Lecture 9 handout.pdf

Micro/Genome 411 Lecture 8 REGULATION OF TRANSPOSITION I. Transposition of composite transposons A. Multiple mobilizable elements B. Mutation of adjacent genes 1. Deletions 2. Inversions II. Regulation of transposition A. Benefits of limiting transposition B. Limiting transposition with low tnp expression (Tn10 / IS10) 1. Safeguarding against external promoters 2. Sequestering translational signals in mRNA C. Limiting transposition with required translational errors (IS1) D. Limiting transposition with low Tnp activity 1. Unstable (protease-sensitive) Tnp (IS903) 2. DAM methylation of terminal repeats (IS10) a. Strand-specific effects of hemi-methylated DNA b. Coupling transposition to replication Replicative transposition of Tn3 TranspositionResolution Genes: cis-acting elements: tnpRtnpAAmp r res Lecture 9: Regulation of Transposition Micro/Genome 411 tnpTet r Tet r tnp Transposon Chromosome Tet Tet Intermolecular transposition of Tn10 : Tet Tet Tet Tet Intramolecular transposition of Tn10 : Tet a b d c ori Tet a b d c ori Tet a b d c ori Tet b a d c ori Tet Tet Intramolecular transposition of Tn10 : Lecture 9: Regulation of Transposition Micro/Genome 411 tnp Tet r Tn10 tnp DNA tnp tnp mRNA (0.25 molecules / generation) Tnp protein (0.6 molecules / mRNA) IS10 Transcription Translation Limiting transposition with low tnp expression: tnp P P Safeguarding against external promoters: ATGRBS Transcription start 1 2 3 4 Transcription start mRNA (tnp promoter) mRNA (external promoter) 12 34 mRNA (external promoter)mRNA (tnp promoter) tnp ? TCG ACG G AAA TCA ? ? Ser Thr Lys Ser IS1 Lecture 9: Regulation of Transposition Micro/Genome 411 tnp IS10 Kendall Gray Microsoft Word - Lecture 9 handout.doc