DISTRIBUTION OF TN551 INSERTION SITES RESPONSIBLE FOR AUXOTROPHY ON THE STAPHYLOCOCCUS-AUREUS CHROMOSOME
DISTRIBUTION OF TN551 INSERTION SITES RESPONSIBLE FOR AUXOTROPHY ON THE STAPHYLOCOCCUS-AUREUS CHROMOSOME
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DOI：
10.1128/jb.145.1.479-488.1981
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发表时间：
1981-01-01
影响因子：
3.2
通讯作者：
PATTEE, PA
中科院分区：
文献类型：
--
作者：
PATTEE, PA
A method was devised to efficiently select isolates of S. aureus 8325 in which Tn551, a transposon originating on the pI258 plasmid and responsible for erythromycin resistance (Emr), had translocated to the host chromosome. This method consisted of selecting for Emr at 43.degree. C with a strain in which the pI258 plasmid was unable to replicate at 43.degree. C because of a temperature-sensitive plasmid mutation. By selecting isolates that were Emr at 43.degree. C and auxotrophic for nutrients not required by the parent strain, Tn551-induced auxotrophic mutants were readily isolated. The incidence of auxotrophic classes was not random; 80% of the isolates in 1 experiment were Trp-, whereas only a single example of each of some of the other classes was isolated. Among the Trp- mutants, the distribution of trp genes affected and the frequency of precise excision of Tn551 from individual sites varied. When analyzed by transformation, the Tn551-induced ala, his, ilv, lys, rib, thrA, thrB and trp mutations were shown to occupy sites previously defined by nitrosoguanidine-induced mutations. Tn551-induced mutagenesis provided three previously unrecognized classes of auxotrophs (tyr met and thrC), and the Tn551 integration sites resulting in these mutations have been identified. A chromosomal region (uraB) was identified by Tn551 mutagenesis that is distinct from uraA (previously defined by chemical mutagenesis). Some Tn551-induced mutations (most notably pur) could not be linked to the known linkage groups of the chromosome by transformation. With the exception of 2 pur mutations, all of the Tn551-induced auxotrophic mutational sites cotransformed at unity with Tn551 and, in cases in which they were selected, prototrophic transformants were always Ems. The Tn551 and auxotrophic sites are identical.
