Effects of the movement of insertion sequences on the structure of VanA glycopeptide resistance elements in Enterococcus faecium

A Tn1546-related element with IS1216V at position 8839 underwent a structur al change after storage of the host strain of Enterococcus faecium at 4 deg rees C. The element acquired IS1542 at position 3932, nucleotides 8732 to 8 831 were deleted, and the first 3417 nucleotides were lost and replaced by an inverted copy of the IS1216V-vanY-vanZ-inverted-repeat block from the 3' end. Insertion sequence movement is likely to play a key role in the evolu tion of VanA. resistance elements.