Topological analysis of Hedgehog acyltransferase, a multipalmitoylated transmembrane protein.
Topological analysis of Hedgehog acyltransferase, a multipalmitoylated transmembrane protein.
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DOI：
10.1074/jbc.m114.614578
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发表时间：
2015-02-06
期刊：
影响因子：
--
通讯作者：
Magee AI
中科院分区：
文献类型：
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作者：
Konitsiotis AD;Jovanović B;Ciepla P;Spitaler M;Lanyon-Hogg T;Tate EW;Magee AI
背景：刺猬酰基转移酶（HHAT）棕榈酰化刺猬蛋白，是一个潜在的癌症靶点。结果：HHAT具有10个跨膜结构域、2个折返环和4个棕榈酰化位点。结论：HHAT的拓扑结构确定，蛋白质被多棕榈酰化，从而调节蛋白质的功能。重要性：阐明HHAT的拓扑结构和翻译后修饰对于了解其酰基转移酶活性和开发治疗癌症的新策略至关重要。Hedgehog蛋白是一种分泌的形态发生蛋白，在发育和疾病中起着关键作用。在通过分泌途径的蛋白质成熟期间，它们通过添加N-末端棕榈酸和C-末端胆固醇部分而被修饰，这两者对于它们的正确功能和定位都是至关重要的。刺猬酰基转移酶（HHAT）是内质网中棕榈酰化刺猬蛋白的酶，是酰化分泌蛋白的膜结合0-酰基转移酶蛋白的小亚家族的成员，并且是癌症中的重要药物靶标。然而，对HHAT的结构和功能模式知之甚少。我们发现，HHAT是由10个跨膜结构域和两个折返环的关键His和Asp残基的内质网膜的相对两侧。我们进一步表明，HHAT是棕榈酰化的多个胞质半胱氨酸，保持蛋白质结构内的膜。最后，我们提供的证据表明，在假设的催化结构域中的保守的His残基的突变导致HHAT棕榈酰化的完全丧失，提供了新的见解如何蛋白质可能在体内发挥作用。
Background: Hedgehog acyltransferase (HHAT) palmitoylates hedgehog proteins and is a potential target in cancer. Results: HHAT has ten transmembrane domains, two reentrant loops, and four palmitoylation sites. Conclusion: HHAT topology is determined, and protein is multipalmitoylated, which modulates protein function. Significance: Elucidating HHAT topology and posttranslational modifications is crucial to understand its acyltransferase activity and to develop new strategies to treat cancer. Hedgehog proteins are secreted morphogens that play critical roles in development and disease. During maturation of the proteins through the secretory pathway, they are modified by the addition of N-terminal palmitic acid and C-terminal cholesterol moieties, both of which are critical for their correct function and localization. Hedgehog acyltransferase (HHAT) is the enzyme in the endoplasmic reticulum that palmitoylates Hedgehog proteins, is a member of a small subfamily of membrane-bound O-acyltransferase proteins that acylate secreted proteins, and is an important drug target in cancer. However, little is known about HHAT structure and mode of function. We show that HHAT is comprised of ten transmembrane domains and two reentrant loops with the critical His and Asp residues on opposite sides of the endoplasmic reticulum membrane. We further show that HHAT is palmitoylated on multiple cytosolic cysteines that maintain protein structure within the membrane. Finally, we provide evidence that mutation of the conserved His residue in the hypothesized catalytic domain results in a complete loss of HHAT palmitoylation, providing novel insights into how the protein may function in vivo.