Maine G T, Sinha P, Tye B K
Genetics. 1984 Mar;106(3):365-85. doi: 10.1093/genetics/106.3.365.
We have isolated yeast mutants that are defective in the maintenance of circular minichromosomes. The minichromosomes are mitotically stable plasmids, each of which contains a different ARS (autonomously replicating sequence), a centrometeric sequence, CEN5, and two yeast genes, LEU2 and URA3. Forty minichromosome maintenance-defective (Mcm-) mutants were characterized. They constitute 16 complementation groups. These mutants can be divided into two classes, specific and nonspecific, by their differential ability to maintain minichromosomes with different ARSs. The specific class of mutants is defective only in the maintenance of minichromosomes that carry a particular group of ARSs irrespective of the centromeric sequence present. The nonspecific class of mutants is defective in the maintenance of all minichromosomes tested irrespective of the ARS or centromeric sequence present. The specific class may include mutants that do not initiate DNA replication effectively at specific ARSs present on the minichromosomes; the nonspecific class may include mutants that are affected in the segregation and/or replication of circular plasmids in general.
我们分离出了在环状小染色体维持方面存在缺陷的酵母突变体。这些小染色体是有丝分裂稳定的质粒，每个质粒都包含一个不同的自主复制序列（ARS）、一个着丝粒序列CEN5以及两个酵母基因LEU2和URA3。对40个小染色体维持缺陷（Mcm-）突变体进行了表征。它们构成了16个互补群。根据这些突变体维持带有不同ARS的小染色体的差异能力，可将它们分为两类，即特异性和非特异性。特异性突变体类别仅在维持携带特定一组ARS的小染色体时存在缺陷，而不考虑所存在的着丝粒序列。非特异性突变体类别在维持所有测试的小染色体时均存在缺陷，而不考虑所存在的ARS或着丝粒序列。特异性类别可能包括那些在小染色体上存在的特定ARS处不能有效起始DNA复制的突变体；非特异性类别可能包括那些总体上在环状质粒的分离和/或复制中受到影响的突变体。
