The insertion sequences of Anabaena sp. strain PCC 7120 and their effects on its open reading frames.
Anabaena sp. strain PCC 7120, widely studied, has 145 annotated transposase genes that are part of transposable elements called insertion sequences (ISs). To determine the entirety of the ISs, we aligned transposase genes and their flanking regions; identified the ISs' possible terminal inverted repeats, usually flanked by direct repeats; and compared IS-interrupted sequences with homologous sequences. We thereby determined both ends of 87 ISs bearing 110 transposase genes in eight IS families (http://www-is.biotoul.fr/) and in a cluster of unclassified ISs, and of hitherto unknown miniature inverted-repeat transposable elements. Open reading frames were then identified to which ISs contributed and others--some encoding proteins of predictable function, including protein kinases, and restriction endonucleases--that were interrupted by ISs. Anabaena sp. ISs were often more closely related to exogenous than to other endogenous ISs, suggesting that numerous variant ISs were not degraded within PCC 7120 but transferred from without. This observation leads to the expectation that further sequencing projects will extend this and similar analyses. We also propose an adaptive role for poly(A) sequences in ISs.
Wolk
C Peter
CP
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA. wolk@msu.edu
Lechno-Yossef
Sigal
S
Jäger
Karin M
KM
D000595:Amino Acid Sequence; D017033:Anabaena / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001482:Base Composition; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D055029:Inverted Repeat Sequences; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics*; D010802:Phylogeny
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial