbfR2 的晶体结构，已知该同源物的缺失会损害生物膜的形成。与大多数其他 wHTH 同源物一样，AbfR2 在溶液中和 2.45 Å 分辨率的晶体结构中都是二聚体。由于在不对称单元中存在三个独立的 AbfR2 二聚体，因此晶体结构显示出二聚体内部相当大的构象变化，其反平行取向通过 H4 螺旋之间的卷曲螺旋相互作用稳定。AbfR2 的 H0 和 H4 螺旋之间的保守锚定相互作用进一步有助于二聚体的稳定。综合结构和生物信息学分析揭示了 Lrs14 蛋白家族不同成员之间特定于簇的结构差异。
