1
|
Correa A, Shehreen S, Machado LC, Thesier J, Cunic L, Petassi M, Chu J, Kapili B, Jia Y, England K, Peters J. Novel mechanisms of diversity generation in Acinetobacter baumannii resistance islands driven by Tn7-like elements. Nucleic Acids Res 2024; 52:3180-3198. [PMID: 38407477 PMCID: PMC11014353 DOI: 10.1093/nar/gkae129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 01/25/2024] [Accepted: 02/09/2024] [Indexed: 02/27/2024] Open
Abstract
Mobile genetic elements play an important role in the acquisition of antibiotic and biocide resistance, especially through the formation of resistance islands in bacterial chromosomes. We analyzed the contribution of Tn7-like transposons to island formation and diversification in the nosocomial pathogen Acinetobacter baumannii and identified four separate families that recognize different integration sites. One integration site is within the comM gene and coincides with the previously described Tn6022 elements suggested to account for the AbaR resistance island. We established Tn6022 in a heterologous E. coli host and confirmed basic features of transposition into the comM attachment site and the use of a novel transposition protein. By analyzing population features within Tn6022 elements we identified two potential novel transposon-encoded diversification mechanisms with this dynamic genetic island. The activities of these diversification features were confirmed in E. coli. One was a novel natural gain-of-activity allele that could function to broaden transposition targeting. The second was a transposon-encoded hybrid dif-like site that parasitizes the host dimer chromosome resolution system to function with its own tyrosine recombinase. This work establishes a highly active Tn7-like transposon that harnesses novel features allowing the spread and diversification of genetic islands in pathogenic bacteria.
Collapse
Affiliation(s)
- Alberto Correa
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | | | | | - Jordan Thesier
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | - Lille M Cunic
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | | | - Joshua Chu
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | | | - Yu Jia
- College of Life Sciences and Engineering Research Center of Bioreactor and Pharmaceutical Development (Ministry of Education), Jilin Agricultural University, Changchun City, Jilin Province, China
| | - Kevin A England
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | - Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| |
Collapse
|
2
|
Chang CW, Truong VA, Pham NN, Hu YC. RNA-guided genome engineering: paradigm shift towards transposons. Trends Biotechnol 2024:S0167-7799(24)00035-0. [PMID: 38443218 DOI: 10.1016/j.tibtech.2024.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 03/07/2024]
Abstract
CRISPR-Cas systems revolutionized the genome engineering field but need to induce double-strand breaks (DSBs) and may be difficult to deliver due to their large protein size. Tn7-like transposons such as CRISPR-associated transposons (CASTs) can be repurposed for RNA-guided DSB-free integration, and obligate mobile element guided activity (OMEGA) proteins of the IS200/IS605 transposon family have been developed as hypercompact RNA-guided genome editing tools. CASTs and OMEGA are exciting, innovative genome engineering tools that can improve the precision and efficiency of editing. This review explores the recent developments and uses of CASTs and OMEGA in genome editing across prokaryotic and eukaryotic cells. The pros and cons of these transposon-based systems are deliberated in comparison to other CRISPR systems.
Collapse
Affiliation(s)
- Chin-Wei Chang
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Vy Anh Truong
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Nam Ngoc Pham
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Yu-Chen Hu
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan; Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 300, Taiwan.
| |
Collapse
|
3
|
Garza Elizondo AM, Chappell J. Targeted Transcriptional Activation Using a CRISPR-Associated Transposon System. ACS Synth Biol 2024; 13:328-336. [PMID: 38085703 DOI: 10.1021/acssynbio.3c00563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Synthetic perturbation of gene expression is central to our ability to reliably uncover genotype-phenotype relationships in microbes. Here, we present a novel transcription activation strategy that uses the Vibrio cholerae CRISPR-Associated Transposon (CAST) system to selectively insert promoter elements upstream of genes of interest. Through this strategy, we show robust activation of both recombinant and endogenous genes across the Escherichia coli chromosome. We then demonstrate the precise tuning of expression levels by exchanging the promoter elements being inserted. Finally, we demonstrate that CAST activation can be used to synthetically induce ampicillin-resistant phenotypes in E. coli.
Collapse
Affiliation(s)
| | - James Chappell
- Department of Biosciences, Rice University, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| |
Collapse
|
4
|
Koonin EV, Krupovic M. New faces of prokaryotic mobile genetic elements: guide RNAs link transposition with host defense mechanisms. CURRENT OPINION IN SYSTEMS BIOLOGY 2023; 36:100473. [PMID: 37779558 PMCID: PMC10538440 DOI: 10.1016/j.coisb.2023.100473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Most life forms harbor multiple, diverse mobile genetic elements (MGE) that widely differ in their rates and mechanisms of mobility. Recent findings on two classes of MGE in prokaryotes revealed a novel mechanism, RNA-guided transposition, where a transposon-encoded guide RNA directs the transposase to a unique site in the host genome. Tn7-like transposons, on multiple occasions, recruited CRISPR systems that lost the capacity to cleave target DNA and instead mediate RNA-guided transposition via CRISPR RNA. Conversely, the abundant transposon-associated, RNA-guided nucleases IscB and TnpB that appear to promote proliferation of IS200/IS605 and IS607 transposons were the likely evolutionary ancestors of type II and type V CRISPR systems, respectively. Thus, RNA-guided target recognition is a major biological phenomenon that connects MGE with host defense mechanisms. More RNA-guided defensive and MGE-associated functionalities are likely to be discovered.
Collapse
Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, 25 rue du Dr Roux, 75015 Paris
| |
Collapse
|
5
|
George JT, Acree C, Park JU, Kong M, Wiegand T, Pignot YL, Kellogg EH, Greene EC, Sternberg SH. Mechanism of target site selection by type V-K CRISPR-associated transposases. Science 2023; 382:eadj8543. [PMID: 37972161 PMCID: PMC10771339 DOI: 10.1126/science.adj8543] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/23/2023] [Indexed: 11/19/2023]
Abstract
CRISPR-associated transposases (CASTs) repurpose nuclease-deficient CRISPR effectors to catalyze RNA-guided transposition of large genetic payloads. Type V-K CASTs offer potential technology advantages but lack accuracy, and the molecular basis for this drawback has remained elusive. Here, we reveal that type V-K CASTs maintain an RNA-independent, "untargeted" transposition pathway alongside RNA-dependent integration, driven by the local availability of TnsC filaments. Using cryo-electron microscopy, single-molecule experiments, and high-throughput sequencing, we found that a minimal, CRISPR-less transpososome preferentially directs untargeted integration at AT-rich sites, with additional local specificity imparted by TnsB. By exploiting this knowledge, we suppressed untargeted transposition and increased type V-K CAST specificity up to 98.1% in cells without compromising on-target integration efficiency. These findings will inform further engineering of CAST systems for accurate, kilobase-scale genome engineering applications.
Collapse
Affiliation(s)
- Jerrin Thomas George
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Christopher Acree
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Jung-Un Park
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Muwen Kong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Tanner Wiegand
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Yanis Luca Pignot
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Elizabeth H. Kellogg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Samuel H. Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| |
Collapse
|
6
|
George JT, Acree C, Park JU, Kong M, Wiegand T, Pignot YL, Kellogg EH, Greene EC, Sternberg SH. Mechanism of target site selection by type V-K CRISPR-associated transposases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.14.548620. [PMID: 37503092 PMCID: PMC10370016 DOI: 10.1101/2023.07.14.548620] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Unlike canonical CRISPR-Cas systems that rely on RNA-guided nucleases for target cleavage, CRISPR-associated transposases (CASTs) repurpose nuclease-deficient CRISPR effectors to facilitate RNA-guided transposition of large genetic payloads. Type V-K CASTs offer several potential upsides for genome engineering, due to their compact size, easy programmability, and unidirectional integration. However, these systems are substantially less accurate than type I-F CASTs, and the molecular basis for this difference has remained elusive. Here we reveal that type V-K CASTs undergo two distinct mobilization pathways with remarkably different specificities: RNA-dependent and RNA-independent transposition. Whereas RNA-dependent transposition relies on Cas12k for accurate target selection, RNA-independent integration events are untargeted and primarily driven by the local availability of TnsC filaments. The cryo-EM structure of the untargeted complex reveals a TnsB-TnsC-TniQ transpososome that encompasses two turns of a TnsC filament and otherwise resembles major architectural aspects of the Cas12k-containing transpososome. Using single-molecule experiments and genome-wide meta-analyses, we found that AT-rich sites are preferred substrates for untargeted transposition and that the TnsB transposase also imparts local specificity, which collectively determine the precise insertion site. Knowledge of these motifs allowed us to direct untargeted transposition events to specific hotspot regions of a plasmid. Finally, by exploiting TnsB's preference for on-target integration and modulating the availability of TnsC, we suppressed RNA-independent transposition events and increased type V-K CAST specificity up to 98.1%, without compromising the efficiency of on-target integration. Collectively, our results reveal the importance of dissecting target site selection mechanisms and highlight new opportunities to leverage CAST systems for accurate, kilobase-scale genome engineering applications.
Collapse
Affiliation(s)
- Jerrin Thomas George
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Christopher Acree
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Present address: Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37212, USA
| | - Jung-Un Park
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
- Future address: Department of Structural Biology. St Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Muwen Kong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Tanner Wiegand
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Yanis Luca Pignot
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Present address: Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Elizabeth H. Kellogg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
- Future address: Department of Structural Biology. St Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Samuel H. Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| |
Collapse
|