REGULATION OF COAT PROTEIN POLYMERIZATION BY THE SCAFFOLDING PROTEIN OF BACTERIOPHAGE-P22
REGULATION OF COAT PROTEIN POLYMERIZATION BY THE SCAFFOLDING PROTEIN OF BACTERIOPHAGE-P22
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DOI：
10.1016/s0006-3495(80)84963-0
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发表时间：
1980-01-01
影响因子：
3.4
通讯作者：
KING, J
中科院分区：
文献类型：
--
作者：
FULLER, MT;KING, J
在双链 DNA 噬菌体的形态发生中，首先组装不含 DNA 的前体蛋白壳，然后填充 DNA。沙门氏菌噬菌体 P22 尺寸正确的前体外壳（衣壳）的组装需要约 420 个外壳蛋白亚基与约 200 个支架蛋白亚基相互作用，以形成支架蛋白位于内部的双壳颗粒。在 DNA 包装过程中，所有支架蛋白亚基均从衣壳中退出并参与进一步的衣壳组装（King 和 Casjens. 1974. Nature (Lond.). 251:112–119）。为了研究壳组装的机制，我们通过选择性解离分离的衣壳来纯化外壳和支架蛋白亚基。两种蛋白质均可在接近中性 pH 的 Tris 缓冲液中以可溶亚基形式获得。外壳蛋白在蔗糖梯度中沉积为大致球形单体，而支架蛋白则沉积为细长单体。当两种蛋白质在 1.5 M 盐酸胍中混合在一起并在室温下透析回缓冲液时，形成原衣壳，其在形态、沉降行为和蛋白质组成方面与体内形成的原衣壳非常相似。在相同条件下单独孵育任一蛋白质都不会产生任何大的结构。我们将这些结果解释为意味着壳的组装涉及两种蛋白质通过它们的相互作用从非聚集形式转变为聚集形式。研究结果根据形态发生中自我调节组装和蛋白质聚合控制的一般问题进行了讨论。
In the morphogenesis of double stranded DNA phages, a precursor protein shell empty of DNA is first assembled and then filled with DNA. The assembly of the correctly dimensioned precursor shell (procapsid) of Salmonella bacteriophage P22 requires the interaction of some 420 coat protein subunits with approximately 200 scaffolding protein subunits to form a double shelled particle with the scaffolding protein on the inside. In the course of DNA packaging, all of the scaffolding protein subunits exit from the procapsid and participate in further rounds of procapsid assembly (King and Casjens. 1974. Nature (Lond.). 251:112–119). To study the mechanism of shell assembly we have purified the coat and scaffolding protein subunits by selective dissociation of isolated procapsids. Both proteins can be obtained as soluble subunits in Tris buffer at near neutral pH. The coat protein sedimented in sucrose gradients as a roughly spherical monomer, while the scaffolding protein sedimented as if it were an elongated monomer. When the two proteins were mixed together in 1.5 M guanidine hydrochloride and dialyzed back to buffer at room temperature, procapsids formed which were very similar in morphology, sedimentation behavior, and protein composition to procapsids formed in vivo. Incubation of either protein alone under the same conditions did not yield any large structures. We interpret these results to mean that the assembly of the shell involves a switching of both proteins from their nonaggregating to their aggregating forms through their mutual interaction. The results are discussed in terms of the general problem of self-regulated assembly and the control of protein polymerization in morphogenesis.