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-Structure paper
タイトル | Phage T3 overcomes the BREX defense through SAM cleavage and inhibition of SAM synthesis by SAM lyase. |
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ジャーナル・号・ページ | Cell Rep, Vol. 42, Issue 8, Page 112972, Year 2023 |
掲載日 | 2023年8月13日 |
著者 | Aleksandr Andriianov / Silvia Trigüis / Alena Drobiazko / Nicolas Sierro / Nikolai V Ivanov / Maria Selmer / Konstantin Severinov / Artem Isaev / |
PubMed 要旨 | Bacteriophage T3 encodes a SAMase that, through cleavage of S-adenosyl methionine (SAM), circumvents the SAM-dependent type I restriction-modification (R-M) defense. We show that SAMase also allows ...Bacteriophage T3 encodes a SAMase that, through cleavage of S-adenosyl methionine (SAM), circumvents the SAM-dependent type I restriction-modification (R-M) defense. We show that SAMase also allows T3 to evade the BREX defense. Although SAM depletion weakly affects BREX methylation, it completely inhibits the defensive function of BREX, suggesting that SAM could be a co-factor for BREX-mediated exclusion of phage DNA, similar to its anti-defense role in type I R-M. The anti-BREX activity of T3 SAMase is mediated not just by enzymatic degradation of SAM but also by direct inhibition of MetK, the host SAM synthase. We present a 2.8 Å cryoelectron microscopy (cryo-EM) structure of the eight-subunit T3 SAMase-MetK complex. Structure-guided mutagenesis reveals that this interaction stabilizes T3 SAMase in vivo, further stimulating its anti-BREX activity. This work provides insights in the versatility of bacteriophage counterdefense mechanisms and highlights the role of SAM as a co-factor of diverse bacterial immunity systems. |
リンク | Cell Rep / PubMed:37578860 |
手法 | EM (単粒子) |
解像度 | 2.8 - 3.0 Å |
構造データ | EMDB-15952: Map from local refinement with a mask around T3 SAM lyase from the complex of T3 SAM lyase with MetK. EMDB-15953, PDB-8bb1: |
化合物 | ChemComp-CL: ChemComp-HOH: |
由来 |
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キーワード | LYASE / SAM lyase / complex |