CELLULAR DEFENSE AGAINST FATAL ASSOCIATIONS BETWEEN PROTEINS AND

DNA AND DNA “REPLICATION FORK” RECONSTITUTED FOR THE FIRST TIME

Laura Quintero GutiérrezMedical student

3rd semesterMolecular Biology

INTRODUCTION

Through studies made since XIX

century, was possible to discover that

the molecules of DNA are carriers of the

genetic information .

The Chromosomes contents the linear

DNA molecules and they are compound

by histones and DNA molecules.

The DNA needs to be processed and a

very important part of processing is the

replication.

The DNA acquires a tridimensional

structure that can be modified and

causes alterations in the health.

CELLULAR DEFENSE

AGAINST FATAL

ASSOCIATIONS BETWEEN

PROTEINS

AND DNAJuly 3, 2014

NEW 1DNA is very vulnerable to

various types of damages. These

damages can cause the

crosslinking of proteins to DNA

Some types of DNA damages are caused by X rays, Gamma rays, UV

radiations or spontaneous alterations.

Furthermore, the DNA-proteins

cross link interfere with the

replication process.

NEW 1

In the process of replication, one brand of DNA

synthesizes a new one, and then we

will have two daughter brands of DNA. It occurs in S

phase of cellular cycle.

To do the replication, the cells

needs to unwind and separate de DNA double helix

with the topoisomerase and helicase, so these enzymes may be blocked by DPCs

and the cell doesn’t replicate the DNA.

NEW 1

The block of these enzymes is a way to inhibit the replication

and avoid the alterations of DNA,

caused by DNA-proteins crosslink

However, the protease Wss 1 has

the capacity to remove the DNA-

proteins crosslinks, only in presence of

DNA, so the replication can

continue and the damages of DNA will

not affect the replication and the genetic information

The finding of a new

enzyme with these

characteristics is a good

tool to attend diseases

that are caused by

modifications in DNA as

cancer, and to avoid

using aggressive

therapies that

deteriorate the quality of

life of people with

cancer.

NEW 1 OPINION

I think this kind of findings may

improve the knowledge about DNA

processing and therapy of illness.

DNA 'REPLICATION FORK'

RECONSTITUTED FOR

THE FIRST TIMEJULY 9, 2014

NEW 2

The replication is a

fundamental step in the

cycle of cells and it has a

important part: The unzip

of double stranded DNA

and to create a daughter

copies

The replication is a

semiconservative

process, because a

original brand is

conserved in the

daughter brand.

For the replication process the cell needs enzymes as

polymerase DNA, ORI, fork replication, Okazaki fragment.

DNA ligase, helicase, SSDBP, RNAasa H and topoisomerase.

NEW 2

The principal enzyme of replication is the DNApolymerase, it catalyzes the bonds of dNTP tooriginate the DNA strand

• The replication fork is the active region of DNAsynthesis. In this point the strands are separatedand the new daughter brands are synthesized

The new brand are synthesized by polymerase delta and polymerase epsilon. The synthesis of two daughter brands occurs in a discontinuous form. To do this a new primer are needed.

NEW 2

To know in detail how

the process works

O’Donnell brought

essential enzymes,

nucleotides and linear

molecule of duplex

DNA

Then, the found

features of

polymerase

delta and

polymerase

epsilon

Epsilon,

doesn’t attach

very well to

DNA, it

requires CMG

complex

Delta, , binds

very strongly

to the PCNA

clamp (protein

that encircles

DNA)

NEW 2 OPINION

The developing of new tools to

understand the DNA processing is

a big step in the science

It could be the solution and the answer to many

difficult situations in the health field.

To know how really works the DNA

replication, provide to the scientist and doctors more clues

about the treatment or cure

of most aggressive diseases.

MEDICAL UTILITY

The growths often invade

surrounding tissue and

can metastasize to distant

sites.

Cancer is the uncontrolled

growth and spread of

cells. It can affect almost

any part of the body.

MEDICAL UTILITY

Many cancers can be prevented by avoiding exposure to common risk

factors, such as tobacco smoke

In addition, a significant proportion of cancers can be cured, by surgery,

radiotherapy or chemotherapy, especially if they are detected early.

Some people use chemotherapy (chemo) to eliminate cancerous cells, to decrease the symptoms or pain,

but chemo is very aggressive

MEDICAL UTILITY

Chemotherapy is the use of

drugs to kill bacteria, viruses,

fungi, and cancer cells. Most

commonly, the term is used to

refer to cancer-killing

drugs. Chemotherapy drugs

can be given by mouth or

injection. Because the

medicines travel through the

bloodstream to the entire

body, the majority of

administered chemotherapy is

considered a body-wide

(systemic) treatment

MEDICAL UTILITY

However, some normal

cells -- including those

found in the bone

marrow, hair, and the

lining of the

gastrointestinal tract --

also divide very quickly.

Chemotherapy can

also damage or kill

these healthy cells.

The findings of the news

can be a good tools to

avoid the side effects of

chemo, so, the people will

not develop cancer and the

people with cancer will be

right.

BIBLIOGRAPHY

Max-Planck-Gesellschaft. "Cellular defense against fatal associations

between proteins and DNA." ScienceDaily.

www.sciencedaily.com/releases/2014/07/140703142350.htm (accessed

July 19, 2014).

Rockefeller University. "DNA 'replication fork' reconstituted for the first

time." ScienceDaily.

www.sciencedaily.com/releases/2014/07/140709100106.htm (accessed

July 18, 2014)

Perry MC. Approach to the patient with cancer. In: Goldman L, Schafer AI,

eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier;

2011:chap 182.

http://www.nlm.nih.gov/medlineplus/ency/article/002324.htm

World Health Organization, Cancer. http://www.who.int/topics/cancer/en/

MARTINEZ SÁNCHEZ, Lina María. Biología molecular. 7. ed. Medellín:

UPB. Fac. de Medicina, 2012. 78 p.