Checked content

File:DNA Repair.jpg

Summary

Description DNA damage, due to environmental factors and normal metabolic processes inside the cell, occurs at a rate of 1,000 to 1,000,000 molecular lesions per cell per day. A special enzyme, DNA ligase (shown here in colour), encircles the double helix to repair a broken strand of DNA. DNA ligase is responsible for repairing the millions of DNA breaks generated during the normal course of a cell's life. Without molecules that can mend such breaks, cells can malfunction, die, or become cancerous. DNA ligases catalyse the crucial step of joining breaks in duplex DNA during DNA repair, replication and recombination, and require either Adenosine triphosphate (ATP) or Nicotinamide adenine dinucleotide (NAD+) as a cofactor.

Shown here is DNA ligase I repairing chromosomal damage. The three visable protein structures are:

  1. The DNA binding domain (DBD) which is bound to the DNA minor groove both upstream and downstream of the damaged area.
  2. The OB-fold domain (OBD) unwinds the DNA slightly over a span of six base pairs and is generally involved in nucleic acid binding.
  3. The Adenylation domain (AdD) contains enzymatically active residues that join the broken nucleotides together by catalyzing the formation of a phosphodiester bond between a phosphate and hydroxyl group.
It is likely that all mammalian DNA ligases (Ligases I, III, and IV) have a similar ring-shaped architecture and are able to recognize DNA in a similar manner. (See: Nature Article 2004, PDF)
Date 21 November 2006
Source Biomedical Beat National Institute of General Medical Science (NIGMS) Cool Image Gallery
Author Courtesy of Tom Ellenberger, Washington University School of Medicine in St. Louis.
Permission
( Reusing this file)

"The material in this newsletter is not copyrighted and we encourage its use or reprinting."

Licensing

Public domain This work is in the public domain in the United States because it is a work prepared by an officer or employee of the United States Government as part of that person’s official duties under the terms of Title 17, Chapter 1, Section 105 of the US Code. See Copyright.

Note: This only applies to original works of the Federal Government and not to the work of any individual U.S. state, territory, commonwealth, county, municipality, or any other subdivision. This template also does not apply to postage stamp designs published by the United States Postal Service since 1978. (See 206.02(b) of Compendium II: Copyright Office Practices). It also does not apply to certain US coins; see The US Mint Terms of Use.
Great Seal of the United States (obverse).svg
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights.
The following pages on Schools Wikipedia link to this image (list may be incomplete):

Metadata

This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. If the file has been modified from its original state, some details may not fully reflect the modified file.
Orientation Normal
Horizontal resolution 72 dpi
Vertical resolution 72 dpi
Software used Adobe Photoshop CS Windows
File change date and time 15:42, 20 November 2006
Colour space Uncalibrated

A background to Schools Wikipedia

Wikipedia for Schools was collected by SOS Children. SOS Children's Villages is an international children's charity, providing a good home and loving family to thousands of children who have lost their parents. We also work with communities to help vulnerable families stay together and raise children in the best possible environment. Sponsoring a child is a great way to help children who need your support.