Hashiba H, Takiguchi R, Joho K, Aoyama K, Hirota T
Technical Research Institute, Snow Brand Milk Products Co., Ltd., Saitama, Japan.
Biosci Biotechnol Biochem. 1993 Oct;57(10):1646-9. doi: 10.1271/bbb.57.1646.
The replication region of the 2.77-kilobases (kb) plasmid pST1 from Streptococcus thermophilus No. 29 was identified. Deletion derivatives of pST1 were introduced into plasmid-free S. thermophilus No. 29 and examined for their ability to replicate autonomously. The nucleotide sequence had one open reading frame encoded for a 315 amino acid protein (Rep). Comparisons with proteins encoded by other Gram-positive bacterial plasmids strongly suggest that the deduced protein (RepS) encoded by pST1 has a replicative role. pST1 also contains a DNA sequence similar to the origin nick sequences of pLP1 or pLAB1000, which initiate plasmid replication at the plus origin. In a maxicell system, E. coli CSR603 carrying pSTUC4 produced a protein that was considered to correspond to the product of the RepS gene. These results strongly suggest that pST1 is replicated following a rolling-circle mechanism via single-stranded DNA intermediates.
