Will scientists be able to assemble a ribosome in vitro, composed entirely of synthetic proteins and RNA, without the use of cell-derived materials by 2030?

Started Jul 01, 2025 04:00AM UTC
Closing Jul 01, 2026 04:00AM UTC
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Ribosomes are complex molecular machines responsible for protein synthesis, consisting of two subunits (one small and one large subunit) that combine during protein synthesis (Molecular Biology of the Cell, National Human Genome Research Institute, Khan Academy). The subunits are both composed of ribosomal RNA (rRNA) and proteins. 

A key step in the creation of mirror life would be the creation of a mirror-version ribosome. The creation of a mirror ribosome is unlikely to be feasible before protocols for the synthesis and assembly of 100% synthetic natural-chirality ribosomes is achieved.

To date, this has only been accomplished for the small (30S) ribosomal subunit. In 2020, scientists at the RIKEN Center for Biosystems Dynamics Research demonstrated that individually synthesized small subunit ribosomal proteins and in vitro transcribed 16S rRNA could assemble with purified large (50S) ribosomal subunits in a modified PURE system, forming functional ribosomes capable of synthesizing sfGFP (Nature). Note that the PURE system does contain tRNAs isolated from cells, but these tRNAs are not involved in ribosome assembly, so it is still considered cell-free assembly for the purposes of this question.

However, the large subunit is significantly more complex than the small subunit, as it is roughly twice the size of the small subunit and it contains a much larger rRNA component that forms the site for peptide bond formation. This rRNA also requires extensive post-translation modification to function, which is difficult to mimic via synthetic RNA synthesis. Thus, total synthesis and assembly of the large subunit, without the need for native ribosomal components from native cells, has yet to be achieved.

Resolution Criteria: 
This is an unscored question that closes for forecasting on 1 July 2026. Although this is an unscored question, we outline the theoretical resolution criteria here.

This question will resolve as “Yes” if, by 31 December 2030, a peer-reviewed scientific publication or a scientific preprint reports the successful in vitro synthesis and assembly of a functional ribosome that meets all of the following criteria:
  • Complete synthesis: All ribosomal proteins must be chemically synthesized or produced recombinantly, not extracted from natural cells. All ribosomal RNAs must be chemically synthesized or produced by in vitro transcription, not extracted from living cells.
  • Self-assembly: The components are assembled in vitro in a fully defined chemical environment and do not contain any undefined cellular mixtures. For example, the use of crude or fractionated cell lysates or extracts (e.g. S30 or S15) would not qualify, but a reconstituted cell-free protein synthesis system (e.g. PUREfrex2.0) would qualify, provided it does not contribute cell-derived ribosomes to the assembly process. 
  • Functional activity: The assembled 70S ribosome demonstrates measurable peptidyl transferase activity (the ability to catalyze peptide bond formation).
Partial assembly, assembly requiring natural cellular machinery, or assembly using components extracted from natural ribosomes will not qualify for a “Yes” resolution.
Question clarification
Issued on 08/04/25 07:21pm

The background information previously mentioned that scientists at the Weizmann Institute of Science achieved autonomous synthesis and assembly of the small ribosomal subunit (30S) using only synthetic components. However, upon further review, the method required the PURE system to provide cell-derived components (70S ribosomes isolated from E. coli), which means it did not meet our self-assembly criteria. We have replaced that paragraph with information about research from the RIKEN Center for Biosystems Dynamics Research which showed that the individual components of the 30S ribosome could assemble and produce a functional 70S ribosome in a modified PURE system that only provided a suitable environment for ribosomal assembly and functional testing. The presence of cell-derived tRNAs in this instance does not disqualify, as they do not participate in ribosomal assembly.

We also updated the self-assembly portion of the resolution criteria to clarify that PURE systems that provide 70S ribosomes isolated from living cells which are used in the assembly process (such as in the Weizmann case) would not count, while PURE systems without 70S ribosomes (such as in the RIKEN case) would count.

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