Luftig R B, Lundh N P
Proc Natl Acad Sci U S A. 1973 Jun;70(6):1636-40. doi: 10.1073/pnas.70.6.1636.
A lysozyme-detergent procedure was developed for isolation of tau-particles from cells infected by gene-21 mutants of T4 bacteriophage. These particles have a sedimentation coefficient of 440 +/- 10 S. They contain less than 1% detectable nuclease-resistant DNA, are smaller (650 x 850 A) than normal bacteriophage heads (800 x 1100 A), and exhibit two major bands on 7.5% Na dodecyl sulfate-acrylamide gels. The more prominent band (55,000 daltons) corresponds to the uncleaved, major capsid polypeptide (P23); the other band (32,000 daltons) corresponds to the gene-22 product (P22). Temperature-shift experiments with cells infected with tsN8 (gene 21) mutants were used to study the fate of tau-particles accumulated under nonpermissive conditions. 50 Min after ts N8-infected cells were shifted from the nonpermissive (41.5 degrees ) to the permissive (25 degrees ) temperature, a phage burst occurred that was 75% of that observed with wild-type phage. However, in "pulse-chase" temperature-shift experiments, the radioactive tau-particle peak only slightly decreased (by 10-14%) by 50 min after the shift, whereas an increased amount of radioactivity (about four times as much as the tau-particle decrease) appeared in phage particles. The results suggest that at least two pools of head polypeptides coexist in cells infected with gene-21 mutants. One pool is composed of head subunits assembled into tau-particles, which are mostly aberrant structures; the second pool is composed of head subunits that are incorporated into mature phage when the gene-21 product becomes functional.
开发了一种溶菌酶-去污剂方法，用于从感染T4噬菌体基因21突变体的细胞中分离tau颗粒。这些颗粒的沉降系数为440±10 S。它们含有不到1%可检测到的耐核酸酶DNA，比正常噬菌体头部（800×1100 Å）小（650×850 Å），并且在7.5%十二烷基硫酸钠-丙烯酰胺凝胶上呈现两条主要条带。较突出的条带（55,000道尔顿）对应于未切割的主要衣壳多肽（P23）；另一条带（32,000道尔顿）对应于基因22产物（P22）。用感染tsN8（基因21）突变体的细胞进行温度转换实验，以研究在非允许条件下积累的tau颗粒的命运。ts N8感染的细胞从非允许温度（41.5摄氏度）转移到允许温度（25摄氏度）50分钟后，发生了噬菌体爆发，其爆发量为野生型噬菌体观察值的75%。然而，在“脉冲追踪”温度转换实验中，放射性tau颗粒峰值在转换后50分钟仅略有下降（下降10 - 14%），而噬菌体颗粒中出现了增加的放射性（约为tau颗粒下降量的四倍）。结果表明，在感染基因21突变体的细胞中至少存在两池头部多肽。一池由组装成tau颗粒的头部亚基组成，这些颗粒大多是异常结构；第二池由当基因21产物发挥功能时整合到成熟噬菌体中的头部亚基组成。
