Its all about transposable elements..

2. Mobile DNA sequences
Cause mutations in adjacent genes
Cause chromosomal rearrangements
Relocate genes

3. The RNA virus
Convert its sequence into
DNA by Reverse transcriptase
Infectious
PROVIRUS:
A duplex DNA seq.
Integrated into eukaryotic
genome
Represent RNA seq. of
Retrovirus
RETROTRANSPOSONS:
generate nucleoprotein
capsids but no mature virus
particles are formed
Do not undergo an
extracellular phase

4. Flanking direct
repeats( 3 t0 12bp)
Terminal inverted
repeats(9 to 40bp)
Transposase enzyme
Resolvase enzyme
Special genes:
Antibiotic resistance
EX. KANR ,TETR

5. R U5 U3 R

6. CLASS 1: DNA TYPE ELEMENTS CLASS 2: RETROELEMENTS
TRANSPOSITION BY: DNA INTERMEDIATE
TRANSPOSEWITHIN GENOME
TRANSPOSITION BY: RNA INTERMEDIATE
TRANSPOSE BETWEEN GENOMES
MAY CAUSE MUTATION MAY COUSE INFECTION
MAY OR MAY NOT SHOW PHENOTYPIC
CHANGE
MAY ALTER THE PROPERTIES OF THE INFECTED
CELL
CELLULAR SEQUENCES CAN RECOMBINE
WITH TE BUT CAN NOT BE TRANSDUSED
CELLULAR SEQUENCES RECOMBINE WITH
RETROVIRAL SEQUENCES AND TRANSDUSED
PRESENT IN BOTH PROKARYOTES AND
EUKARYOTES
PRESENT ONLY IN EUKARYOTES
GENES ENCODED: TRANSPOSASE ,
RESOLVASE AND SOMETIMES SPECIAL GENES
GENES ENCODE: REVERSE TRANSCRIPTASE,
INTEGRASE

7. CLASS 1: DNA TYPE ELEMENTS CLASS 2: RETROELEMENTS
BACTERIAL
TRANSPOSONS
EUKARYOTIC
TRANSPOSONS
RETROTRANSPOSONS RETROPOSONS
ABUNDANT
CARRY GENES
REQUIRED FOR ITS
OWN TRANSPOSITION
GENERAL
ORGENIZATION:
TERMINAL INVERTED
REPETS, FLANKING
DIRECT REPETES,
TRANSPOSASE GENE
NOT WELL
CHARACTERIZED
BUT CAMPARABLE
SYSTEMS ARE
PRESENT
GENERAL
ORGANIZATION:
TERMINAL INVERTED
REPETS, FLANKING
DIRECT REPETES,
TRANSPOSASE GENE
LTR TRANSPOSONS
CLOSELY RELETED TO
RETROVIRUSES
SOURCE OF
MOBILITY:
DNARNADNA
TERMINAL REPEATS:
4-6bp
MAY CAONTAINS
INTRONS( REMOVED
IN SUBGENOMIC
mRNA)
NON-LTR
TRANSPOSONS
SOURCE OF
MOBILITY:
RNA INTERMEDIATE
TERMINAL REPEATS:
7-21bp
CONTAINS ONE OR
TWO UNINERRUPTED
ORFs
EXAMPLES:
IS ELEMENTS
Tn ELEMENTS
EXAMPLES:
Ac/Ds ELEMETS
P ELEMTS
EXAMPLES:
Ty1
copia
EXAMPLES:
F, G, I ELEMENTS
LINES AND SINES

8. The movement of a transposable element from one location
to another
All types of transposition have several features in common:
(1) staggered breaks are made in the target DNA
(2) The transposable element is joined to single-stranded
ends of the target DNA
(3) DNA is replicated at the single strand gaps

9. Transposable elements Retroelements
mRNA

13. PROPERTIES BACTERIAL TRANSPOSASE RETROVIRAL INTERGASASE
INSERTION EVENT CHEMICALLY IDENTICAL
SEQUENCE SIMILARITY CERTAIN AMINO ACIDS ARE SIMILER IN BOTH ENZYMES AT THE
ACTIVE SITE CALLED, DDE MOTIF
END RECOGNITION SEQUENCE SELECTIVITY IN
BINDING
LITTLE OR NO SEQUENCE
SELECTIVITY IN BINDING
STRAND CLEVAGE CAN CLEAVE SINGLE STRAND
OR DOUBLE STRAND OR CAN
CREATE INTERMEDIATES
CARRYING OVERHANGS
ONLY CLEAVES SINGLE STRAND
STRAND TRANSFER THE TERMINAL SEQUENCES
MAY OR MAY NOT INFLUENCE
THE STRAND TRANSFER
THE TERMINAL NUCLEATIDES,
WHICH ARE ELIMINATED IN
THE INTEGRATED PROVIRUS
INFLUENCE THE STRAND
TRANSFER
Polard &Chandle’ Bacterialtransposases and retroviral integrases’, Molecular Microbiology (1995) 15(1), 13-23

14. Insertion sequences
Carries only the genetic information necessary for its
movement
Constituents of bacteria and plasmids
800 to 2000 bp
Cut-and-paste transposons
Terminal inverted repeats
The generation of flanking direct repeats at the site of
insertion

15. Composite transposons
Any segment of DNA that becomes flanked by two copies
of an insertion sequence may itself transpose and is called a
composite transposon.
Terminal inverted repeats
Generate flanking direct repeats at their sites of insertion

16. Noncomposite transposons
lack insertion sequences
5000 bp long
Terminal inverted repeats of 38 bp
Generates flanking direct repeats of5 bp
Carries genes for transposase and resolvase plus a gene
that codes for the enzyme -lactamase, which provides
resistance to ampicillin.

17. Transposing bacteriophages
Generate short (5-bp) flanking direct repeats
Mu replicates through transposition
Like the TE they causes mutations at the site of insertion

19. Variation at sub genomic level:
Variation mediated by excisions and transposes-mediated
deletions
Variations mediated by insertions
Sterility associated with hybrid dysgenesis
Variation at genomic level:
Non random distribution and genome partitioning
TE and genome size
Transposons induced variation and host evolution
Germline restriction of transposition
Host responses: epigentic regulation of TE

20.  Transposable elements may create genetic diversity
 Act as promoters
 Allow recombination between plasmid and genomic DNA
when multiple copies of the element are present
 Carry antibiotic resistance genes, conferring an
advantage on bacterial cells
 Increase the number of copies of an exon or gene

21. Gene tagging
Transposon traps
Chromosomal rearrengements
Activation tagging
Reverse genetic screening
Retroviral vectors are useful for animal transformation
Insertional Mutagenesis for Gene Identification
Vector Insertion as a Marker for Gene Activity during
Development
Transfer of Genes That Regulate Development in Animals
Chromosome Tagging
Shuttle Vectors
Cellular Immortalization

22. BOOKS
1.Genetics A conceptual Approach (2nd edition)
Benjamin Pierce
2.Lewin’s essential GENES (3rd edition)
J.Krebs, E.Goldstein, S.Kilpatrick
3.Mobile DNA 2
Edited by: N.Cradig, R.Craigie, M.Gellert, A.Lambowitz
RESEARCH PAPERS
1.C. Kumar, K. Narayana ‘Plant transposable elements and functional genomics’,
Plant Biotechnology(1998) 15(4), 159-165
2.P.Polard , M.Chandler ‘Bacterial transposases and retroviral integrases’
Molecular Microbiology(1995) 15(1),13-23
3. P.Rice , T.Baker ‘Comparative architecture of transposase and integrase
complexes’nature structural biology ,Volume 8 number 4 ,April 2001
4. Martín Muñoz-López and José L. García-Pérez ‘DNA Transposons: Nature and
Applications in Genomics’ Current Genomics, 2010, 11, 115-128
5. C. Feschotte,N. Jiang and S.Wessler,’ Plant transposable elements:where genetics
meets genomics’ Nature Reviews ,Genetics,volume 3 ,may 2002 ,329-341
6. A D Miller ‘Development and Applications of Retroviral Vectors’
www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf