Related Experiment Video
Updated: Mar 6, 2026
08:07
Analyzing DNA-Protein Interactions with Streptavidin-Based Biolayer Interferometry
Published on: January 17, 2025
2.3K
Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein
Sarah Willkomm1, Christine A Oellig2, Adrian Zander1
1Institute of Microbiology, University of Regensburg, 93053 Regensburg, Germany.
Nature Microbiology
|March 21, 2017
Summary
Archaeal Argonaute (Ago) proteins protect against invading DNA. Structural studies reveal how guide DNA binding and specific nucleotides in Methanocaldococcus jannaschii Ago influence DNA-silencing activity.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Argonaute (Ago) proteins are crucial for post-transcriptional gene silencing in eukaryotes.
- Prokaryotic Ago proteins are increasingly recognized for their roles in defending against foreign DNA.
- Understanding archaeal Ago function provides insights into diverse biological defense mechanisms.
Purpose of the Study:
- To elucidate the structural basis of DNA-guided DNA silencing by the archaeal Methanocaldococcus jannaschii (Mj) Ago.
- To identify key structural elements and residues essential for MjAgo's enzymatic activity.
- To investigate the mechanism of guide DNA binding and its impact on MjAgo conformation.
Main Methods:
- X-ray crystallography to determine the structures of apo MjAgo and a binary Ago-guide DNA complex.
- Site-directed mutagenesis to generate MjAgo mutants.
- Biochemical assays to assess the cleavage activity of MjAgo and its mutants.
Main Results:
- Crystal structures revealed significant conformational changes in MjAgo upon guide DNA binding, including rearrangements in a switch helix region.
- Mutational analysis indicated that the 3' and 5' terminal nucleotides of the guide DNA, along with the switch helix, are critical for MjAgo's DNA cleavage activity.
- The study identified key residues and structural features governing MjAgo's DNA-guided DNA silencing function.
Conclusions:
- MjAgo undergoes substantial structural rearrangements upon guide DNA binding, essential for its function.
- Specific nucleotide interactions and the switch helix play pivotal roles in modulating MjAgo's DNA silencing activity.
- This work provides fundamental insights into the molecular mechanisms of DNA-guided DNA silencing in archaea.
Related Concept Videos
02:26Conservation of Protein Domains Over Different Proteins
14.8K
Protein domains are small structurally independent units that are part of a single amino acid chain. Although these domains are often structurally independent, they may rely on synergistic effects to perform their functions as part of a larger protein. Protein domains may be conserved within the same organism, as well as across different organisms.
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to...
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to...
14.8K
03:01The Replisome
39.0K
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...
39.0K
01:24Nucleoid
1.4K
The nucleoid represents a structurally and functionally distinct region within prokaryotic cells, where the cell's DNA and associated proteins are housed. Unlike eukaryotic cells, prokaryotes lack a membrane-bound nucleus, and the nucleoid facilitates the organization and accessibility of the genetic material within this constraint. The DNA in most bacteria and archaea exists as a single, circular, double-stranded molecule that is highly compacted through supercoiling and interactions with...
1.4K
00:55DNA Helicases
24.6K
DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
24.6K
01:59Lagging Strand Synthesis
62.2K
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
62.2K
01:27Diversity of Archaea III
406
Crenarchaeota, a prominent phylum of Archaea, is remarkable for its ability to thrive in extreme environments characterized by high temperatures and acidity. These microorganisms inhabit sulfuric hot springs, volcanic systems, and submarine hydrothermal vents, where temperatures often exceed 100°C. The unique adaptations of Crenarchaeota not only allow survival under such extreme conditions but also provide insights into the mechanisms of life in primordial Earth-like...
406