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Oh J, Shan Z, Hoshika S, Xu J, Chong J, Benner SA, Lyumkis D, Wang D. A unified Watson-Crick geometry drives transcription of six-letter expanded DNA alphabets by E. coli RNA polymerase. Nat Commun 2023; 14:8219. [PMID: 38086811 PMCID: PMC10716388 DOI: 10.1038/s41467-023-43735-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 11/17/2023] [Indexed: 12/18/2023] Open
Abstract
Artificially Expanded Genetic Information Systems (AEGIS) add independently replicable unnatural nucleotide pairs to the natural G:C and A:T/U pairs found in native DNA, joining the unnatural pairs through alternative modes of hydrogen bonding. Whether and how AEGIS pairs are recognized and processed by multi-subunit cellular RNA polymerases (RNAPs) remains unknown. Here, we show that E. coli RNAP selectively recognizes unnatural nucleobases in a six-letter expanded genetic system. High-resolution cryo-EM structures of three RNAP elongation complexes containing template-substrate UBPs reveal the shared principles behind the recognition of AEGIS and natural base pairs. In these structures, RNAPs are captured in an active state, poised to perform the chemistry step. At this point, the unnatural base pair adopts a Watson-Crick geometry, and the trigger loop is folded into an active conformation, indicating that the mechanistic principles underlying recognition and incorporation of natural base pairs also apply to AEGIS unnatural base pairs. These data validate the design philosophy of AEGIS unnatural basepairs. Further, we provide structural evidence supporting a long-standing hypothesis that pair mismatch during transcription occurs via tautomerization. Together, our work highlights the importance of Watson-Crick complementarity underlying the design principles of AEGIS base pair recognition.
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Affiliation(s)
- Juntaek Oh
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Zelin Shan
- The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution, 13709 Progress Blvd Box 7, Alachua, FL, 32615, USA
| | - Jun Xu
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Jenny Chong
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, 13709 Progress Blvd Box 7, Alachua, FL, 32615, USA.
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute 10550 N Torrey Pines Road, La Jolla, CA, 92037, USA.
- Graduate School of Biological Sciences, Section of Molecular Biology, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Dong Wang
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA.
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, 92093, USA.
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA.
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Thomas CA, Craig JM, Hoshika S, Brinkerhoff H, Huang JR, Abell SJ, Kim HC, Franzi MC, Carrasco JD, Kim HJ, Smith DC, Gundlach JH, Benner SA, Laszlo AH. Assessing Readability of an 8-Letter Expanded Deoxyribonucleic Acid Alphabet with Nanopores. J Am Chem Soc 2023; 145:8560-8568. [PMID: 37036666 DOI: 10.1021/jacs.3c00829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Chemists have now synthesized new kinds of DNA that add nucleotides to the four standard nucleotides (guanine, adenine, cytosine, and thymine) found in standard Terran DNA. Such "artificially expanded genetic information systems" are today used in molecular diagnostics; to support directed evolution to create medically useful receptors, ligands, and catalysts; and to explore issues related to the early evolution of life. Further applications are limited by the inability to directly sequence DNA containing nonstandard nucleotides. Nanopore sequencing is well-suited for this purpose, as it does not require enzymatic synthesis, amplification, or nucleotide modification. Here, we take the first steps to realize nanopore sequencing of an 8-letter "hachimoji" expanded DNA alphabet by assessing its nanopore signal range using the MspA (Mycobacterium smegmatis porin A) nanopore. We find that hachimoji DNA exhibits a broader signal range in nanopore sequencing than standard DNA alone and that hachimoji single-base substitutions are distinguishable with high confidence. Because nanopore sequencing relies on a molecular motor to control the motion of DNA, we then assessed the compatibility of the Hel308 motor enzyme with nonstandard nucleotides by tracking the translocation of single Hel308 molecules along hachimoji DNA, monitoring the enzyme kinetics and premature enzyme dissociation from the DNA. We find that Hel308 is compatible with hachimoji DNA but dissociates more frequently when walking over C-glycoside nucleosides, compared to N-glycosides. C-glycocide nucleosides passing a particular site within Hel308 induce a higher likelihood of dissociation. This highlights the need to optimize nanopore sequencing motors to handle different glycosidic bonds. It may also inform designs of future alternative DNA systems that can be sequenced with existing motors and pores.
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Affiliation(s)
- Christopher A Thomas
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jonathan M Craig
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution, Alachua, Florida 32615, United States
| | - Henry Brinkerhoff
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jesse R Huang
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Sarah J Abell
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Hwanhee C Kim
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Michaela C Franzi
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jessica D Carrasco
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Hyo-Joong Kim
- Foundation for Applied Molecular Evolution, Alachua, Florida 32615, United States
| | - Drew C Smith
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jens H Gundlach
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, Alachua, Florida 32615, United States
| | - Andrew H Laszlo
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
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Shukla MS, Hoshika S, Benner SA, Georgiadis MM. Crystal structures of 'ALternative Isoinformational ENgineered' DNA in B-form. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220028. [PMID: 36633282 PMCID: PMC9835606 DOI: 10.1098/rstb.2022.0028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/20/2022] [Indexed: 01/13/2023] Open
Abstract
The first structural model of duplex DNA reported in 1953 by Watson & Crick presented the double helix in B-form, the form that genomic DNA exists in much of the time. Thus, artificial DNA seeking to mimic the properties of natural DNA should also be able to adopt B-form. Using a host-guest system in which Moloney murine leukemia virus reverse transcriptase serves as the host and DNA as the guests, we determined high-resolution crystal structures of three complexes including 5'-CTTBPPBBSSZZSAAG, 5'-CTTSSPBZPSZBBAAG and 5'-CTTZZPBSBSZPPAAG with 10 consecutive unnatural nucleobase pairs in B-form within self-complementary 16 bp duplex oligonucleotides. We refer to this ALternative Isoinformational ENgineered (ALIEN) genetic system containing two nucleobase pairs (P:Z, pairing 2-amino-imidazo-[1,2-a]-1,3,5-triazin-(8H)-4-one with 6-amino-5-nitro-(1H)-pyridin-2-one, and B:S, 6-amino-4-hydroxy-5-(1H)-purin-2-one with 3-methyl-6-amino-pyrimidin-2-one) as ALIEN DNA. We characterized both position- and sequence-specific helical, nucleobase pair and dinucleotide step parameters of P:Z and B:S pairs in the context of B-form DNA. We conclude that ALIEN DNA exhibits structural features that vary with sequence. Further, Z can participate in alternative stacking modes within a similar sequence context as captured in two different structures. This finding suggests that ALIEN DNA may have a larger repertoire of B-form structures than natural DNA. This article is part of the theme issue 'Reactivity and mechanism in chemical and synthetic biology'.
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Affiliation(s)
- Madhura S. Shukla
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution, 13709 Progress Boulevard, no. 7, Alachua, FL 32615, USA
| | - Steven A. Benner
- Foundation for Applied Molecular Evolution, 13709 Progress Boulevard, no. 7, Alachua, FL 32615, USA
| | - Millie M. Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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