Molecular Properties of Streptococcus thermophilus Plasmid pER35 Encoding a Restriction Modification System
Autor: | George A. Somkuti, Barbara T. Solow |
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Rok vydání: | 2001 |
Předmět: |
Streptococcus thermophilus
Sequence Homology Amino Acid Molecular Sequence Data Lactococcus lactis Streptococcus food and beverages General Medicine Biology biology.organism_classification Applied Microbiology and Biotechnology Microbiology Bacteriophage Industrial Microbiology Open Reading Frames Plasmid Horizontal gene transfer Food Microbiology bacteria Restriction modification system DNA Restriction-Modification Enzymes Fermentation Amino Acid Sequence Bacteria Plasmids |
Zdroj: | Current Microbiology. 42:122-128 |
ISSN: | 1432-0991 0343-8651 |
Popis: | Bacteriophage attack on lactic fermentation bacteria (LFB) is costly to the dairy industry because it results in product loss. One mechanism used by LFB to protect themselves from bacteriophage attack is restriction of foreign DNA. Three plasmids, pER16, pER35, and pER36, from three different strains of the thermotolerant dairy fermentation bacterium Streptococcus thermophilus were sequenced. One of these plasmids, pER35, isolated from S. thermophilus ST135, encoded a type IC restriction-modification (R-M) system very similar to those encoded on plasmids pIL2614 in Lactococcus lactis subsp. lactis and pND861 in Lactococcus lactis biovar diacetylactis. The high degree of identity between the R-M systems encoded on pER35, pIL2614, and pND861 indicated the potential for horizontal transfer of these genes between different species of lactic fermentation bacteria. Similar to the functional R-M system encoded on pIL2614 that protects the mesophilic L. lactis subsp. lactis against phage attack, the R-M system on pER35 most likely functions in the same role in S. thermophilus ST135. The plasmid pER16 was found to encode the specificity subunit of the R-M system, but not the R or M subunits. In addition, all three plasmids encoded proteins that are present on other S. thermophilus plasmids, including a protein for rolling-circle replication (RepA) and a low-molecular-weight stress protein (Hsp). The presence of a complete R-M system encoded on a plasmid in S. thermophilus, a species that often lacks plasmids, is novel and may be beneficial for protecting S. thermophilus from bacteriophage attack under dairy fermentation conditions. |
Databáze: | OpenAIRE |
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