1887

Abstract

Summary: Protection against lethal infections by bacteriophage may seem the most likely role of restriction-modification (R-M) systems in bacteria and the reason for their evolution. There are, however, phenomena which question this phage-mediated selection hypothesis for the maintenance of extant R-M systems. Most prominent among these are the mechanisms phage have to avoid or otherwise limit the effects of the restriction endonucleases produced by their host bacteria. To evaluate the importance of these antirestriction mechanisms in , we have examined the sensitivity of coliphage from natural and laboratory sources to a series of type I and II R-M systems. The results of our study indicate that, , restriction endonucleases have no effect on a substantial fraction of naturally occurring coliphage. The absence of restriction sites appears to be the most common reason why these phage are unaffected by type II restriction endonucleases, but other antirestriction mechanisms also operate. On the other hand, the frequency of naturally occurring coliphage sensitive to restriction appears sufficiently great for phage-mediated selection to be a viable hypothesis for the maintenance of R-M in and its accessory elements.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-139-6-1283
1993-06-01
2019-11-13
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-139-6-1283
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error