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Ganguly C, Rostami S, Long K, Aribam SD, Rajan R. Unity among the diverse RNA-guided CRISPR-Cas interference mechanisms. J Biol Chem 2024; 300:107295. [PMID: 38641067 PMCID: PMC11127173 DOI: 10.1016/j.jbc.2024.107295] [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] [Received: 06/24/2023] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/21/2024] Open
Abstract
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems are adaptive immune systems that protect bacteria and archaea from invading mobile genetic elements (MGEs). The Cas protein-CRISPR RNA (crRNA) complex uses complementarity of the crRNA "guide" region to specifically recognize the invader genome. CRISPR effectors that perform targeted destruction of the foreign genome have emerged independently as multi-subunit protein complexes (Class 1 systems) and as single multi-domain proteins (Class 2). These different CRISPR-Cas systems can cleave RNA, DNA, and protein in an RNA-guided manner to eliminate the invader, and in some cases, they initiate programmed cell death/dormancy. The versatile mechanisms of the different CRISPR-Cas systems to target and destroy nucleic acids have been adapted to develop various programmable-RNA-guided tools and have revolutionized the development of fast, accurate, and accessible genomic applications. In this review, we present the structure and interference mechanisms of different CRISPR-Cas systems and an analysis of their unified features. The three types of Class 1 systems (I, III, and IV) have a conserved right-handed helical filamentous structure that provides a backbone for sequence-specific targeting while using unique proteins with distinct mechanisms to destroy the invader. Similarly, all three Class 2 types (II, V, and VI) have a bilobed architecture that binds the RNA-DNA/RNA hybrid and uses different nuclease domains to cleave invading MGEs. Additionally, we highlight the mechanistic similarities of CRISPR-Cas enzymes with other RNA-cleaving enzymes and briefly present the evolutionary routes of the different CRISPR-Cas systems.
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Affiliation(s)
- Chhandosee Ganguly
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Saadi Rostami
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Kole Long
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Swarmistha Devi Aribam
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA.
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Abstract
The study of eukaryotic tRNA processing has given rise to an explosion of new information and insights in the last several years. We now have unprecedented knowledge of each step in the tRNA processing pathway, revealing unexpected twists in biochemical pathways, multiple new connections with regulatory pathways, and numerous biological effects of defects in processing steps that have profound consequences throughout eukaryotes, leading to growth phenotypes in the yeast Saccharomyces cerevisiae and to neurological and other disorders in humans. This review highlights seminal new results within the pathways that comprise the life of a tRNA, from its birth after transcription until its death by decay. We focus on new findings and revelations in each step of the pathway including the end-processing and splicing steps, many of the numerous modifications throughout the main body and anticodon loop of tRNA that are so crucial for tRNA function, the intricate tRNA trafficking pathways, and the quality control decay pathways, as well as the biogenesis and biology of tRNA-derived fragments. We also describe the many interactions of these pathways with signaling and other pathways in the cell.
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Affiliation(s)
- Eric M Phizicky
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Anita K Hopper
- Department of Molecular Genetics and Center for RNA Biology, Ohio State University, Columbus, Ohio 43235, USA
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Tocchini-Valentini GD, Tocchini-Valentini GP. Archaeal tRNA-Splicing Endonuclease as an Effector for RNA Recombination and Novel Trans-Splicing Pathways in Eukaryotes. J Fungi (Basel) 2021; 7:jof7121069. [PMID: 34947051 PMCID: PMC8707768 DOI: 10.3390/jof7121069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/09/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
We have characterized a homodimeric tRNA endonuclease from the euryarchaeota Ferroplasma acidarmanus (FERAC), a facultative anaerobe which can grow at temperatures ranging from 35 to 42 °C. This enzyme, contrary to the eukaryal tRNA endonucleases and the homotetrameric Methanocaldococcus jannaschii (METJA) homologs, is able to cleave minimal BHB (bulge–helix–bulge) substrates at 30 °C. The expression of this enzyme in Schizosaccharomyces pombe (SCHPO) enables the use of its properties as effectors by inserting BHB motif introns into hairpin loops normally seen in mRNA transcripts. In addition, the FERAC endonuclease can create proteins with new functionalities through the recombination of protein domains.
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Affiliation(s)
- Giuseppe D. Tocchini-Valentini
- Istituto di Biochimica e Biologia Cellulare, Campus Internazionale “A. Buzzati-Traverso”, Dipartimento Scienze Biomediche, Consiglio Nazionale delle Ricerche, via Ramarini 32, 00015 Monterotondo, Rome, Italy;
- Dipartimento Scienze Biomediche, European Mouse Mutant Archive (EMMA), INFRAFRONTIER-IMPC, Monterotondo Mouse Clinic, Campus Internazionale “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, via Ramarini 32, 00015 Monterotondo, Rome, Italy
- Correspondence:
| | - Glauco P. Tocchini-Valentini
- Istituto di Biochimica e Biologia Cellulare, Campus Internazionale “A. Buzzati-Traverso”, Dipartimento Scienze Biomediche, Consiglio Nazionale delle Ricerche, via Ramarini 32, 00015 Monterotondo, Rome, Italy;
- Dipartimento Scienze Biomediche, European Mouse Mutant Archive (EMMA), INFRAFRONTIER-IMPC, Monterotondo Mouse Clinic, Campus Internazionale “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, via Ramarini 32, 00015 Monterotondo, Rome, Italy
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Francis BR. Evolution of the genetic code by incorporation of amino acids that improved or changed protein function. J Mol Evol 2013; 77:134-58. [PMID: 23743924 DOI: 10.1007/s00239-013-9567-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/25/2013] [Indexed: 12/31/2022]
Abstract
Fifty years have passed since the genetic code was deciphered, but how the genetic code came into being has not been satisfactorily addressed. It is now widely accepted that the earliest genetic code did not encode all 20 amino acids found in the universal genetic code as some amino acids have complex biosynthetic pathways and likely were not available from the environment. Therefore, the genetic code evolved as pathways for synthesis of new amino acids became available. One hypothesis proposes that early in the evolution of the genetic code four amino acids-valine, alanine, aspartic acid, and glycine-were coded by GNC codons (N = any base) with the remaining codons being nonsense codons. The other sixteen amino acids were subsequently added to the genetic code by changing nonsense codons into sense codons for these amino acids. Improvement in protein function is presumed to be the driving force behind the evolution of the code, but how improved function was achieved by adding amino acids has not been examined. Based on an analysis of amino acid function in proteins, an evolutionary mechanism for expansion of the genetic code is described in which individual coded amino acids were replaced by new amino acids that used nonsense codons differing by one base change from the sense codons previously used. The improved or altered protein function afforded by the changes in amino acid function provided the selective advantage underlying the expansion of the genetic code. Analysis of amino acid properties and functions explains why amino acids are found in their respective positions in the genetic code.
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Affiliation(s)
- Brian R Francis
- Department of Molecular Biology, University of Wyoming, Laramie, WY, 82071-3944, USA,
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Putti S, Calandra P, Rossi N, Scarabino D, Deidda G, Tocchini-Valentini GP. Highly efficient, in vivo optimized, archaeal endonuclease for controlled RNA splicing in mammalian cells. FASEB J 2013; 27:3466-77. [PMID: 23682120 DOI: 10.1096/fj.13-231993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
ARCHAEA-ExPRESs is an mRNA modification technology that makes use of components derived from the Archaeon Methanocaldococcus jannaschii, namely the tRNA splicing endonuclease (MJ-EndA) and its natural substrate, the bulge-helix-bulge (BHB) structure (1). These components can perform both cis- and trans-splicing in cellular and animal models and may provide a convenient way to modulate gene expression using components independent of cellular regulatory networks. To use MJ-EndA in stable expression mammalian systems, we developed variants characterized by high efficiency and sustainable in vivo activity. The MJ-EndA variants were created by the introduction of proper localization signals followed by mutagenesis and direct selection in mammalian cells. Of note, enzyme selection used an in vivo selection method based on puromycin resistance conferred to cells by BHB-mediated intron splicing from an out-of-frame puromycin N-acetyl transferase (PAC) gene. This approach yielded several endonuclease variants, the best of which showed 40-fold higher activity compared to the parental enzyme and stable processing of 30% of the target mRNA. Notably, these variants showed complete compatibility with long-term expression in mammalian cells, suggesting that they may be usefully applied in functional genomics and genetically modified animal models.
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Affiliation(s)
- Sabrina Putti
- Consiglio Nazionale delle Ricerche, Istituto di Biologia Cellulare e Neurobiologia, European Mouse Mutant Archive, Monterotondo, Italy
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Skipsey M, Hack G, Hooper TA, Shankey MC, Conway LP, Schröder M, Hodgson DRW. 5'-deoxy-5'-hydrazinylguanosine as an initiator of T7 Rna polymerase-catalyzed transcriptions for the preparation of labeling-ready RNAs. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2013; 32:670-81. [PMID: 24328564 PMCID: PMC3924349 DOI: 10.1080/15257770.2013.851393] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/29/2013] [Indexed: 12/03/2022]
Abstract
5'-deoxy-5'-hydrazinylguanosine was incorporated into the 5'-termini of RNA transcripts using T7 RNA polymerase. Transcriptions provided 5'-hydrazinyl-RNA that was readily labeled and purified. The use of fluorophore-labeled material was validated in an endoribonuclease activity assay.
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Affiliation(s)
- Mark Skipsey
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Gordon Hack
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
- School of Biological and Biomedical Sciences and Biophysical Sciences Institute. Durham University, Durham, United Kingdom
| | - Thomas A. Hooper
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
- School of Biological and Biomedical Sciences and Biophysical Sciences Institute. Durham University, Durham, United Kingdom
| | - Mark C. Shankey
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Louis P. Conway
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Martin Schröder
- School of Biological and Biomedical Sciences and Biophysical Sciences Institute. Durham University, Durham, United Kingdom
| | - David R. W. Hodgson
- Department of Chemistry and Biophysical Sciences Institute, Durham University, Durham, United Kingdom
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Korennykh AV, Korostelev AA, Egea PF, Finer-Moore J, Stroud RM, Zhang C, Shokat KM, Walter P. Structural and functional basis for RNA cleavage by Ire1. BMC Biol 2011; 9:47. [PMID: 21729333 PMCID: PMC3149027 DOI: 10.1186/1741-7007-9-47] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 07/06/2011] [Indexed: 11/12/2022] Open
Abstract
Background The unfolded protein response (UPR) controls the protein folding capacity of the endoplasmic reticulum (ER). Central to this signaling pathway is the ER-resident bifunctional transmembrane kinase/endoribonuclease Ire1. The endoribonuclease (RNase) domain of Ire1 initiates a non-conventional mRNA splicing reaction, leading to the production of a transcription factor that controls UPR target genes. The mRNA splicing reaction is an obligatory step of Ire1 signaling, yet its mechanism has remained poorly understood due to the absence of substrate-bound crystal structures of Ire1, the lack of structural similarity between Ire1 and other RNases, and a scarcity of quantitative enzymological data. Here, we experimentally define the active site of Ire1 RNase and quantitatively evaluate the contribution of the key active site residues to catalysis. Results This analysis and two new crystal structures suggest that Ire1 RNase uses histidine H1061 and tyrosine Y1043 as the general acid-general base pair contributing ≥ 7.6 kcal/mol and 1.4 kcal/mol to transition state stabilization, respectively, and asparagine N1057 and arginine R1056 for coordination of the scissile phosphate. Investigation of the stem-loop recognition revealed that additionally to the stem-loops derived from the classic Ire1 substrates HAC1 and Xbp1 mRNA, Ire1 can site-specifically and rapidly cleave anticodon stem-loop (ASL) of unmodified tRNAPhe, extending known substrate specificity of Ire1 RNase. Conclusions Our data define the catalytic center of Ire1 RNase and suggest a mechanism of RNA cleavage: each RNase monomer apparently contains a separate catalytic apparatus for RNA cleavage, whereas two RNase subunits contribute to RNA stem-loop docking. Conservation of the key residues among Ire1 homologues suggests that the mechanism elucidated here for yeast Ire1 applies to Ire1 in metazoan cells, and to the only known Ire1 homologue RNase L.
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Affiliation(s)
- Alexei V Korennykh
- Howard Hughes Medical Institute, University Of California, San Francisco, Genentech Hall, 600-16th Street, San Francisco, CA 94158, USA.
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Gesner EM, Schellenberg MJ, Garside EL, George MM, Macmillan AM. Recognition and maturation of effector RNAs in a CRISPR interference pathway. Nat Struct Mol Biol 2011; 18:688-92. [PMID: 21572444 DOI: 10.1038/nsmb.2042] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2011] [Accepted: 02/17/2011] [Indexed: 01/24/2023]
Abstract
In bacteria and archaea, small RNAs derived from clustered, regularly interspaced, short palindromic repeat (CRISPR) loci are involved in an adaptable and heritable gene-silencing pathway. Resistance to phage infection is conferred by the incorporation of short invading DNA sequences into the genome as CRISPR spacer elements separated by short repeat sequences. Processing of long primary transcripts (pre-crRNAs) containing these repeats by an RNA endonuclease generates the mature effector RNAs that interfere with phage gene expression. Here we describe structural and functional analyses of the Thermus thermophilus CRISPR Cse3 endonuclease. High-resolution X-ray structures of Cse3 bound to repeat RNAs model both the pre- and post-cleavage complexes associated with processing the pre-crRNA. These structures establish the molecular basis of a specific CRISPR RNA recognition and suggest the mechanism for generation of effector RNAs responsible for gene silencing.
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Affiliation(s)
- Emily M Gesner
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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Carte J, Pfister NT, Compton MM, Terns RM, Terns MP. Binding and cleavage of CRISPR RNA by Cas6. RNA (NEW YORK, N.Y.) 2010; 16:2181-8. [PMID: 20884784 PMCID: PMC2957057 DOI: 10.1261/rna.2230110] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The CRISPR-Cas system provides many prokaryotes with acquired resistance to viruses and other mobile genetic elements. The core components of this defense system are small, host-encoded prokaryotic silencing (psi)RNAs and Cas (CRISPR-associated) proteins. Invader-derived sequences within the psiRNAs guide Cas effector proteins to recognize and silence invader nucleic acids. Critical for CRISPR-Cas defense is processing of the psiRNAs from the primary transcripts of the host CRISPR (clustered regularly interspaced short palindromic repeat) locus. Cas6, a previously identified endoribonuclease present in a wide range of prokaryotes with the CRISPR-Cas system, binds and cleaves within the repeat sequences that separate the individual invader targeting elements in the CRISPR locus transcript. In the present study, we investigated several key aspects of the mechanism of function of Cas6 in psiRNA biogenesis. RNA footprinting reveals that Pyrococcus furiosus Cas6 binds to a 7-nt (nucleotide) sequence near the 5' end of the CRISPR RNA repeat sequence, 14 nt upstream of the Cas6 cleavage site. In addition, analysis of the cleavage activity of P. furiosus Cas6 proteins with mutations at conserved residues suggests that a triad comprised of Tyr31, His46, and Lys52 plays a critical role in catalysis, consistent with a possible general acid-base RNA cleavage mechanism for Cas6. Finally, we show that P. furiosus Cas6 remains stably associated with its cleavage products, suggesting additional roles for Cas6 in psiRNA biogenesis.
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Affiliation(s)
- Jason Carte
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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Abstract
Nucleases cleave the phosphodiester bonds of nucleic acids and may be endo or exo, DNase or RNase, topoisomerases, recombinases, ribozymes, or RNA splicing enzymes. In this review, I survey nuclease activities with known structures and catalytic machinery and classify them by reaction mechanism and metal-ion dependence and by their biological function ranging from DNA replication, recombination, repair, RNA maturation, processing, interference, to defense, nutrient regeneration or cell death. Several general principles emerge from this analysis. There is little correlation between catalytic mechanism and biological function. A single catalytic mechanism can be adapted in a variety of reactions and biological pathways. Conversely, a single biological process can often be accomplished by multiple tertiary and quaternary folds and by more than one catalytic mechanism. Two-metal-ion-dependent nucleases comprise the largest number of different tertiary folds and mediate the most diverse set of biological functions. Metal-ion-dependent cleavage is exclusively associated with exonucleases producing mononucleotides and endonucleases that cleave double- or single-stranded substrates in helical and base-stacked conformations. All metal-ion-independent RNases generate 2',3'-cyclic phosphate products, and all metal-ion-independent DNases form phospho-protein intermediates. I also find several previously unnoted relationships between different nucleases and shared catalytic configurations.
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Abstract
tRNA biology has come of age, revealing an unprecedented level of understanding and many unexpected discoveries along the way. This review highlights new findings on the diverse pathways of tRNA maturation, and on the formation and function of a number of modifications. Topics of special focus include the regulation of tRNA biosynthesis, quality control tRNA turnover mechanisms, widespread tRNA cleavage pathways activated in response to stress and other growth conditions, emerging evidence of signaling pathways involving tRNA and cleavage fragments, and the sophisticated intracellular tRNA trafficking that occurs during and after biosynthesis.
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Affiliation(s)
- Eric M Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA.
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