First 3-D images obtained of core component of molecular machinery used for cell reproduction

December 09, 2008

For the first time, structural biologists have managed to obtain the detailed three-dimensional structure of one of the proteins that form the core of the complex molecular machine, called the replisome, that plant and animal cells assemble to copy their DNA as the first step in cell reproduction.

The molecular structure of the protein, Mcm10, was published online by the journal Structure on Dec. 9. Its discovery was a collaborative effort by Brandt Eichman, assistant professor of biological sciences at Vanderbilt University, and Walter Chazin, Chancellor's Professor of Biochemistry and Physics at Vanderbilt, working with Anja Katrin-Bielinsky at the University of Minnesota.

Currently, the process of DNA replication in eukaryote cells - cells that have their genetic information contained in a nucleus - is a "black box." Biologists know what goes in and what comes out but they know very little about how the process actual works at the molecular level. Because form causes function in the protein world, determining the 3D structure of the 30-40 proteins that combine to form the replisome is a necessary first step to figuring out the details of this critical process and understanding how it can go wrong.

The structure of Mcm10 was determined using cells from the African clawed frog (Xenopus laevis); the structures of analogous proteins in human and other animal cells should be nearly identical, the researchers maintain. The Mcm10 structure reveals a special feature, called the OB-fold, that proteins use to interact with single-stranded DNA and a series of three loops that the researchers believe are used to clamp down on the DNA. The protein also contains a protrusion - called a zinc finger because it is built around a zinc atom - that proteins normally use to recognize specific double-stranded DNA segments. In this case the zinc finger appears to be modified in a way that allows it to detect generic DNA.

The researchers think that Mcm10 may play a role in positioning the other proteins in the replisome onto the single DNA strand so that it may be correctly read and duplicated, while acknowledging that they have very little information about how it functions.
-end-
The research was funded in part by a grant from the National institutes of Health.

For more news about Vanderbilt, visit the Vanderbilt News Service homepage on the Internet at www.vanderbilt.edu/News.

Vanderbilt University

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.