Froehlich B J, Scott J R
Department of Microbiology and Immunology, Emory University Health Sciences Center, Atlanta, Georgia 30322.
J Bacteriol. 1990 May;172(5):2762-4. doi: 10.1128/jb.172.5.2762-2764.1990.
Miniplasmids with the P1 copN22 mutation have a copy number about seven times that of the wild type. Selection for reduced copy number from this plasmid led to the isolation of second-site pseudorevertants, called poc mutants. DNA sequence analysis showed that all six independent poc mutants have a single base change in the same codon of the repA gene. This implicates the amino acid at this location, either directly or indirectly, in interactions important for copy number control.
带有P1 copN22突变的微型质粒的拷贝数约为野生型的七倍。从该质粒中筛选降低的拷贝数导致了第二位点假回复突变体（称为poc突变体）的分离。DNA序列分析表明，所有六个独立的poc突变体在repA基因的同一密码子中都有一个单碱基变化。这表明该位置的氨基酸直接或间接地参与了对拷贝数控制很重要的相互作用。
