molecular biology
TRANSCRIPT
Technological
advances let to
identify another link
in the process of
DNA replication
Structures known as
"loops R” perform
replication process in
cells at rest.
In replicating cells, act
various enzymes
Helicase: Breaks
hydrogen bonds
between bases
Forms what is known as
"replication fork"
Both sides of this bind
proteins and maintain the
two DNA strands separate
DNA polymerase adds
new nucleotides to
complement it
DNA breaks in resting cells
• In cells that replicate exists action of enzymes catalyze
different reactions in order to duplicate the genetic
material.
DNA breaks in resting cells
There are two types of genetic material breakage:
• RNA comeback
in the DNA
template
• RNA and DNA
polymerase collide
The system tries to replicate and transcribe
simultaneously
DNA breaks in resting cells
DNA breakage in resting
cells by "Loops R“
• They are precursors of
mutagenesis
• They are much more
active in cellular stress
conditions
I think we should continueresearch on structures thatbreak the DNA and even moreabout mechanisms we can useto inhibit their function,avoiding the appearance ofmultiple alterations.
Missing link:
conformational
changes suffered by
the ORC let starting
the replication
process
The structure ORC
"origin recognition
complex",
commissioned to
identify and bind to
DNA replication sites
Purification,
mixing and
freezing all protein
components
(ORC, replication
indicator, helicase
core)
From these an
intermediate
structure was
rebuilt revealing
unknown
conformational
changes
Photos with cryo-electron microscopy and 3D reconstruction also
demonstrated specific conformational changes
Conformational changes :
The displacement of the ORC facilitates bonding of
the ring-shaped helicase of DNA
Through this study we can
see the importance that it
has know step by step
replication process, so that
we will know that it can be
intervened of many ways
preventing the onset or
progression of some
alteration.
The Knowledge
of the structures
that generate
DNA breaks, its
mechanism of
action and the
place where
acting is very
useful so that in
future we can
prevent their
operationIn the future we can create
devices, mechanisms or drugs to
act on the structures that
generate DNA breakage
Knowledge of the "Loops R" and how they are most active let us to act upon them avoiding the fulfilling its function.
Learning step by step up replication process allows us to make any procedure ensuring that the replication runs its course properly.
The
displacement
of ORC over
by the
helicase let
setting
another point
to intervene in
the replication
process.
MARTINEZ SÁNCHEZ, Lina María. Biología molecular. 7. ed. Medellín: UPB. Fac.de Medicina, 2012. 292p
BCM Scientists unravel mystery behind DNA breaks in resting cells. Bionews Texas. (July 17, 2013)
Key step in molecular DNA duplication deciphered. Bioscience
technology. (July 15, 2013)
THANKS