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Sapkota K, Lucas JK, Faulkner JW, Lichte MF, Guo YL, Burke DH, Huang F. Post-transcriptional capping generates coenzyme A-linked RNA. RNA Biol 2024; 21:1-12. [PMID: 38032240 PMCID: PMC10761072 DOI: 10.1080/15476286.2023.2288740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2023] [Indexed: 12/01/2023] Open
Abstract
NAD can be inserted co-transcriptionally via non-canonical initiation to form NAD-RNA. However, that mechanism is unlikely for CoA-linked RNAs due to low intracellular concentration of the required initiator nucleotide, 3'-dephospho-CoA (dpCoA). We report here that phosphopantetheine adenylyltransferase (PPAT), an enzyme of CoA biosynthetic pathway, accepts RNA transcripts as its acceptor substrate and transfers 4'-phosphopantetheine to yield CoA-RNA post-transcriptionally. Synthetic natural (RNAI) and small artificial RNAs were used to identify the features of RNA that are needed for it to serve as PPAT substrate. RNAs with 4-10 unpaired nucleotides at the 5' terminus served as PPAT substrates, but RNAs having <4 unpaired nucleotides did not undergo capping. No capping was observed when the +1A was changed to G or when 5' triphosphate was removed by RNA pyrophosphohydrolase (RppH), suggesting the enzyme recognizes pppA-RNA as an ATP analog. PPAT binding affinities were equivalent for transcripts with +1A, +1 G, or 5'OH (+1A), indicating that productive enzymatic recognition is driven more by local positioning effects than by overall binding affinity. Capping rates were independent of the number of unpaired nucleotides in the range of 4-10 nucleotides. Capping was strongly inhibited by ATP, reducing CoA-RNA production ~70% when equimolar ATP and substrate RNA were present. Dual bacterial expression of candidate RNAs with different 5' structures followed by CoA-RNA CaptureSeq revealed 12-fold enrichment of the better PPAT substrate, consistent with in vivo CoA-capping of RNA transcripts by PPAT. These results suggest post-transcriptional RNA capping as a possible mechanism for the biogenesis of CoA-RNAs in bacteria.
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Affiliation(s)
- Krishna Sapkota
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Jordyn K. Lucas
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
- Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
| | - Jarrett W. Faulkner
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Matt F. Lichte
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
- Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
| | - Yan-Lin Guo
- Department of Cell and Molecular Biology, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Donald H. Burke
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
- Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
- Department of Molecular Microbiology & Immunology, University of Missouri, Columbia, MO, USA
| | - Faqing Huang
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS, USA
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Thiophosphate Analogs of Coenzyme A and Its Precursors—Synthesis, Stability, and Biomimetic Potential. Biomolecules 2022; 12:biom12081065. [PMID: 36008959 PMCID: PMC9405834 DOI: 10.3390/biom12081065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 02/05/2023] Open
Abstract
Coenzyme A (CoA) is ubiquitous and essential for key cellular processes in any living organism. Primary degradation of CoA occurs by enzyme-mediated pyrophosphate hydrolysis intracellularly and extracellularly to form adenosine 3’,5’-diphosphate and 4’-phosphopantetheine (PPanSH). The latter can be recycled for intracellular synthesis of CoA. Impairments in the CoA biosynthetic pathway are linked to a severe form of neurodegeneration with brain iron accumulation for which no disease-modifying therapy is available. Currently, exogenous administration of PPanSH is examined as a therapeutic intervention. Here, we describe biosynthetic access to thiophosphate analogs of PPanSH, 3′-dephospho-CoA, and CoA. The stabilizing effect of thiophosphate modifications toward degradation by extracellular and peroxisomal enzymes was studied in vitro. Experiments in a CoA-deficient cell model suggest a biomimetic potential of the PPanSH thiophosphate analog PSPanSH (C1). According to our findings, the administration of PSPanSH may provide an alternative approach to support intracellular CoA-dependent pathways.
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