Jakowec M, Prentki P, Chandler M, Galas D J
Department of Molecular Biology, University of Southern California, Los Angeles 90089-1340.
Genetics. 1988 Sep;120(1):47-55. doi: 10.1093/genetics/120.1.47.
IS1 is one of the smallest transposable elements found in bacteria (768 bp). It contains eight overlapping open-reading-frames (ORFs) greater than 50 codons, designated insA to insG and insB'. To determine which of the ORFs actually code for proteins involved in transposition, we have introduced amber codons into each ORF by site-directed mutagenesis which make neutral changes in the overlapping ORFs. Each mutant IS1 was then tested for its ability to mediate cointegrate formation in Su+ and Su- backgrounds. The mutant elements were also tested for trans-complementation in an IS1-free Salmonella background. Our results show that the products of the insA and insB genes are the only ones essential for cointegrate formation. We suggest that other ORFs may, however, encode accessory proteins.
IS1是在细菌中发现的最小转座元件之一（768个碱基对）。它包含8个重叠的开放阅读框（ORF），长度超过50个密码子，命名为insA至insG以及insB'。为了确定哪些ORF实际上编码参与转座的蛋白质，我们通过定点诱变在每个ORF中引入了琥珀密码子，这些密码子在重叠的ORF中产生中性变化。然后在Su+和Su-背景下测试每个突变型IS1介导共整合体形成的能力。还在无IS1的沙门氏菌背景中测试了突变元件的反式互补作用。我们的结果表明，insA和insB基因的产物是共整合体形成所必需的仅有的蛋白质。然而，我们认为其他ORF可能编码辅助蛋白。
