Related Experiment Video
Updated: Apr 4, 2026
11:42
Iterative Optimization of DNA Duplexes for Crystallization of SeqA-DNA Complexes
Published on: November 1, 2012
10.4K
Crystal Structure of Staphylococcus aureus Cas9
Hiroshi Nishimasu1, Le Cong2, Winston X Yan3
1Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; JST, PRESTO, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Cell
|August 29, 2015
Summary
Researchers elucidated the crystal structures of Staphylococcus aureus Cas9 (SaCas9), revealing its mechanism for recognizing diverse DNA targets. This structural insight enables the development of advanced CRISPR-Cas9 genome editing tools.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- CRISPR-Cas9 technology relies on RNA-guided DNA endonucleases like Cas9 for genome editing.
- Staphylococcus aureus Cas9 (SaCas9) is a smaller, more manageable alternative to Streptococcus pyogenes Cas9 (SpCas9) for in vivo applications.
Purpose of the Study:
- To determine the high-resolution crystal structures of SaCas9 bound to guide RNA and target DNA.
- To elucidate the structural basis for SaCas9's relaxed protospacer adjacent motif (PAM) recognition.
- To compare SaCas9 and SpCas9 structures to understand differences in PAM specificity and guide RNA binding.
Main Methods:
- X-ray crystallography was used to obtain structures of SaCas9-sgRNA-DNA complexes.
- Structural analysis and comparison between SaCas9 and SpCas9 were performed.
Main Results:
- Crystal structures of SaCas9 with two distinct DNA targets (5'-TTGAAT-3' PAM and 5'-TTGGGT-3' PAM) were determined at 2.6 and 2.7 Å resolution.
- The structures revealed a mechanism for SaCas9's relaxed recognition of the 5'-NNGRRT-3' PAM sequence.
- Structural comparisons highlighted conserved and divergent features between SaCas9 and SpCas9, explaining their differing PAM specificities.
Conclusions:
- The structural insights into SaCas9 provide a foundation for understanding its unique PAM recognition.
- This knowledge facilitates the rational design of novel CRISPR-Cas9 based genome editing tools, including transcriptional activators and inducible nucleases.
Related Concept Videos
01:59CRISPR
59.3K
Genome editing technologies allow scientists to modify an organism’s DNA via the addition, removal, or rearrangement of genetic material at specific genomic locations. These types of techniques could potentially be used to cure genetic disorders such as hemophilia and sickle cell anemia. One popular and widely used DNA-editing research tool that could lead to safe and effective cures for genetic disorders is the CRISPR-Cas9 system. CRISPR-Cas9 stands for Clustered Regularly Interspaced...
59.3K
02:53CRISPR and crRNAs
19.6K
Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect themselves. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) are present in more than 45% of known bacteria and 90% of known archaea.
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
19.6K
01:28CRISPR/Cas9 Genome Editing
2.7K
The CRISPR-Cas system serves as a bacterial defense mechanism against invading genetic elements such as viruses and plasmids, forming the foundation for its adaptation as a powerful genome-editing tool. Originally discovered in prokaryotes, this system has been repurposed to revolutionize genetic engineering across a wide range of organisms, including plants, animals, and humans. The core component, Cas9, is an endonuclease derived from Streptococcus pyogenes, capable of introducing...
2.7K
01:23The Antiviral System of Bacteria and Archaea: CRISPR
999
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats is a adaptive immune system found in bacteria and archaea that protects against viral infections. This system enables prokaryotic cells to identify, remember, and neutralize foreign genetic elements, primarily bacteriophages, by storing fragments of the invader’s DNA as a genetic memory.The CRISPR immune response begins during an initial infection. Cas (CRISPR-associated) proteins play a central role in this...
999
01:29Staphylococcal Skin Infections
72
Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
72
01:18ATP Synthase: Structure
17.7K
ATP synthase or ATPase is among the most conserved proteins found in bacteria, mammals, and plants. This enzyme can catalyze a forward reaction in response to the electrochemical gradient, producing ATP from ADP and inorganic phosphate. ATP synthase can also work in a reverse direction by hydrolyzing ATP and generating an electrochemical gradient. Different forms of ATP synthases have evolved special features to meet the specific demands of the cell. Based on their specific feature, ATP...
17.7K