7v9u

Structural highlights

Function

RT86_ECOLX Reverse transcriptase (RT) component of antiviral defense system retron Ec86, composed of a non-coding RNA (ncRNA), a ribosyltransferase/DNA-binding protein and this RT. Expression of the 3-gene retron confers protection against bacteriophage T5. At multiplicity of infection (MOI) of 0.02 cultures grow normally when infected with T5 without collapsing, at MOI 2 cultures enter growth stasis (PubMed:33157039). Responsible for synthesis of msDNA (a branched molecule with RNA linked by a 2',5'-phosphodiester bond to ssDNA). The retron transcript serves as primer (from a conserved internal G residue) and template for the reaction, and codes for the RT (PubMed:10531319, PubMed:2466573). Recognizes only its cognate RNA as a primer template (PubMed:10531319). Overexpression of the ncRNA and RT (without the ribosyltransferase), which leads to increased levels of msDNA, is mutagenic in vivo (PubMed:7885227). This may be due to a mismatch in the msDNA stem which binds and sequesters MutS and/or MutL (Probable).^{[1] [2] [3] [4] [5]}

References

1. ↑ Inouye S, Hsu MY, Xu A, Inouye M. Highly specific recognition of primer RNA structures for 2'-OH priming reaction by bacterial reverse transcriptases. J Biol Chem. 1999 Oct 29;274(44):31236-44. doi: 10.1074/jbc.274.44.31236. PMID:10531319 doi:http://dx.doi.org/10.1074/jbc.274.44.31236
2. ↑ Lim D, Maas WK. Reverse transcriptase-dependent synthesis of a covalently linked, branched DNA-RNA compound in E. coli B. Cell. 1989 Mar 10;56(5):891-904. PMID:2466573
3. ↑ Millman A, Bernheim A, Stokar-Avihail A, Fedorenko T, Voichek M, Leavitt A, Oppenheimer-Shaanan Y, Sorek R. Bacterial Retrons Function In Anti-Phage Defense. Cell. 2020 Dec 10;183(6):1551-1561.e12. doi: 10.1016/j.cell.2020.09.065. Epub, 2020 Nov 5. PMID:33157039 doi:http://dx.doi.org/10.1016/j.cell.2020.09.065
4. ↑ Maas WK, Wang C, Lima T, Zubay G, Lim D. Multicopy single-stranded DNAs with mismatched base pairs are mutagenic in Escherichia coli. Mol Microbiol. 1994 Nov;14(3):437-41. doi: 10.1111/j.1365-2958.1994.tb02178.x. PMID:7885227 doi:http://dx.doi.org/10.1111/j.1365-2958.1994.tb02178.x
5. ↑ Maas WK, Wang C, Lima T, Zubay G, Lim D. Multicopy single-stranded DNAs with mismatched base pairs are mutagenic in Escherichia coli. Mol Microbiol. 1994 Nov;14(3):437-41. doi: 10.1111/j.1365-2958.1994.tb02178.x. PMID:7885227 doi:http://dx.doi.org/10.1111/j.1365-2958.1994.tb02178.x