Gamow R I, Kozloff L M
J Virol. 1968 May;2(5):480-7. doi: 10.1128/JVI.2.5.480-487.1968.
The treatment of bacteriophage T4D with 2-hydroxy-5-nitrobenzyl bromide, a specific reagent for alkylating the indole ring of tryptophan residues, converts these particles from a cofactor-independent form to a cofactor-sensitive form. These treated T4D particles phenotypically resemble T4B particles in certain respects. Their ability to form plaques on minimal medium plates is increased by the addition of l-tryptophan and is inhibited by the addition of indole. In liquid medium, their rate of adsorption is dependent on the presence of the cofactor l-tryptophan. l-Tryptophan-requiring phage have been produced by in vitro assembly of treated tail-fiberless particles of a T4D amber mutant plus untreated tail fiber preparation. When treated tail fibers were used with untreated tail-fiberless particles, the newly assembled particles did not require cofactor. A model of the tail structure of all the T-even bacteriophages is presented which postulates that the active configuration of the tail fibers requires that there be either (i) an endogenous tryptophan residue of the phage particle itself or (ii) an exogenously added l-tryptophan molecule complexed with a specific tryptophan receptor site, most likely on the phage base plate.
用2-羟基-5-硝基苄基溴（一种用于烷基化色氨酸残基吲哚环的特异性试剂）处理噬菌体T4D，可使这些颗粒从辅因子非依赖型转变为辅因子敏感型。这些经处理的T4D颗粒在某些方面表型上类似于T4B颗粒。在基本培养基平板上形成噬菌斑的能力会因添加L-色氨酸而增强，因添加吲哚而受到抑制。在液体培养基中，它们的吸附速率取决于辅因子L-色氨酸的存在。通过体外组装T4D琥珀突变体的经处理的无尾丝颗粒与未处理的尾丝制剂，已产生了需要L-色氨酸的噬菌体。当将经处理的尾丝与未处理的无尾丝颗粒一起使用时，新组装的颗粒不需要辅因子。本文提出了所有T偶数噬菌体尾部结构的模型，该模型假定尾丝的活性构型要求存在以下两种情况之一：（i）噬菌体颗粒本身的内源性色氨酸残基；或（ii）与特定色氨酸受体位点（很可能在噬菌体基板上）络合的外源性添加的L-色氨酸分子。
