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Newsom SN, Wang DS, Rostami S, Schuster I, Parameshwaran HP, Joseph YG, Qin PZ, Liu J, Rajan R. Differential Divalent Metal Binding by SpyCas9's RuvC Active Site Contributes to Nonspecific DNA Cleavage. CRISPR J 2023; 6:527-542. [PMID: 38108519 PMCID: PMC10753984 DOI: 10.1089/crispr.2023.0022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 11/10/2023] [Indexed: 12/19/2023] Open
Abstract
To protect against mobile genetic elements (MGEs), some bacteria and archaea have clustered regularly interspaced short palindromic repeats-CRISPR associated (CRISPR-Cas) adaptive immune systems. CRISPR RNAs (crRNAs) bound to Cas nucleases hybridize to MGEs based on sequence complementarity to guide the nucleases to cleave the MGEs. This programmable DNA cleavage has been harnessed for gene editing. Safety concerns include off-target and guide RNA (gRNA)-free DNA cleavages, both of which are observed in the Cas nuclease commonly used for gene editing, Streptococcus pyogenes Cas9 (SpyCas9). We developed a SpyCas9 variant (SpyCas9H982A) devoid of gRNA-free DNA cleavage activity that is more selective for on-target cleavage. The H982A substitution in the metal-dependent RuvC active site reduces Mn2+-dependent gRNA-free DNA cleavage by ∼167-fold. Mechanistic molecular dynamics analysis shows that Mn2+, but not Mg2+, produces a gRNA-free DNA cleavage competent state that is disrupted by the H982A substitution. Our study demonstrates the feasibility of modulating cation:protein interactions to engineer safer gene editing tools.
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Affiliation(s)
- Sydney N. Newsom
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, Oklahoma, USA
| | - Duen-Shian Wang
- Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Saadi Rostami
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, Oklahoma, USA
| | - Isabelle Schuster
- Department of Chemistry, University of Southern California, Los Angeles, California, USA
| | - Hari Priya Parameshwaran
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, Oklahoma, USA
| | - Yadin G. Joseph
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, Oklahoma, USA
| | - Peter Z. Qin
- Department of Chemistry, University of Southern California, Los Angeles, California, USA
| | - Jin Liu
- Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, Oklahoma, USA
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Babu K, Kathiresan V, Kumari P, Newsom S, Parameshwaran HP, Chen X, Liu J, Qin PZ, Rajan R. Coordinated Actions of Cas9 HNH and RuvC Nuclease Domains Are Regulated by the Bridge Helix and the Target DNA Sequence. Biochemistry 2021; 60:3783-3800. [PMID: 34757726 PMCID: PMC8675354 DOI: 10.1021/acs.biochem.1c00354] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/23/2021] [Indexed: 12/22/2022]
Abstract
CRISPR-Cas systems are RNA-guided nucleases that provide adaptive immune protection in bacteria and archaea against intruding genomic materials. Cas9, a type-II CRISPR effector protein, is widely used for gene editing applications since a single guide RNA can direct Cas9 to cleave specific genomic targets. The conformational changes associated with RNA/DNA binding are being modulated to develop Cas9 variants with reduced off-target cleavage. Previously, we showed that proline substitutions in the arginine-rich bridge helix (BH) of Streptococcus pyogenes Cas9 (SpyCas9-L64P-K65P, SpyCas92Pro) improve target DNA cleavage selectivity. In this study, we establish that kinetic analysis of the cleavage of supercoiled plasmid substrates provides a facile means to analyze the use of two parallel routes for DNA linearization by SpyCas9: (i) nicking by HNH followed by RuvC cleavage (the TS (target strand) pathway) and (ii) nicking by RuvC followed by HNH cleavage (the NTS (nontarget strand) pathway). BH substitutions and DNA mismatches alter the individual rate constants, resulting in changes in the relative use of the two pathways and the production of nicked and linear species within a given pathway. The results reveal coordinated actions between HNH and RuvC to linearize DNA, which is modulated by the integrity of the BH and the position of the mismatch in the substrate, with each condition producing distinct conformational energy landscapes as observed by molecular dynamics simulations. Overall, our results indicate that BH interactions with RNA/DNA enable target DNA discrimination through the differential use of the parallel sequential pathways driven by HNH/RuvC coordination.
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Affiliation(s)
- Kesavan Babu
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Venkatesan Kathiresan
- Department
of Chemistry, University of Southern California, 3430 S. Vermont Ave., Los Angeles, California 90089, United States
| | - Pratibha Kumari
- Department
of Pharmaceutical Sciences, University of North Texas System College
of Pharmacy, University of North Texas Health
Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107, United
States
| | - Sydney Newsom
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Hari Priya Parameshwaran
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Xiongping Chen
- Department
of Pharmaceutical Sciences, University of North Texas System College
of Pharmacy, University of North Texas Health
Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107, United
States
| | - Jin Liu
- Department
of Pharmaceutical Sciences, University of North Texas System College
of Pharmacy, University of North Texas Health
Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas 76107, United
States
| | - Peter Z. Qin
- Department
of Chemistry, University of Southern California, 3430 S. Vermont Ave., Los Angeles, California 90089, United States
| | - Rakhi Rajan
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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Parameshwaran HP, Babu K, Martin L, Tran C, Allen A, Qin P, Rajan R. Role Of Bridge Helix In Mediating DNA Recognition And Efficient Cleavage By CRISPR‐ Cas12a. FASEB J 2021. [DOI: 10.1096/fasebj.2021.35.s1.04306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Kesavan Babu
- Chemistry and BiochemistryUniversity of OklahomaNormanOK
| | - Lindsie Martin
- Chemistry and BiochemistryUniversity of OklahomaNormanOK
| | - Christine Tran
- Chemistry and BiochemistryUniversity of OklahomaNormanOK
| | - Aleiqué Allen
- ChemistryUniversity of Southern CaliforniaLos AngelesCA
| | - Peter Qin
- ChemistryUniversity of Southern CaliforniaLos AngelesCA
| | - Rakhi Rajan
- Chemistry and BiochemistryUniversity of OklahomaNormanOK
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Parameshwaran HP, Babu K, Tran C, Guan K, Allen A, Kathiresan V, Qin PZ, Rajan R. The bridge helix of Cas12a imparts selectivity in cis-DNA cleavage and regulates trans-DNA cleavage. FEBS Lett 2021; 595:892-912. [PMID: 33523494 PMCID: PMC8044059 DOI: 10.1002/1873-3468.14051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 01/15/2021] [Accepted: 01/21/2021] [Indexed: 12/26/2022]
Abstract
Cas12a is an RNA-guided DNA endonuclease of the type V-A CRISPR-Cas system that has evolved convergently with the type II Cas9 protein. We previously showed that proline substitutions in the bridge helix (BH) impart target DNA cleavage selectivity in Streptococcus pyogenes (Spy) Cas9. Here, we examined a BH variant of Cas12a from Francisella novicida (FnoCas12aKD2P ) to test mechanistic conservation. Our results show that for RNA-guided DNA cleavage (cis-activity), FnoCas12aKD2P accumulates nicked products while cleaving supercoiled DNA substrates with mismatches, with certain mismatch positions being more detrimental for linearization. FnoCas12aKD2P also possess reduced trans-single-stranded DNA cleavage activity. These results implicate the BH in substrate selectivity in both cis- and trans-cleavages and show its conserved role in target discrimination among Cas nucleases.
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Affiliation(s)
- Hari Priya Parameshwaran
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, University of Oklahoma, Stephenson Life Sciences Research Center, Norman, OK, USA
| | - Kesavan Babu
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, University of Oklahoma, Stephenson Life Sciences Research Center, Norman, OK, USA
| | - Christine Tran
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, University of Oklahoma, Stephenson Life Sciences Research Center, Norman, OK, USA
| | - Kevin Guan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, University of Oklahoma, Stephenson Life Sciences Research Center, Norman, OK, USA
| | - Aleique Allen
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | | | - Peter Z Qin
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, University of Oklahoma, Stephenson Life Sciences Research Center, Norman, OK, USA
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Newsom S, Parameshwaran HP, Martin L, Rajan R. The CRISPR-Cas Mechanism for Adaptive Immunity and Alternate Bacterial Functions Fuels Diverse Biotechnologies. Front Cell Infect Microbiol 2021; 10:619763. [PMID: 33585286 PMCID: PMC7876343 DOI: 10.3389/fcimb.2020.619763] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 12/14/2020] [Indexed: 12/26/2022] Open
Abstract
Bacterial and archaeal CRISPR-Cas systems offer adaptive immune protection against foreign mobile genetic elements (MGEs). This function is regulated by sequence specific binding of CRISPR RNA (crRNA) to target DNA/RNA, with an additional requirement of a flanking DNA motif called the protospacer adjacent motif (PAM) in certain CRISPR systems. In this review, we discuss how the same fundamental mechanism of RNA-DNA and/or RNA-RNA complementarity is utilized by bacteria to regulate two distinct functions: to ward off intruding genetic materials and to modulate diverse physiological functions. The best documented examples of alternate functions are bacterial virulence, biofilm formation, adherence, programmed cell death, and quorum sensing. While extensive complementarity between the crRNA and the targeted DNA and/or RNA seems to constitute an efficient phage protection system, partial complementarity seems to be the key for several of the characterized alternate functions. Cas proteins are also involved in sequence-specific and non-specific RNA cleavage and control of transcriptional regulator expression, the mechanisms of which are still elusive. Over the past decade, the mechanisms of RNA-guided targeting and auxiliary functions of several Cas proteins have been transformed into powerful gene editing and biotechnological tools. We provide a synopsis of CRISPR technologies in this review. Even with the abundant mechanistic insights and biotechnology tools that are currently available, the discovery of new and diverse CRISPR types holds promise for future technological innovations, which will pave the way for precision genome medicine.
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Affiliation(s)
- Sydney Newsom
- Department of Chemistry and Biochemistry, Price Family Foundation Structural Biology Center, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, United States
| | - Hari Priya Parameshwaran
- Department of Chemistry and Biochemistry, Price Family Foundation Structural Biology Center, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, United States
| | - Lindsie Martin
- Department of Chemistry and Biochemistry, Price Family Foundation Structural Biology Center, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, United States
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Structural Biology Center, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, United States
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Jiang W, Singh J, Allen A, Li Y, Kathiresan V, Qureshi O, Tangprasertchai N, Zhang X, Parameshwaran HP, Rajan R, Qin PZ. CRISPR-Cas12a Nucleases Bind Flexible DNA Duplexes without RNA/DNA Complementarity. ACS Omega 2019; 4:17140-17147. [PMID: 31656887 PMCID: PMC6811856 DOI: 10.1021/acsomega.9b01469] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/25/2019] [Indexed: 05/03/2023]
Abstract
Cas12a (also known as "Cpf1") is a class 2 type V-A CRISPR-associated nuclease that can cleave double-stranded DNA at specific sites. The Cas12a effector enzyme comprises a single protein and a CRISPR-encoded small RNA (crRNA) and has been used for genome editing and manipulation. Work reported here examined in vitro interactions between the Cas12a effector enzyme and DNA duplexes with varying states of base-pairing between the two strands. The data revealed that in the absence of complementarity between the crRNA guide and the DNA target-strand, Cas12a binds duplexes with unpaired segments. These off-target duplexes were bound at the Cas12a site responsible for RNA-guided double-stranded DNA binding but were not cleaved due to the lack of RNA/DNA hybrid formation. Such promiscuous binding was attributed to increased DNA flexibility induced by the unpaired segment present next to the protospacer-adjacent-motif. The results suggest that target discrimination of Cas12a can be influenced by flexibility of the DNA. As such, in addition to the linear sequence, flexibility and other physical properties of the DNA should be considered in Cas12a-based genome engineering applications.
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Affiliation(s)
- Wei Jiang
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Jaideep Singh
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Aleique Allen
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Yue Li
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Venkatesan Kathiresan
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Omair Qureshi
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Narin Tangprasertchai
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Xiaojun Zhang
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
| | - Hari Priya Parameshwaran
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Rakhi Rajan
- Department
of Chemistry and Biochemistry, Price Family Foundation Institute of
Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Peter Z. Qin
- Department of Chemistry andDepartment of
Biological Sciences, University of Southern
California, Los Angeles, California 90089, United States
- E-mail: . Phone: (213) 821-2461. Fax: (213) 740-2701
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