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Title | Structural insights into assembly, operation and inhibition of a type I restriction-modification system. |
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Journal, issue, pages | Nat Microbiol, Vol. 5, Issue 9, Page 1107-1118, Year 2020 |
Publish date | Jun 1, 2020 |
Authors | Yina Gao / Duanfang Cao / Jingpeng Zhu / Han Feng / Xiu Luo / Songqing Liu / Xiao-Xue Yan / Xinzheng Zhang / Pu Gao / |
PubMed Abstract | Type I restriction-modification (R-M) systems are widespread in prokaryotic genomes and provide robust protection against foreign DNA. They are multisubunit enzymes with methyltransferase, ...Type I restriction-modification (R-M) systems are widespread in prokaryotic genomes and provide robust protection against foreign DNA. They are multisubunit enzymes with methyltransferase, endonuclease and translocase activities. Despite extensive studies over the past five decades, little is known about the molecular mechanisms of these sophisticated machines. Here, we report the cryo-electron microscopy structures of the representative EcoR124I R-M system in different assemblies (RMS, RMS and MS) bound to target DNA and the phage and mobile genetic element-encoded anti-restriction proteins Ocr and ArdA. EcoR124I can precisely regulate different enzymatic activities by adopting distinct conformations. The marked conformational transitions of EcoR124I are dependent on the intrinsic flexibility at both the individual-subunit and assembled-complex levels. Moreover, Ocr and ArdA use a DNA-mimicry strategy to inhibit multiple activities, but do not block the conformational transitions of the complexes. These structural findings, complemented by mutational studies of key intermolecular contacts, provide insights into assembly, operation and inhibition mechanisms of type I R-M systems. |
External links | Nat Microbiol / PubMed:32483229 |
Methods | EM (single particle) |
Resolution | 3.97 - 7.38 Å |
Structure data | EMDB-30166, PDB-7bst: EMDB-30180, PDB-7bto: EMDB-30181, PDB-7btp: EMDB-30182, PDB-7btq: EMDB-30183, PDB-7btr: EMDB-30184: EMDB-30185: EMDB-30186: EMDB-30187: EMDB-30188: |
Source |
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Keywords | IMMUNE SYSTEM / Cryoelectron microscopy / Innate immune mechanism / Complex |