Anaerobic ammonium-oxidizing (anammox) bacteria express a distinct acyl carrier protein implicated in the biosynthesis of the highly unusual “ladderane” lipids these organisms produce. This “anammox-specific” ACP, or amxACP, shows several unique features such as a conserved FF motif and an unusual sequence in the functionally important helix III. Investigation of the protein's structure and dynamics, both in the crystal by ensemble refinement and by MD simulations, reveals that helix III adopts a rare six-residue-long 3₁₀-helical conformation that confers a large degree of conformational and positional variability on this part of the protein. This way of introducing structural flexibility by using the inherent properties of 3₁₀-helices appears unique among ACPs. Moreover, the structure suggests a role for the FF motif in shielding the thioester linkage between the protein's prosthetic group and its acyl cargo from hydrolysis.

中文翻译：

---

梯形脂质合成生物中一种不寻常的酰基载体蛋白的动力学

厌氧氨氧化（anammox）细菌表达一种独特的酰基载体蛋白，该蛋白与这些生物体产生的极不寻常的“ladderane”脂质的生物合成有关。这种“anammox 特异性”ACP 或 amxACP 显示出几个独特的特征，例如保守的 FF 基序和功能重要的螺旋 III 中的不寻常序列。通过整体细化和 MD 模拟对晶体中蛋白质结构和动力学的研究表明，螺旋 III 采用罕见的六残基长 3 ₁₀螺旋构象，该构象赋予这部分很大程度的构象和位置可变性的蛋白质。这种利用 3 _{10的固有特性引入结构灵活性的方式}-螺旋在 ACP 中显得独一无二。此外，该结构表明 FF 基序在保护蛋白质的辅基与其酰基货物之间的硫酯键免受水解方面的作用。