Nastri H G, Knight K L
Department of Biochemistry and Molecular Biology, University of Massachusetts Medical Center, Worcester 01655.
J Biol Chem. 1994 Oct 21;269(42):26311-22.
Using a combinatorial cassette mutagenesis procedure we have introduced a large number of single and multiple amino acid substitutions into an area of the RecA protein defined by residues 152-159. This sequence overlaps the disordered loop 1 region (L1) in the RecA crystal structure which has been hypothesized to be involved in DNA binding. Assays for recombinational DNA repair and LexA coprotease activities identify Glu154 as the only one of these 8 residues which is critical to RecA function. Several other mutations observed at nearby residues support the identity of Glu154 as the most important of the 14 residues in the area defined by Pro151 to Met164. In addition, Gly157 and Glu158 appear to be hot spots for the occurrence of mutation-induced constitutive coprotease activity.
我们使用组合盒式诱变程序，在RecA蛋白由152 - 159位残基定义的区域引入了大量单氨基酸和多氨基酸替换。该序列与RecA晶体结构中无序的环1区域（L1）重叠，据推测该区域参与DNA结合。重组DNA修复和LexA共蛋白酶活性测定表明，Glu154是这8个残基中唯一对RecA功能至关重要的残基。在附近残基处观察到的其他几个突变支持了Glu154作为Pro151至Met164所定义区域中14个残基里最重要残基的身份。此外，Gly157和Glu158似乎是突变诱导的组成型共蛋白酶活性发生的热点。
