5g5t

Structural highlights

Function

AGO_METJA A DNA-guided ssDNA endonuclease that may play a role in defense against invading genetic elements. Uses short ssDNA sequences as guides (gDNA) to bind complementary target strands, resulting in slicing of the target DNA (tDNA) (PubMed:24442234, PubMed:27741323, PubMed:28319081, PubMed:28319084). Endonucleolytically cleaves tDNA (the gDNA indicates where to cleave); two major and two minor products are seen which correspond to cleavage sites between nucleotides 9/10, 10/11, 13/14, and 14/15 downstream of the target residue base-paired with the 5'-end of the gDNA (PubMed:24442234, PubMed:27741323, PubMed:28319081, PubMed:28319084). Efficient guide-dependent tDNA cleavage requires a minimal length of 15 bp and is maximal at 19 bp (PubMed:28319081). Prefers gDNA with 5'-phosphorylated purines and 3'-pyrimidines; changing these bases alters the cleavage activity and patterns (PubMed:28319084). Also has guide-independent activity on tDNA called 'chopping' (PubMed:28319081). Probably a first round of guide-independent activity on an invading plasmid or virus would generate guide DNAs for subsequent, more efficient, guide-dependent degradation of invading nucleic acids (PubMed:28319081). Has no activity on substrate with a mismatch at positions 10 and 11, on ssDNA or RNA, nor on DNA:RNA hybrids (PubMed:24442234). Digests longer (750 bp) dsDNA as well as circular plasmid and naked genomic DNA, but not chromatin, in a guide DNA-independent manner (PubMed:28319081). Addition of endogenous histone A3 protects DNA from cleavage, while cleavage is insensitive to methylation (PubMed:28319081). When plasmid encoding active or mutated protein (Ala-541) is transformed into Sulfolobus acidocaldarius about 25-fold fewer transformants are found with active protein; reduced levels of plasmid are found in wild-type transformed cells. While S.acidocaldarius grows at a similar temperature to M.jannaschii (70 to 80 degrees Celsius) it has very different histone-like proteins, which presumably do not protect against MjAgo (PubMed:28319081). Binds ssDNA, dsDNA and DNA-RNA hybrids; binding is most efficient with dsDNA (PubMed:24442234).^{[1] [2] [3] [4] [5]}

See Also

• Argonaute 3D structures

References

1. ↑ Zander A, Holzmeister P, Klose D, Tinnefeld P, Grohmann D. Single-molecule FRET supports the two-state model of Argonaute action. RNA Biol. 2014;11(1):45-56. PMID:24442234 doi:10.4161/rna.27446
2. ↑ Willkomm S, Zander A, Grohmann D, Restle T. Mechanistic Insights into Archaeal and Human Argonaute Substrate Binding and Cleavage Properties. PLoS One. 2016 Oct 14;11(10):e0164695. PMID:27741323 doi:10.1371/journal.pone.0164695
3. ↑ Zander A, Willkomm S, Ofer S, van Wolferen M, Egert L, Buchmeier S, Stöckl S, Tinnefeld P, Schneider S, Klingl A, Albers SV, Werner F, Grohmann D. Guide-independent DNA cleavage by archaeal Argonaute from Methanocaldococcus jannaschii. Nat Microbiol. 2017 Mar 20;2:17034. PMID:28319081 doi:10.1038/nmicrobiol.2017.34
4. ↑ Willkomm S, Oellig CA, Zander A, Restle T, Keegan R, Grohmann D, Schneider S. Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein. Nat Microbiol. 2017 Mar 20;2:17035. doi: 10.1038/nmicrobiol.2017.35. PMID:28319084 doi:http://dx.doi.org/10.1038/nmicrobiol.2017.35
5. ↑ Zander A, Willkomm S, Ofer S, van Wolferen M, Egert L, Buchmeier S, Stöckl S, Tinnefeld P, Schneider S, Klingl A, Albers SV, Werner F, Grohmann D. Guide-independent DNA cleavage by archaeal Argonaute from Methanocaldococcus jannaschii. Nat Microbiol. 2017 Mar 20;2:17034. PMID:28319081 doi:10.1038/nmicrobiol.2017.34
6. ↑ Willkomm S, Oellig CA, Zander A, Restle T, Keegan R, Grohmann D, Schneider S. Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein. Nat Microbiol. 2017 Mar 20;2:17035. doi: 10.1038/nmicrobiol.2017.35. PMID:28319084 doi:http://dx.doi.org/10.1038/nmicrobiol.2017.35