Chinese Journal of Catalysis ›› 2026, Vol. 80: 92-112.DOI: 10.1016/S1872-2067(25)64860-1
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Shiyi Chea,b, Zhengjun Lib, Zhiguo Sub, Zhikao Lia, Aibing Yua, Minsu Liua,c,*(
), Songping Zhangb,*(
)
Received:2025-06-09
Accepted:2025-09-06
Online:2026-01-18
Published:2026-01-05
Contact:
Minsu Liu, Songping Zhang
About author:Minsu Liu (Monash University) is a senior research fellow at Monash Suzhou Research Institute and a senior lecturer at Department of Materials Science and Engineering, Monash University. He has obtained his B.E. (Hon. 1) and Ph.D. from the University of New South Wales (Australia) and Monash University (Australia), respectively. Before joining Monash, Dr. Liu worked as postdoctoral fellow at Monash University (2017‒2018) and Tsinghua University (2018‒2020). Dr. Minsu Liu is expertise in the research of nanofabrication, 2D materials, self-assembly, and thermal management. He has published more than 50 peer-reviewed journal articles with more than 2000 citations, and applied/granted more than 50 patents.Supported by:Shiyi Che, Zhengjun Li, Zhiguo Su, Zhikao Li, Aibing Yu, Minsu Liu, Songping Zhang. Engineering of enzymatic modules for mRNA manufacturing: Advances in catalytic regulation and process integration[J]. Chinese Journal of Catalysis, 2026, 80: 92-112.
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URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(25)64860-1
Fig. 1. Flow chart for manufacturing of capped mRNA from plasmid preparation to enzymatic capping, which includes four typical catalytic reaction modules. Module 1: Circular plasmid DNA is linearized by the restriction endonuclease (REase). Module 2: The linearized plasmid DNA serves as the template for IVT synthesis of mRNA catalyzed by T7 RNAP along with PPase. Module 3: Enzymatic capping of mRNA by vaccinia capping enzyme (VCE) and 2’-O-methyltransferase (2’-O-MTase) to generate the cap-1 mRNA. Module 4: A panel of nucleases mainly including RNase A, DNase I, RNase III, and RNase R, which are employed to degrade the residual RNA in the plasmid, residual plasmid DNA and dsRNA in the IVT mRNA, linear precursor RNA impurities in the circular RNA, respectively. Between each module, chromatographic processes are integrated to ensure intermediate and final product purity.
Fig. 3. IVT reaction catalyzed by T7 RNAP and PPase. (A) Mechanism of IVT reaction for mRNA synthesis: T7 RNAP catalysis, Mg2PPi byproduct formation and PPase catalysis. Conformational changes of initiation phase (PDB: 1QLN) (B) and elongation phase (PDB: 1H38) (C). (D) NTP insertion. Reprinted with permission from Ref. [37]. Copyright 2009, Elsevier. (E) RNA byproducts. (E-1) Incomplete RNA transcripts. (E-2) Intramolecular (cis) and intermolecular (trans) 3’extension. (E-3) Antisense RNA by promoter-less DNA. (E-4) Non-covalent mRNA aggregates.
Fig. 4. Enzyme engineering and co-immobilization of RNAP. (A) Thermophilic RNAP (G788A). (B) mRNA synthesis by psychrophilic Syn5 RNAP and VSW-3 RNAP. Reprinted with permission from Ref. [54]. Copyright 2022, Taylor & Francis. (C) RNAP for conformation transition (G47A and an extra C-terminal 884G). Reprinted with permission from Ref. [58]. Copyright 2023, Springer Nature. (D) Immobilized strategy for simultaneous tethering T7 RNAP and DNA template. (D-1) Tethering Strep-tag T7 RNAP and 5’-biotin nontemplate strand of DNA to Strep-TactinXT-coated magnetic beads. Reprinted with permission from Ref. [60]. Copyright 2021, Elsevier. (D-2) Tethering 5’-biotin template strand of DNA to streptavidin magnetic beads with promoter on the nontemplate strand linked HaloTag-T7 RNAP. Reprinted with permission from Ref. [61]. Copyright 2024, Oxford University Press.
| Regulation | Strategy | Impact | Condition | Ref. | |
|---|---|---|---|---|---|
| Enzyme engineering | thermophilic RNAP | reduced 3’extension dsRNA | high-temperature | [ | |
| psychrophilic RNAP | reduced 3’extension dsRNA | low-temperature | [ | ||
| P266L mutant | reduced abortive RNA | — | [ | ||
| S43Y mutant G47A + 884G mutant | reduced 3’extension dsRNA | — | [ | ||
| G47W mutant | reduced antisense dsRNA | — | [ | ||
| Co-immobilization | DNA was tethered with T7 RNAP to beads | reduced 3’extension dsRNA/Higher yield | high-salt | [ | |
| Using modified NTP | Ψ, m1Ψ, m5C, 5moU | reduced antisense dsRNA | — | [ | |
| increased ARCA/ m1Ψ | reduced immunogenicity | — | [ | ||
| Optimizing RNA sequence | -4 gap on the non-template strand of the DNA promoter | reduced 3’extension dsRNA/Higher yield | high-salt | [ | |
| additional AT-rich sequences at T7 promoter downstream | reduced abortive RNA and dsRNA/Higher yield | high-temperature | [ | ||
| Reaction process regulation | fed-batch strategy | higher yield | — | [ | |
| low ratio of Mg2+/NTP | reduced antisense dsRNA | — | [ | ||
| low UTP concentrations | reduced 3’extension dsRNA | — | [ | ||
| addition of urea or formamide | reduced 3’extension dsRNA | — | [ | ||
Table 1 In-process regulation strategies in the IVT module.
| Regulation | Strategy | Impact | Condition | Ref. | |
|---|---|---|---|---|---|
| Enzyme engineering | thermophilic RNAP | reduced 3’extension dsRNA | high-temperature | [ | |
| psychrophilic RNAP | reduced 3’extension dsRNA | low-temperature | [ | ||
| P266L mutant | reduced abortive RNA | — | [ | ||
| S43Y mutant G47A + 884G mutant | reduced 3’extension dsRNA | — | [ | ||
| G47W mutant | reduced antisense dsRNA | — | [ | ||
| Co-immobilization | DNA was tethered with T7 RNAP to beads | reduced 3’extension dsRNA/Higher yield | high-salt | [ | |
| Using modified NTP | Ψ, m1Ψ, m5C, 5moU | reduced antisense dsRNA | — | [ | |
| increased ARCA/ m1Ψ | reduced immunogenicity | — | [ | ||
| Optimizing RNA sequence | -4 gap on the non-template strand of the DNA promoter | reduced 3’extension dsRNA/Higher yield | high-salt | [ | |
| additional AT-rich sequences at T7 promoter downstream | reduced abortive RNA and dsRNA/Higher yield | high-temperature | [ | ||
| Reaction process regulation | fed-batch strategy | higher yield | — | [ | |
| low ratio of Mg2+/NTP | reduced antisense dsRNA | — | [ | ||
| low UTP concentrations | reduced 3’extension dsRNA | — | [ | ||
| addition of urea or formamide | reduced 3’extension dsRNA | — | [ | ||
Fig. 5. Reaction process regulation and model. (A-1) The fed-batch strategy with pH-controlled addition of KOH, NTP and Mg(OAc)2. Reprinted with permission from Ref. [78]. Copyright 1999, American Institute of Chemical Engineers. (A-2) The fed-batch strategy with at-line HPLC-monitored addition of NTPs and Mg2+. Reprinted with permission from Ref. [79]. Copyright 2023, Wiley. (B) Bayesian optimization approach with a robotic liquid handler to enable high-throughput algorithmic optimization. Reprinted with permission from Ref. [94]. Copyright 2024, American Chemical Society. (C) A new IVT reaction model reported by Stover et al. Reprinted with permission from Ref. [95]. Copyright 2024, Wiley.
Fig. 6. Conformation of (A) vaccinia capping enzyme (PDB: 4CKB) and (B) 2’-O-methyltransferase (PDB: 1AV6). (A-1) Domains and mRNA capping pathways in VCE [104]. (A-2) FigureTPase with a closed hydrophilic tunnel formed by eight β-barrels. (A-3) NTase domain with GTP-binding site and OB domain in GTase. (A-4) N7-MTase domain with SAM-binding site. Engineering in-process regulation strategies of immobilization of VCE and 2’-O-MTase (C), characterization of novel FCE and its comparison to VCE at different temperatures (Reprinted with permission from Ref. [107]. Copyright 2023, Cold Spring Harbor Laboratory Press) (D), and VCE catalysis with different GTP analogs: Chemical structure and capping efficiency (E). Reprinted with permission from Ref. [113]. Copyright 2023, Oxford University Press.
| Enzyme | Source | Type | Metal ions | Application |
|---|---|---|---|---|
| RNase A | Bovine pancreas | Endo- | independent | RNA removal in circular plasmid preparation |
| DNase I | Bovine pancreas | Endo- | Mg2+, Ca2+ | DNA removal after the IVT reaction |
| RNase III | E. coli | Endo- | Mg2+ | dsRNA removal after the IVT reaction |
| RNase R | E. coli | Exo- | Mg2+ | linear RNA precursor removal in circRNA purification |
Table 2 Summary of nucleases in mRNA manufacturing.
| Enzyme | Source | Type | Metal ions | Application |
|---|---|---|---|---|
| RNase A | Bovine pancreas | Endo- | independent | RNA removal in circular plasmid preparation |
| DNase I | Bovine pancreas | Endo- | Mg2+, Ca2+ | DNA removal after the IVT reaction |
| RNase III | E. coli | Endo- | Mg2+ | dsRNA removal after the IVT reaction |
| RNase R | E. coli | Exo- | Mg2+ | linear RNA precursor removal in circRNA purification |
Fig. 7. Nucleases conformation and engineering in mRNA manufacturing. (A-1) Interactions between RNase A (PDB: 3DXG) and RNase inhibitor (PDB: 4PEQ). (A-2) Immobilization of RNase A by macroporous monolithic support. (B) Adsorption of DNase I (PDB: 1DNK) by AuNP with a capping agent surface. (C) The homodimeric structure of E. coli RNase Ⅲ (PDB: 7R97). (D) Structure of E. coli RNase R. Reprinted with permission from Ref. [133]. Copyright 2017, Oxford University Press.
Fig. 8. Three strategies for process integration in mRNA manufacturing and their corresponding main characteristics and challenges. Briefly, the first strategy is integration between circular plasmid linearization and IVT modules (Modules 1 and 2), the second type is integration between IVT and capping modules (Modules 2 and 3), and the third type is reaction-separation coupling, which usually requires solid-phase-immobilized mRNA. These three reaction modules involved different reaction types of site cleavage, de novo synthesis and site modification, respectively.
Fig. 9. Integration between IVT and capping modules. (A) Co-transcription with cap analogs. (B) Fusion of T7 RNAP and FCE reported by Robb et al. [124]. (C) Continuous cascade reaction by integrated buffer reported by Nwokeoji et al. Reprinted with permission from Ref. [145]. Copyright 2023, American Chemical Society. (D) Continuous process control by digital twin reported by Helgers et al. Reprinted with permission from Ref. [146]. Copyright 2021, MDPI.
| Enzyme | Condition | ||||||
|---|---|---|---|---|---|---|---|
| Temperature | pH | Buffer | Mg²⁺ | spermidine | DTT | Na⁺/K⁺/Cl- | |
| T7 RNAP | 37 °C | 7.5-8.0 | Tris-HCl | 10-50 mmol/L | 1-2 mmol/L, promote DNA condensation | 1-10 mmol/L | inhibitory at concentrations > 0.1 mol/L |
| VCE | 37-45 °C | 1 mmol/L | — | 1 mmol/L | |||
| 2’-O-MTase | 45 °C | 1 mmol/L | — | 1 mmol/L | |||
Table 3 General conditions of the enzymatic reactions catalyzed by T7 RNAP, VCE and 2’-O-MTase.
| Enzyme | Condition | ||||||
|---|---|---|---|---|---|---|---|
| Temperature | pH | Buffer | Mg²⁺ | spermidine | DTT | Na⁺/K⁺/Cl- | |
| T7 RNAP | 37 °C | 7.5-8.0 | Tris-HCl | 10-50 mmol/L | 1-2 mmol/L, promote DNA condensation | 1-10 mmol/L | inhibitory at concentrations > 0.1 mol/L |
| VCE | 37-45 °C | 1 mmol/L | — | 1 mmol/L | |||
| 2’-O-MTase | 45 °C | 1 mmol/L | — | 1 mmol/L | |||
Fig. 10. Reaction-separation coupling for mRNA manufacturing. (A) The combined IVT-solid-phase reaction-separation approach published by Liu et al. Reprinted with permission from Ref. [151]. Copyright 2015, Springer Nature. (B) The chemoenzymatic method published by Thillier et al. Reprinted with permission from Ref. [152]. Copyright 2012, Cold Spring Harbor Laboratory Press. (C) The on‐column capping of poly dT-tethered mRNA proposed by Che et al. Reprinted with permission from Ref. [153]. Copyright 2024, Wiley.
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