molecular biology

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