Kania J, Müller-Hill B
Eur J Biochem. 1977 Oct 3;79(2):381-6. doi: 10.1111/j.1432-1033.1977.tb11819.x.
Escherichia coli heterogenotes, which produce hybrid molecules between the chimaeric protein repressor-galactosidase and the enzyme beta-galactosidase, were constructed. Repressor-galactosidase in which fully active lac repressor is covalently linked to active beta-galactosidase, is an aggregate with a core structure of four beta-galactosidase parts and two peripheral lac repressor dimers. The lac repressor dimers, which are separated by tetrameric beta-galactosidase, retain all the biological activities of tetrameric lac repressor. Substitution of repressor-galactosidase subunits with beta-galactosidase subunits leads to hybrid molecules with y beta-galactosidase subunits aggregated with (4-y) repressor-galactosidase subunits (where y = 1, 2 or 3). A 2:2 hybrid, i.e. a tetrameric beta-galactosidase core with one lac repressor dimer grafted to it, binds at least 100 times less strongly to 32P-labelled lambdaplac DNA than pure lac repressor or repressor-galactosidase. The data suggest a model in which lac repressor binds with two subunits to lac operator and with the other two subunits elsewhere on the DNA, possibly on sequences like the lac operator.
构建了大肠杆菌异源体，其可产生嵌合蛋白阻遏物 - 半乳糖苷酶与β - 半乳糖苷酶之间的杂合分子。完全活性的乳糖阻遏物与活性β - 半乳糖苷酶共价连接的阻遏物 - 半乳糖苷酶，是一种聚集体，其核心结构由四个β - 半乳糖苷酶部分和两个外周乳糖阻遏物二聚体组成。被四聚体β - 半乳糖苷酶隔开的乳糖阻遏物二聚体保留了四聚体乳糖阻遏物的所有生物学活性。用β - 半乳糖苷酶亚基替代阻遏物 - 半乳糖苷酶亚基会产生杂合分子，其中y个β - 半乳糖苷酶亚基与（4 - y）个阻遏物 - 半乳糖苷酶亚基聚集在一起（其中y = 1、2或3）。一种2:2杂合体，即一个嫁接有一个乳糖阻遏物二聚体的四聚体β - 半乳糖苷酶核心，与32P标记的λplac DNA的结合强度比纯乳糖阻遏物或阻遏物 - 半乳糖苷酶至少低100倍。这些数据提示了一个模型，其中乳糖阻遏物用两个亚基与乳糖操纵基因结合，并用另外两个亚基与DNA上的其他位置结合，可能是与类似乳糖操纵基因的序列结合。
