Gene expression in the DpnI and DpnII restriction enzyme systems of Streptococcus pneumoniae
Although a number of bacterial species are naturally transformable, that is, their cells are able to take up external DNA in substantial amounts and integrate it into the chromosome without artificial manipulation of the cell surface, Streptococcus pneumoniae, the first species in which this phenomenon was detected, remains a prototype of such transformation. Cells of S. pneumonias also contain potent restriction endonucleases able to severely restrict DNA introduced during viral infection. Our current understanding of the genetic basis of the complementary DpnI and DpnII restriction systems and of the biochemistry of their component enzymes are briefly reviewed. The manner in which these enzymes impinge on the transfer of chromosomal genes and of plasmeds will be examined in detail. It will be seen that far from acting against foreign DNA in general, the restriction systems seem to be designed to exclude only infecting viral DNA The presence of complementary restriction systems in different cells of S. pneumonias enhances their effectiveness in blocking viral infection and promoting species survival. This enhanced effectiveness requires the expression of alternative restriction systems. Therefore, the ability of the cells to transfer the restriction enzyme genes and to regulate their expression are important for survival of the species.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10192790
- Report Number(s):
- BNL-49412; CONF-9208242-1; ON: DE93041152
- Resource Relation:
- Conference: 11. European meeting on genetic transformation, DNA transfer and gene expression in microorganisms,Budapest (Hungary),23-27 Aug 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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