Brcić-Kostić K, Stojiljković I, Salaj-Smic E, Trgovcević Z
Institute Ruder Bosković, Zagreb, Croatia, Yugoslavia.
Mutat Res. 1989 Dec;227(4):247-50. doi: 10.1016/0165-7992(89)90105-x.
The recB21 mutation abolishes the exonuclease activity of the RecBCD enzyme (exonuclease V) of Escherichia coli. This might be due to the polar effect of recB21 on expression of the recD gene, the product of which is an essential component of the RecBCD enzyme. To achieve synthesis of the recD gene product, the recD+ plasmid was introduced into the recB21 mutant. Degradation of the endogenous DNA damaged by gamma-rays and degradation of the DNA of a phage T4 gene 2 mutant were nevertheless abnormally small in this strain. Thus, the functional recB gene product is required for the degradative function of the RecBCD enzyme.
recB21突变消除了大肠杆菌RecBCD酶（外切核酸酶V）的外切核酸酶活性。这可能是由于recB21对recD基因表达的极性效应，recD基因的产物是RecBCD酶的一个必需组分。为了实现recD基因产物的合成，将recD⁺质粒导入recB21突变体中。然而，在该菌株中，受γ射线损伤的内源DNA的降解以及噬菌体T4基因2突变体的DNA的降解异常少。因此，功能性recB基因产物是RecBCD酶降解功能所必需的。
