The interaction between dam methylation sites and Xba1 restriction digest sites in Escherichia coli O157:H7 EDL933

Abstract
Escherichia coli O157:H7 EDL933 (EDL933) has been sequenced. The aim of this study was to gain a better understanding of why the predicted Pulsed-Field Gel Electrophoresis (PFGE) pattern for EDL933, using the restriction enzyme Xba1, differed from that observed in practice. Primers were designed that flanked either side of each of the predicted Xba1 restriction sites and the resultant PCR products were sequenced. No sequencing errors were found in the published genome. The distribution of dam methylation sites within the genome was investigated and a new PFGE pattern was predicted by assuming that any Xba1 restriction site that coincided with a dam methylation site would not be cut. Estimated mean band sizes were obtained from six replicate gels. It was found that the observed and predicted PFGE patterns were in good agreement. The difference between observed and predicted PFGE patterns for EDL933, using Xba1, could be accounted for by assuming that methylated restriction sites were not cut. PFGE is commonly used as a subtyping method. This study provides additional information about the basic technique that could enhance the interpretation of PFGE patterns in comparative studies of E.coli isolates.
Year
2007
Category
Refereed journal
Output Tags
SG 2006-2011 WP 2.2 Control of Bacterial Diseases in Livestock