Transposable elements (TEs), also known as "jumping genes" or transposons, are sequences of DNA OR Mobile DNA elements that move (or jump) from one location in the genome to another. They are also known as jumping gene.

1. TRANSPOSABLE
ELEMENTS
S U B M I T T E D T O : D R . S N E H A M A C WA N A
A S S O C I AT E P R O F E S S O R
D E PA R T M E N T O F G E N E T I C S A N D P L A N T
B R E E D I N G
B . A . C . A , A . A . U , A N A N D
S U B M I T T E D B Y : M AY U R K U M A R S O N A G A R A
R E G N O . - 0 4 - 3 0 9 5 - 2 0 1 7
S U B - G P 5 0 1
B . A . C . A , A . A . U , A N A N D

2. INTRODUCTION
• Transposable elements (TEs), also known as "jumping genes" or transposons,
are sequences of DNA OR Mobile DNA elements that move (or jump) from
one location in the genome to another. They are also known as jumping gene.
• Transposable elements make up a large fraction of the genome and are
responsible for much of the mass of DNA in a eukaryotic cell. It has been
shown that TEs are important in genome function and evolution. Transposons
are also very useful to researchers as a means to alter DNA inside a living
organism.
• Term TRANSPOSON was given by “Hedges and Jacob(1947).

3. • Mobile genetic elements”
• Comprise 45% of human chromosomal DNA “middle repetitive DNA”
• Contribute to spontaneous mutation, genetic rearrangements, horizontal transfer
of genetic material
• Aid speciation and genomic change (in bacteria transposons are often
associated with antibiotic resistance genes)
• Cells must depress transposition to insure genetic stability

4. • Normal and ubiquitous components of prokaryote and eukaryote genomes.
• Prokaryotes-transpose to/from cell’s chromosome, plasmid, or a phage
chromosome.
• Eukaryotes-transpose to/from same or a different chromosome.
• Transposable elements cause genetics changes and make important contributions to the
evolution of genomes:
• Insert into genes.
• Insert into regulatory sequences; modify gene expression.
• Produce chromosomal mutations.

5. DISCOVERY OF TRANSPOSONS
• Barbara McClintock 1950’s Ac Ds system in maize influencing
kernel color
unstable elements
changing map position
promote chromosomal breaks
• Barbara discovered transpososons in maize in 1948 and
received noble price in 1983.
Barbara McClintock 1902-1992

6. CLASSIFICATION
CATEGORY EXAMPLE HOST/ORGANISM
1. CUT AND PASTE
TRANSPOSOND
IS ELEMENETS Bacteria
Ac/Ds elements Maize
P elements Drosophila
2.COPY AND PASTE
TRANSPOSONS
Tn3 elements Bacteria
3.RETROPOSONS F,G and I elements Drosophila
LINES and SINES Human
4.RETRO VIRUS LIKE
ELEMENTS
Ty1 Yeast
Copia and Gypsy Drosophila

7. TRANSPOSABLE ELEMENTS
VIRAL TRANSPOSON NON VIRAL TRANSPOSON BACTERIAL TRANSPOSON
(LTR ELEMENTS) NON-LTR IS ELEMENTS
1.Retroviral 1.LINES(Long-Interspersed
Sequences)
1.Bacteria
2.Drosophila- Copia 2.SINES(Short-Interspersed
Sequences)
2.Drosophila- Pele
3.Yeast- Ty1 3.Corn- Ac/Ds

8. TRANSPOSONS IN PROKARYOTES
• This are transposons that occur within Bacterial chromosome or between
bacterial chromosome and plasmid. There are three types of transposons in
prokaryotes namely
1. INSERTIONAL SEQUENCE
2. COMPOSITE TRANSPOSONS
3. Tn3 ELEMENTS

9. 1.INSERTIONAL SEQUENCE
It is a cut and paste transposon. An insertion sequence (also known as an IS,
an insertion sequence element, or an IS element) is a
short DNA sequence that acts as a simple transposable element.
 Insertion sequences have two major characteristics:
1. They are small relative to other transposable elements (generally around
700 to 2500 bp in length)
2. Only code for proteins implicated in the transposition activity (they are
thus different from other transposons, which also carry accessory genes
such as antibiotic resistance genes).
Duplication occur at the site of the insertion, which is about 2-13 nucleotide long
called TARGET SITE DUPLICATION.

10.  These proteins are usually the transposase which catalyses the enzymatic
reaction allowing the IS to move, and also one regulatory protein which either
stimulates or inhibits the transposition activity.
The coding region in an insertion sequence is usually flanked by inverted
repeats.
 For example, the well-known IS911 (1250 bp) is flanked by two 36bp inverted
repeat extremities and the coding region has two genes partially
overlapping orfA and orfAB, coding the transposase (OrfAB) and a regulatory
protein (OrfA).
They cause mutations which may revert back to wild type.
They bring recombination between F plasmid and bacterial chromosome and
facilities conjugation.
They cause mutations and create variability and also cause evolutionary changes
in bacterial population.
 A particular insertion sequence may be named according to the form ISn,
where n is a number (e.g. IS1, IS2, IS3, IS10, IS50, IS911, IS26 etc.); this is not the
only naming scheme used, however. Although insertion sequences are usually
discussed in the context of prokaryotic genomes, certain eukaryotic DNA

11. 2.COMPOSITE TRANSPOSONS
A composite transposon is similar in function to simple transposons and Insertion
Sequence (IS) elements in that it has protein coding DNA segments flanked by inverted,
repeated sequences that can be recognized by transposase enzymes.
EXAMPLES: Tn9, Tn5, Tn10.
A composite transposon, however, is flanked by two separate IS elements which may or
may not be exact replicas. Instead of each IS element moving separately, the entire
length of DNA spanning from one IS element to the other is transposed as one complete
unit. Composite transposons will also often carry one or more genes conferring
antibiotic resistance.
• It Carry genes (example might be a gene for antibiotic resistance) flanked on both sides
by IS elements.
• Tn10 is 9.3 kb and includes 6.5 kb of central DNA (includes a gene for tetracycline
resistance) and 1.4 kb inverted IS elements.

12. They follow cut and paste mechanism.
They are formed when two IS elements inserted near to each other.
The flanking sequence of IS elements confer resistance to antibiotics
but they have nothing to do with transposition.
In Tn9, IS elements are in same orientation whereas in Tn5 and Tn10 the
IS elements orientation is reversed.

13. 3. NONCOMPOSITE TRANSPOSONS (TN)
TN3 ELEMENTS
Carry genes (example might be a gene
for antibiotic resistance) but do not
terminate with IS elements.
Ends are non-IS element repeated
sequences.
Tn3 follows copy and paste (replicative)
mechanism.

14. They do not have IS elements at their ends but contains inverted
repeats at their terminal regions.
They causes target site duplication.
They contain genes transposase and antibiotic resistance.
Tn3 is 5 kb with 38-bp ITRs and includes 3 genes; bla (-lactamase),
tnpA (transposase), and tnpB (resolvase, which functions in
recombination).

15. • Many bacterial transposons carry genes for antibiotic resistance.
• It is relatively simple matter for these genes to move from one DNA
molecule to another- for instance, from a chromosome to a plasmid.
This genetic flux has a profound medical significance because many of
the DNA molecules that acquire resistance genes can be passed on to
other cells.
• This process has occurred in several species pathogenic to humans,
including strains of Staphylococcus, Neisseria, Sbigella & Salmonella.
• Many bacterial infections causing diseases such as dysentery,
tuberculosis, & gonorrhea are difficult to treat.

16. • The spread of multiple drug resistance in bacterial populations has been
accelerated by evolution of conjugative R plasmids that carry the
resistance genes .
• These plasmids have two components- one called the resistance
transfer factor , or RTF, contains the genes for conjugative transfer
between cells, the other, called the R-determent, contains the genes for
antibiotic resistance.
• These can be passed from one species to another, even between quite
dissimilar cell types-for e.g between a coccus and a bacillus.
• Thus, once multiple drug resistance has evolved in a part of the
microbial kingdom, it can spread to other parts with relative ease.

17. TRANSPOSONS IN EUKARYOTES
Cut and Paste transposition in eukaryotes.
Generally these transposons will have inverted repeats at terminal sites which
will create target site duplications when they inserted into DNA molecules.
Eg., AC/Ds elements in Maize,
‘P’ Elements in Drosophila.
LINES and SINES in Human.

18. AC/DS (ACTIVATOR/DISSOCIATION)
TRANSPOSABLE ELEMENT
The Ac/Ds transposable element system was the
first transposable element system recognized
Its discovery was based on studying its genetic
behavior(striping and spotting of maize kernels
due to chromosomal breakage of chromosome no. 9)
, i.e., "jumping genes" in maize and published
by Barbara McClintock, leading to her 1983 Nobel
in Medicine.
They were called as CONTROLLING ELEMNTS by
Barbara McClintock.
The phenotypic consequence of Ac/Ds transposable
element includes mosaic colors in kernels and leaves

19. Ac (Activator) and Ds (Dissociation) elements are structurally related and move
from one site and get inserted into another site.
When the insertion takes place in or near a gene, gene function is altered i.e. they
cause mutations by inserting into genes.
Ac elements (Autonomous Elements): They encode for transposase enzyme
essential for transpositions and also contain 11 nucleotide base pair long inverted
repeats.
Ds elements (Non-autonomous elements): They are responsible for causing
breakage in chromosome and act only in the presence of Ac elements. They also
contain inverted repeats similar to that of Ac elements.

20. • Their movement depends on the reverse transcription of RNA into DNA.
• The enzyme reverse transcriptase uses RNA as template to synthesize DNA molecules, the
process is called retrotransposition.
• There are two main classes:-
1) Viral retrotransposons / Retro virus-like elements/ LTR retrotransposons
e.g., Ty1 elements( in Yeast )
Copia elements (in Drosophila)
gypsy elements ( in Drosophila)
2) Non-viral retrotransposons/ Retroposons
e.g., LINEs (L1) in Humans
SINEs (Alu) in Humans

21. ‘P’ ELEMENTS IN DROSOPHILA
P elements are transposable elements that were
discovered in Drosophila as the causative agents of
genetic traits called hybrid dysgenesis. The transposon
is responsible for P trait of P element and it is found
only in wild flies.
 Hybrid Dysgenesis: Hybrid dysgenesis refers to the
high rate of mutation in germ line cells
of Drosophila strains resulting from a cross of males
with autonomous P elements (P Strain/P cytotype) and
females that lack P elements (M Strain/M cytotype).
The hybrid dysgenesis syndrome is marked by
temperature-dependent sterility, elevated mutation
rates, and increased chromosome rearrangement and
recombination.

22.  Margaret and James Kidwell studied ‘P’
ELMENTS AND HYBRID DYSGENERIS
in drosophila.
When crosses made between ‘M’ strain as
female parent and ‘P’ strain as male parent,
resulting F1 population show chromosomal
breakage, mutations and sterility, this occurs
only when P strain is used as male parent.
Certain elements present in ‘P’ strains in
Drosophila causes frequent chromosomal
breakage, mutations and sterility in F1
population are known as P elements. These
Present only in P strain of drosophila.
P elements carry gene that encode
transposase enzyme.

23. TRANSPOSABLE ELEMENTS IN
HUMAN
45% of Human genome consists of Transposable elements.
Of these, 98% are Retrotransposons. They are :
1. LINEs (Long Interspersed Nuclear Elements)
2. SINEs (Short Interspersed Nuclear Elements)

24. LINES
Represents 17% of human genome.
LINEs are retrotranspositionally active elements.
The most predominant transposable elements.
 L1 LINE family are most commonly in human genome.
 They are approximately 6kb in length.
 The consensus sequence contains 2 large Open Reading Frames
• ORF1 encodes an RNA binding protein.
• ORF2 encodes protein having both endonuclease and
reverse transcriptase activity.
Complete L1 elements are transcriptionally active where as
incomplete one are inactive. E.g., L1,L2 and L3 elements in human.

25. SINES
These represent 11% of human genome
• SINES are dependent on LINES for retrotransposition.
• These are 100 to 400bp long and do not code for any protein by
LINES.
• It depends on LINES for their multiplication and insertion i.e.
reverse transcriptase needed for DNA synthesis is provided
• Most common SINES in human genome are Alu elements
• Alu are 300bp long and 1 million copies per cell are present.

26. EFFECTS CAUSED BY
TRANSPOSONS
I. Transposons are mutagens hence they cause mutations.
II. They can destroy or alter the gene activity.
III. They are responsible for some mutations which cause diseases
like :
a. Hemophilia A, Hemophilia B.
b. X-linked severe combined immunodeficiency
c. Porphyria
d. Cancer
e. Duchene Muscular Dystrophy

27. USES OF TRANSPOSONS.
• As cloning vehicles
• Transformation vectors for transferring genes between organisms.
• Insertional mutagenesis
• Use of transposons to increase rate of mutation due to
insertional inactivation
• Gene Silencing
• Transposon Tagging
• Gene Therapy

28. Thanks to transposons & ALL OF
YOU