Transposone And Retrotransposone

[object Object],Presented by: Salar Bakhtiyari

They are discrete sequence in the genome that are mobile they are able to transport themselves to other location. Other names: ,[object Object],[object Object],[object Object],[object Object],TEs are present in the genome all species of three domains Transposable Elements

What do we want to know about mobile genetics elements? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Why study mobile genetic elements? ,[object Object],[object Object],[object Object]

The discovery of mobile genetic elements ,[object Object],[object Object],[object Object]

The discovery of transposable elements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Barbara Mc Clintock 1902  1980 ( noble in 1984)

Plasmid , phage ,[object Object],[object Object],[object Object],[object Object],[object Object]

Classification of transposable elements ,[object Object],[object Object]

Autonomous and non autonomous elements ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

DNA based elements ,[object Object],[object Object],[object Object],[object Object],[object Object]

Composite transposone ,[object Object],[object Object],IS modules - identical (both functional: Tn9; Tn903) or closely related (differ in functional ability: Tn10; Tn5) 1. A functional IS module can transpose either itself or the entire transposon

Mechanism of transposition ,[object Object],[object Object],Direct repeats are generated by introduction of staggered cuts whose protruding ends are linked to the transposon .

Mechanism of transposition 1- Replicative transpositon ,[object Object],[object Object],[object Object],[object Object]

Mechanism of transposition 2 - Nonreplicative ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],Donor cut 1. Synapsis stage - two ends of transposon are brought together 3. . Nicked ends joine crosswise;covalent connection between the transposon the target 2. Transposon nicked at both ends; target nicked at both strands

cuts in trans transfers in trans 22 bp Mu integrates by nonreplicative transposition; during lytic cycle- number of copies amplified by replicative transposition - MuA binds to ends as tetramer forming a synapsis . - MuA subunits act in trans to cut next to R1 and L1 (coordinately; two active sites to manipulate DNA). - MuA acts in trans to cut the target site DNA and mediate in trans strand transfer

The chemistry of Donor and target cut The 3’-ends ends groups released from flanking DNA by donor cut reaction They are nuclophile that attack phosphodiester bonds in target DNA ,[object Object],3 ‘ OH 3 ‘ OH 3 ‘ OH 3 ‘ OH ,[object Object]

[object Object],[object Object],[object Object],[object Object],transposon target Strand transfer complex

Molecular mechanism of transposition (I) Replicative transposition Replicative transposition proceeds through a cointegrate . Transposition may fuse a donor and recipient replicon into a cointegrate. Resolution releases two replicons-each has copy of the transposon

Replicative transposition Ligation to target ends 3. 3’-ends prime replication The crossover structure contains a single stranded region at each of the staggered ends= pseudoreplication forks that provide template for DNA synthesis Donor and target cut cointegrate .

Non-replicative Replicative additional nicking common structure Breakage & reunion

Retrotransposon ( retroposons ) ,[object Object],[object Object],[object Object],[object Object]

Types of Retrotransposons ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],non LTR- retrotransposon

retrovirus RNA reverstranscriptase Liner DNA Integration provirus Transcription RNA

LTR - retrotrasposon pol Reverse transcriptase (RT) Integrase (IN) Ribonuclease H (RH) gag env ?

mechanism of transposition Integrase acts on both the retrotransposon line DNA and target DNA ,[object Object],[object Object],[object Object],[object Object],3’-ends 5’-ends

Non – LTR retrovirus ,[object Object],[object Object],[object Object],[object Object]

Effect of transposabli elements on gene and genome ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Modification of gene expression ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Alternation gene sequence ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Chromosomal structural changes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Use as strain specific diagnostic tools ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Use of TEs as molecular tools

Use of TEs as molecular tools ,[object Object],[object Object],[object Object],[object Object],Tools for the analysis of population structure

Gene tagging with transposable elements ,[object Object],[object Object],Use of TEs as molecular tools ,[object Object],Target gene can easily determined by PCR methods

Transposone And Retrotransposone

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