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

December 9, 2008
Mcm10 is shown in a surface view interacting with a single strand of DNA (depicted in red). Mcm10 contains two classic binding scaffolds. One is an OB-fold (OB stands for oligonucleotide/oligosaccharide) shown in green. The other is a structure called a zinc finger shown in blue. Proteins typically use OB-folds to interact with single-stranded DNA, while zinc fingers are used normally to recognize double-stranded DNA segments. Image: Brandt Eichman, Vanderbilt University

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.

Source: Vanderbilt University

Explore further: Origins of life: New model may explain emergence of self-replication on early Earth

Related Stories

How to make chromosomes from DNA

July 28, 2015

Researchers at the University of Tokyo have discovered a long-overlooked process important for converting a long, string-like DNA molecule into a chromosome. This finding gives us a better understanding of the mechanism of ...

Understanding the molecular origin of epigenetic markers

July 28, 2015

Researchers at the Institute for Research in Biomedicine (IRB Barcelona), Cambridge University and New York University, led by Modesto Orozco, Group Leader at IRB Barcelona, Director of Life Sciences at the Barcelona Supercomputing ...

The mystery of the instant noodle chromosomes

July 23, 2015

A group of researchers from the Lomonosov Moscow State University tried to address one of the least understood issues in the modern molecular biology, namely, how do strands of DNA pack themselves into the cell nucleus. Scientists ...

Team shows a protein modification determines enzyme's fate

July 15, 2015

The human genome encodes roughly 20,000 genes, only a few thousand more than fruit flies. The complexity of the human body, therefore, comes from far more than just the sequence of nucleotides that comprise our DNA, it arises ...

Recommended for you

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

Studies reveal details of error correction in cell division

July 29, 2015

Cell biologists led by Thomas Maresca at the University of Massachusetts Amherst, with collaborators elsewhere, report an advance in understanding the workings of an error correction mechanism that helps cells detect and ...

Dense star clusters shown to be binary black hole factories

July 29, 2015

The coalescence of two black holes—a very violent and exotic event—is one of the most sought-after observations of modern astronomy. But, as these mergers emit no light of any kind, finding such elusive events has been ...

Yarn from slaughterhouse waste

July 29, 2015

ETH researchers have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibers. Now they are working on making the yarn even more water resistant.

Scientists unlock secrets of stars through aluminium

July 29, 2015

Physicists at the University of York have revealed a new understanding of nucleosynthesis in stars, providing insight into the role massive stars play in the evolution of the Milky Way and the origins of the Solar System.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.