Crystal structures of Val58Ile tryptophan repressor in a domain-swapped array in the presence and absence of l-tryptophan,Acta Crystallographica Section F

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Crystal structures of Val58Ile tryptophan repressor in a domain-swapped array in the presence and absence of l-tryptophan
Acta Crystallographica Section F ( IF 1.1 ) Pub Date : 2021-07-30 , DOI: 10.1107/s2053230x21006142
Janina Sprenger ₁ , Catherine L Lawson ₂ , Claes von Wachenfeldt ₃ , Leila Lo Leggio ₁ , Jannette Carey ₄

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The crystal structures of domain-swapped tryptophan repressor (TrpR) variant Val58Ile before and after soaking with the physiological ligand l-tryptophan (l-Trp) indicate that l-Trp occupies the same location in the domain-swapped form as in native dimeric TrpR and makes equivalent residue contacts. This result is unexpected because the ligand binding-site residues arise from three separate polypeptide chains in the domain-swapped form. This work represents the first published structure of a domain-swapped form of TrpR with l-Trp bound. The presented structures also show that the protein amino-terminus, whether or not it bears a disordered extension of about 20 residues, is accessible in the large solvent channels of the domain-swapped crystal form, as in the structures reported previously in this form for TrpR without N-terminal extensions. These findings inspire the exploration of l-Trp analogs and N-terminal modifications as labels to orient guest proteins that cannot otherwise be crystallized in the solvent channels of crystalline domain-swapped TrpR hosts for potential diffraction analysis.

中文翻译：

在存在和不存在 L-色氨酸的情况下，域交换阵列中 Val58Ile 色氨酸阻遏物的晶体结构

结构域交换色氨酸阻遏蛋白 (TrpR) 变体 Val58Ile 在用生理配体l-色氨酸 ( l -Trp) 浸泡之前和之后的晶体结构表明，l -Trp 在结构域交换形式中占据与天然二聚体 TrpR 中相同的位置并进行等效的残留接触。这个结果是出乎意料的，因为配体结合位点残基来自结构域交换形式的三个独立的多肽链。这项工作代表了第一个已发表的具有l - Trp 结合的 TrpR 结构域交换形式的结构。所呈现的结构还表明，蛋白质氨基末端，无论其是否具有约20个残基的无序延伸，都可以在结构域交换晶体形式的大溶剂通道中进入，如之前报道的这种形式的结构没有 N 末端延伸的 TrpR。这些发现激发了对l -Trp 类似物和 N 末端修饰的探索，作为标签来定向客体蛋白，否则这些客体蛋白不能在结晶域交换的 TrpR 宿主的溶剂通道中结晶，以进行潜在的衍射分析。

更新日期：2021-07-01

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