In the process of characterizing the Ac element present in the bz-s:2114(Ac) allele, we have discovered two mistakes in the published Ac sequence (R.F. Pohlman, N.V. Fedoroff and J. Messing, Cell 37:635, 1984; M. Mueller-Neumann, J. I. Yoder and P. Starlinger, Mol. Gen. Genet. 198:19, 1984). bz-s:2114(Ac) is a derivative of bz-m-9(Ac), which has a deletion adjacent to Ac (H. Dooner, Plant Genetics, p. 561, 1985). We have cloned both alleles and in restriction mapping we found an MluI site that was not predicted by the published sequence. The site was also present in bz-m2(Ac) and wx-m7(Ac) (pJAC, kindly supplied by J. I. Yoder and P. Starlinger). BamHI-MluI fragments from bz-s:2114(Ac), bz-m2(Ac) and wx-m7(Ac) were filled in with Klenow, subcloned into M13mp18 in both orientations and sequenced. This sequencing confirmed that the MluI site in all three Acs resulted from an additional A residue at base pair (bp) 4132. We also found an additional C residue at bp 4225. The additional A residue at 4132 alters ORF 3 by making it 9 bp (three codons) longer, terminating at 4202. Between this and other work (H. Dooner, J. English, E. Ralston, and E. Weck, 1986, Science 234:210), we have sequenced 2300 bp of Ac (see figure) and have confirmed all but the two missed nucleotides described above. With the addition of two base pairs, the length of Ac is at least 4565 bp.
James English, Edward Ralston and Hugo Dooner
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