Activation of the Aspergillus PacC zinc finger transcription factor requires two proteolytic steps
Activation of the Aspergillus PacC zinc finger transcription factor requires two proteolytic steps
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DOI：
10.1093/emboj/21.6.1350
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发表时间：
2002-03-15
期刊：
影响因子：
11.4
通讯作者：
Peñalva, MA
中科院分区：
文献类型：
--
作者：
Díez, E;Alvaro, J;Peñalva, MA
曲霉PACC转录因子在碱性环境pH条件下进行蛋白水解性激活。在酸性环境中，674个残基的翻译产物采用封闭的构象，通过分子内相互作用保护不被激活，分子内相互作用涉及小于或等于150个残基的C-末端结构域。PH信令将PACC转换为可访问的构象，使其能够在残基252-254内进行加工切割。我们证明PACC的激活需要两个连续的蛋白分解步骤。首先，通过蛋白水解法消除C-末端，将“封闭的”翻译产物转化为可访问的、承诺的中间体。这种环境中pH调节的切割是最终的、不依赖于pH的加工反应所必需的，并且是由一个不同的信号酶(可能是PalB)介导的。信号转导酶在保守的24个残基的“信号转导酶盒”中，将PACC裂解在残基493和500之间。精确的缺失或Leu498Ser替换防止了已提交和已处理形式的形成，表明信号切割对于最终处理是必不可少的。相反，Leu340Ser蛋白的加工不需要信号切割，因为它缺乏阻止加工的相互作用。在其两步机制中，PACC处理可以与受控的膜内蛋白分解进行比较。
The Aspergillus PacC transcription factor undergoes proteolytic activation in response to alkaline ambient pH. In acidic environments, the 674 residue translation product adopts a 'closed' conformation, protected from activation through intramolecular interactions involving the less than or equal to150 residue C-terminal domain. pH signalling converts PacC to an accessible conformation enabling processing cleavage within residues 252-254. We demonstrate that activation of PacC requires two sequential proteolytic steps. First, the 'closed' translation product is converted to an accessible, committed intermediate by proteolytic elimination of the C-terminus. This ambient pH-regulated cleavage is required for the final, pH-independent processing reaction and is mediated by a distinct signalling protease (possibly PalB). The signalling protease cleaves PacC between residues 493 and 500, within a conserved 24 residue 'signalling protease box'. Precise deletion or Leu498Ser substitution prevents formation of the committed and processed forms, demonstrating that signalling cleavage is essential for final processing. In contrast, signalling cleavage is not required for processing of the Leu340Ser protein, which lacks interactions preventing processing. In its two-step mechanism, PacC processing can be compared with regulated intramembrane proteolysis.