Smith G R, Kunes S M, Schultz D W, Taylor A, Triman K L
Cell. 1981 May;24(2):429-36. doi: 10.1016/0092-8674(81)90333-0.
Chi recombinational hotspots are sites around which the rate of Rec-promoted recombination in bacteriophage lambda is elevated. Examination of a derivative of lambda into which the plasmid pBR322 was inserted reveals that pBR322 lacks Chi sites. Using this lambda-pBR322 hybrid, we obtained mutations creating Chi sites at three widely separated loci within pBR322. Nucleotide sequence analysis reveals that the mutations are single base-pair changes creating the octamer 5' GCTGGTGG 3'. This sequence is present at three previously analyzed Chi sites in lambda, and all analyzed mutations creating or inactivating these Chi sites occur within this octamer. We conclude that Chi is 5' GCTGGTGG 3', or its complement, or both.
Chi重组热点是噬菌体λ中Rec促进的重组率升高的位点周围区域。对插入了质粒pBR322的λ衍生物进行检查发现，pBR322缺乏Chi位点。利用这种λ-pBR322杂种，我们在pBR322内三个相距很远的位点获得了产生Chi位点的突变。核苷酸序列分析表明，这些突变是单碱基对变化，产生了八聚体5' GCTGGTGG 3'。该序列存在于λ中三个先前分析过的Chi位点处，并且所有分析过的产生或使这些Chi位点失活的突变都发生在这个八聚体内。我们得出结论，Chi是5' GCTGGTGG 3'，或其互补序列，或两者皆是。
