What is the structure of DNA polymerase III?

In summary, there is some disagreement about the exact structure of DNA polymerase III and its clamp loader, with one source presenting a more minimal and direct representation while another involves more speculation and imagination. It is difficult to directly image large multiprotein complexes like DNA pol III, and information about their architecture often comes from cryo-electron microscopy studies. The Lehninger diagram is commonly seen, but it may be worth contacting the authors for additional references.
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Tyto alba
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According to Snustard and Simmons the structure of DNA polymerase III is the following, where the clamp loader( γ -δ complex ) is present on one side:

LNAQ4.png


But according to Lehninger the clamp loader is centrally located:

CIEeJ.png


Which one is right? Besides where can I find a correct diagrammatic representation of DNA polymerase III?
 
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I'm not sure if either diagram can be called "right." Most of these diagrams are based on only limited information (e.g. which parts are directly touching each other), but very often, it is difficult to directly image large multiprotein complexes such as DNA pol III. Information about the architecture of large complexes often comes from cryo-electron microscopy studies. A quick google search shows cryo-EM studies of parts of the complex (e.g. https://elifesciences.org/content/4/e11134) but I didn't find any of the entire complex.

The Snustard and Simmons is probably right in that it present a minimal set of information about the complex without adding in unknown details (here the relative arrangement of the subunits is not meaningful, only the relative sizes and which subunits are directly contacting). The Lehninger diagram, however, involves a bit more imagination in thinking about how all of the pieces might fit together. This is definitely the one I've most often seen, though I'm not sure the extent to which it is based on actual evidence. Perhaps you could email the authors to see if they can provide any helpful references.
 
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Thank you for your advice, I really appreciate it.
 

FAQ: What is the structure of DNA polymerase III?

1. What is the function of DNA polymerase III?

DNA polymerase III is an enzyme responsible for synthesizing new DNA strands during DNA replication. It adds nucleotides onto the growing DNA strand, using the existing strand as a template.

2. What is the structure of DNA polymerase III?

DNA polymerase III is a complex protein made up of multiple subunits. It has a large catalytic subunit responsible for adding nucleotides to the growing DNA strand, as well as smaller subunits that help with the process and regulate its activity.

3. How does DNA polymerase III differ from DNA polymerase I and II?

DNA polymerase III is the main enzyme involved in DNA replication, while DNA polymerase I and II have other functions, such as repairing damaged DNA. Additionally, DNA polymerase III has a much higher processivity (ability to add many nucleotides in a row) compared to the other two polymerases.

4. What is the role of the proofreading activity of DNA polymerase III?

DNA polymerase III has a built-in proofreading activity that helps ensure the accuracy of DNA replication. It can detect and correct errors in the newly synthesized DNA strand, increasing the overall fidelity of DNA replication.

5. How is the activity of DNA polymerase III regulated?

The activity of DNA polymerase III is regulated by various factors, including the concentration of nucleotides and the presence of other proteins that assist in DNA replication. It also has its own built-in proofreading activity that helps maintain the accuracy of DNA replication.

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