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Hoolehan W, Harris JC, Rodgers KK. Molecular Mechanisms of DNA Sequence Selectivity in V(D)J Recombination. ACS OMEGA 2023; 8:34206-34214. [PMID: 37779976 PMCID: PMC10536018 DOI: 10.1021/acsomega.3c05601] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/07/2023] [Indexed: 10/03/2023]
Abstract
Antigen receptor (AgR) diversity is central to the ability of adaptive immunity in jawed vertebrates to protect against pathogenic agents. The production of highly diverse AgR repertoires is initiated during B and T cell lymphopoiesis by V(D)J recombination, which assembles the receptor genes from component gene segments in a cut-and-paste recombination reaction. Recombination activating proteins, RAG1 and RAG2 (RAG1/2), catalyze V(D)J recombination by cleaving adjacent to recombination signal sequences (RSSs) that flank AgR gene segments. Previous studies defined the consensus RSS as containing conserved heptamer and nonamer sequences separated by a less conserved 12 or 23 base-pair spacer sequence. However, many RSSs deviate from the consensus sequence, and the molecular mechanism for semiselective V(D)J recombination specificity is unknown. The modulation of chromatin structure during V(D)J recombination is essential in the formation of diverse AgRs in adaptive immunity while also reducing the likelihood for off-target recombination events that can result in chromosomal aberrations and genomic instability. Here we review what is presently known regarding mechanisms that facilitate assembly of RAG1/2 with RSSs, the ensuing conformational changes required for DNA cleavage activity, and how the readout of the RSS sequence affects reaction efficiency.
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Affiliation(s)
- Walker Hoolehan
- Department
of Biochemistry and Molecular Biology, Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Justin C. Harris
- Department
of Biochemistry and Molecular Biology, Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Karla K. Rodgers
- Department
of Biochemistry and Molecular Biology, Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
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Braams M, Pike-Overzet K, Staal FJT. The recombinase activating genes: architects of immune diversity during lymphocyte development. Front Immunol 2023; 14:1210818. [PMID: 37497222 PMCID: PMC10367010 DOI: 10.3389/fimmu.2023.1210818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 06/19/2023] [Indexed: 07/28/2023] Open
Abstract
The mature lymphocyte population of a healthy individual has the remarkable ability to recognise an immense variety of antigens. Instead of encoding a unique gene for each potential antigen receptor, evolution has used gene rearrangements, also known as variable, diversity, and joining gene segment (V(D)J) recombination. This process is critical for lymphocyte development and relies on recombination-activating genes-1 (RAG1) and RAG2, here collectively referred to as RAG. RAG serves as powerful genome editing tools for lymphocytes and is strictly regulated to prevent dysregulation. However, in the case of dysregulation, RAG has been implicated in cases of cancer, autoimmunity and severe combined immunodeficiency (SCID). This review examines functional protein domains and motifs of RAG, describes advances in our understanding of the function and (dys)regulation of RAG, discuss new therapeutic options, such as gene therapy, for RAG deficiencies, and explore in vitro and in vivo methods for determining RAG activity and target specificity.
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Affiliation(s)
- Merijn Braams
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
| | - Karin Pike-Overzet
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
| | - Frank J. T. Staal
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
- Novo Nordisk Foundation Centre for Stem Cell Medicine (reNEW), Leiden University Medical Centre, Leiden, Netherlands
- Department of Paediatrics, Leiden University Medical Centre, Leiden, Netherlands
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Hoolehan W, Harris JC, Byrum JN, Simpson DA, Rodgers K. An updated definition of V(D)J recombination signal sequences revealed by high-throughput recombination assays. Nucleic Acids Res 2022; 50:11696-11711. [PMID: 36370096 PMCID: PMC9723617 DOI: 10.1093/nar/gkac1038] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 10/18/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
Abstract
In the adaptive immune system, V(D)J recombination initiates the production of a diverse antigen receptor repertoire in developing B and T cells. Recombination activating proteins, RAG1 and RAG2 (RAG1/2), catalyze V(D)J recombination by cleaving adjacent to recombination signal sequences (RSSs) that flank antigen receptor gene segments. Previous studies defined the consensus RSS as containing conserved heptamer and nonamer sequences separated by a less conserved 12 or 23 base-pair spacer sequence. However, many RSSs deviate from the consensus sequence. Here, we developed a cell-based, massively parallel assay to evaluate V(D)J recombination activity on thousands of RSSs where the 12-RSS heptamer and adjoining spacer region contained randomized sequences. While the consensus heptamer sequence (CACAGTG) was marginally preferred, V(D)J recombination was highly active on a wide range of non-consensus sequences. Select purine/pyrimidine motifs that may accommodate heptamer unwinding in the RAG1/2 active site were generally preferred. In addition, while different coding flanks and nonamer sequences affected recombination efficiency, the relative dependency on the purine/pyrimidine motifs in the RSS heptamer remained unchanged. Our results suggest RAG1/2 specificity for RSS heptamers is primarily dictated by DNA structural features dependent on purine/pyrimidine pattern, and to a lesser extent, RAG:RSS base-specific interactions.
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Affiliation(s)
- Walker Hoolehan
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Justin C Harris
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jennifer N Byrum
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Destiny A Simpson
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Karla K Rodgers
- To whom correspondence should be addressed. Tel: +1 405 271 2227 (Ext 61248);
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Christie SM, Fijen C, Rothenberg E. V(D)J Recombination: Recent Insights in Formation of the Recombinase Complex and Recruitment of DNA Repair Machinery. Front Cell Dev Biol 2022; 10:886718. [PMID: 35573672 PMCID: PMC9099191 DOI: 10.3389/fcell.2022.886718] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
V(D)J recombination is an essential mechanism of the adaptive immune system, producing a diverse set of antigen receptors in developing lymphocytes via regulated double strand DNA break and subsequent repair. DNA cleavage is initiated by the recombinase complex, consisting of lymphocyte specific proteins RAG1 and RAG2, while the repair phase is completed by classical non-homologous end joining (NHEJ). Many of the individual steps of this process have been well described and new research has increased the scale to understand the mechanisms of initiation and intermediate stages of the pathway. In this review we discuss 1) the regulatory functions of RAGs, 2) recruitment of RAGs to the site of recombination and formation of a paired complex, 3) the transition from a post-cleavage complex containing RAGs and cleaved DNA ends to the NHEJ repair phase, and 4) the potential redundant roles of certain factors in repairing the break. Regulatory (non-core) domains of RAGs are not necessary for catalytic activity, but likely influence recruitment and stabilization through interaction with modified histones and conformational changes. To form long range paired complexes, recent studies have found evidence in support of large scale chromosomal contraction through various factors to utilize diverse gene segments. Following the paired cleavage event, four broken DNA ends must now make a regulated transition to the repair phase, which can be controlled by dynamic conformational changes and post-translational modification of the factors involved. Additionally, we examine the overlapping roles of certain NHEJ factors which allows for prevention of genomic instability due to incomplete repair in the absence of one, but are lethal in combined knockouts. To conclude, we focus on the importance of understanding the detail of these processes in regards to off-target recombination or deficiency-mediated clinical manifestations.
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Affiliation(s)
- Shaun M. Christie
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
| | - Carel Fijen
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
| | - Eli Rothenberg
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
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Shi B, Dong X, Ma Q, Sun S, Ma L, Yu J, Wang X, Pan J, He X, Su D, Yao X. The Usage of Human IGHJ Genes Follows a Particular Non-random Selection: The Recombination Signal Sequence May Affect the Usage of Human IGHJ Genes. Front Genet 2020; 11:524413. [PMID: 33363565 PMCID: PMC7753069 DOI: 10.3389/fgene.2020.524413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 11/06/2020] [Indexed: 12/02/2022] Open
Abstract
The formation of the B cell receptor (BCR) heavy chain variable region is derived from the germline V(D)J gene rearrangement according to the “12/23” rule and the “beyond 12/23” rule. The usage frequency of each V(D)J gene in the peripheral BCR repertoires is related to the initial recombination, self-tolerance selection, and the clonal proliferative response. However, their specific differences and possible mechanisms are still unknown. We analyzed in-frame and out-of-frame BCR-H repertoires from human samples with normal physiological and various pathological conditions by high-throughput sequencing. Our results showed that IGHJ gene frequency follows a similar pattern which is previously known, where IGHJ4 is used at high frequency (>40%), IGHJ6/IGHJ3/IGHJ5 is used at medium frequencies (10∼20%), and IGH2/IGHJ1 is used at low frequency (<4%) under whether normal physiological or various pathological conditions. However, our analysis of the recombination signal sequences suggested that the conserved non-amer and heptamer and certain 23 bp spacer length may affect the initial IGHD-IGHJ recombination, which results in different frequencies of IGHJ genes among the initial BCR-H repertoire. Based on this “initial repertoire,” we recommend that re-evaluation and further investigation are needed when analyzing the significance and mechanism of IGHJ gene frequency in self-tolerance selection and the clonal proliferative response.
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Affiliation(s)
- Bin Shi
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,School of Laboratory Medicine, Zunyi Medical University, Zunyi, China
| | - Xiaoheng Dong
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Qingqing Ma
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Suhong Sun
- Department of Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Long Ma
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Jiang Yu
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xiaomei Wang
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Juan Pan
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xiaoyan He
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Danhua Su
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
| | - Xinsheng Yao
- Department of Immunology, Center of Immunomolecular Engineering, Innovation & Practice Base for Graduate Students Education, Zunyi Medical University, Zunyi, China
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Ireland WT, Beeler SM, Flores-Bautista E, McCarty NS, Röschinger T, Belliveau NM, Sweredoski MJ, Moradian A, Kinney JB, Phillips R. Deciphering the regulatory genome of Escherichia coli, one hundred promoters at a time. eLife 2020; 9:e55308. [PMID: 32955440 PMCID: PMC7567609 DOI: 10.7554/elife.55308] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 09/18/2020] [Indexed: 01/28/2023] Open
Abstract
Advances in DNA sequencing have revolutionized our ability to read genomes. However, even in the most well-studied of organisms, the bacterium Escherichia coli, for ≈65% of promoters we remain ignorant of their regulation. Until we crack this regulatory Rosetta Stone, efforts to read and write genomes will remain haphazard. We introduce a new method, Reg-Seq, that links massively parallel reporter assays with mass spectrometry to produce a base pair resolution dissection of more than a E. coli promoters in 12 growth conditions. We demonstrate that the method recapitulates known regulatory information. Then, we examine regulatory architectures for more than 80 promoters which previously had no known regulatory information. In many cases, we also identify which transcription factors mediate their regulation. This method clears a path for highly multiplexed investigations of the regulatory genome of model organisms, with the potential of moving to an array of microbes of ecological and medical relevance.
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Affiliation(s)
- William T Ireland
- Department of Physics, California Institute of TechnologyPasadenaUnited States
| | - Suzannah M Beeler
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Emanuel Flores-Bautista
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Nicholas S McCarty
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Tom Röschinger
- Division of Chemistry and Chemical Engineering, California Institute of TechnologyPasadenaUnited States
| | - Nathan M Belliveau
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Michael J Sweredoski
- Proteome Exploration Laboratory, Division of Biology and Biological Engineering, Beckman Institute, California Institute of TechnologyPasadenaUnited States
| | - Annie Moradian
- Proteome Exploration Laboratory, Division of Biology and Biological Engineering, Beckman Institute, California Institute of TechnologyPasadenaUnited States
| | - Justin B Kinney
- Simons Center for Quantitative Biology, Cold Spring Harbor LaboratoryCold Spring HarborUnited States
| | - Rob Phillips
- Department of Physics, California Institute of TechnologyPasadenaUnited States
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
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