Sprague K U, Faulds D H, Smith G R
Proc Natl Acad Sci U S A. 1978 Dec;75(12):6182-6. doi: 10.1073/pnas.75.12.6182.
X4+ mutations, responsible for the Chi phenotype in phage lambda, locally increase the rate of recombination promoted by the Escherichia coli recombination system (Rec). X+ mutations in the cII gene, one of a few sites in lambda at which such mutations arise, were located genetically and physically with overlapping deletions. DNA sequence analysis of the deletion segment containing the X+ C mutations showed that two independent X+ C mutations arose by the same A-T to T-A transversion. Presumably, this change creates a nucleotide sequence recognized by a protein involved in a rate-limiting step of recombination.
X4+突变负责噬菌体λ中的Chi表型，它局部提高了大肠杆菌重组系统（Rec）促进的重组率。cII基因中的X+突变是λ中出现此类突变的少数位点之一，通过重叠缺失进行了遗传定位和物理定位。对包含X+C突变的缺失片段进行DNA序列分析表明，两个独立的X+C突变是由相同的A-T到T-A颠换产生的。据推测，这种变化产生了一个由参与重组限速步骤的蛋白质识别的核苷酸序列。
