An IS distribution study among 23 closely related O1:K1 pathogenic E. coli strains showed an average of 9 IS2 copies/genome, as compared to the 41, 17, 4, and 3 copies/genome for IS1, IS4, IS5 and IS30, respectively (Lawrence et al., 1989). IS30 displays pronounced preference for certain target sites (those include its own IRs). Conservative transposition from tandem IS30 repeats -called (IS30)2- gives rise to inverse transposition and cointegrate formation, but also deletions and inversions at high frequencies (Olasz et al., 1993). Two weak promoters are present in IS30: P30A in front of the transposase, and P30C promoting transcription from position 721, on the opposite strand (Dalrymple and Arber, 1985). A "-35" box located in the right IR can create new promoters with adjacent sequences. IS30 also contains one terminator in the middle of the transposase, T30A, and two terminators (T30C and the strong T30D) in the other orientation (Dalrymple and Arber, 1986). The 17 kDa N-terminal transposase fragment shows protection of 26 nt (position 9 to 34) on the upper strand, and 19 nt (position 9 to 27) on the lower strand of both ends (Stalder et al., 1990). IS30 shares 43 % identity (aa) with IS1086, 32 % with IS4351 and 26 % with ORF3 of the Spiroplasma citri virus SpV1-R8A2B. Note that Tn2671 = [IS1a - CmR - SmR - SuR - IS30 - HgR - IS1b]. IS121 (also called IS30.121) is not identical, though very similar to IS30 (M. Malamy, personal communication, 1994).
Note : the sequence was updated according information in the GenBank file : X00792.