NAD(+) hydrolase ThsA

UniProtKB accession:  J8G6Z1

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UniProtKB description:  NAD(+) hydrolyzing component (NADase) of the Thoeris antiviral defense system, composed of ThsA and ThsB. Activated by a signal molecule generated by endogenous ThsB (AC J8G8J6) or ThsB' (AC J8CSK2, probably 3'cADPR), by TIR1 and TIR2 from B.dafuensis or by BdTIR from B.distachyon (AC I1GTC2, probably 2'cADPR). Upon activation binds and hydrolyzes NAD(+), leading to cell death and inhibition of phage replication. Not seen to bind DNA (PubMed:32499527, PubMed:34853457, PubMed:36174646). Activation is 50-100x more sensitive to 3' cyclic ADP-D-ribose (3'cADPR) than 2'cADPR (PubMed:36174646). In another paper ThsA is not activated by any tested cADPR isomer, although it binds 3'cADPR; it was suggested the protein is already in a fully active state (PubMed:36048923). Expression of ThsA and ThsB in B.subtilis (strain BEST7003) confers resistance to phages phi29, SBSphiC, SBSphiJ and SPO1 (PubMed:29371424, PubMed:34853457). At multiplicity of infection (MOI) of 0.05 Thoeris-encoding cultures grow normally when infected with SPO1, at MOI 5 cultures collapse prematurely by 90 minutes post-infection, thus the phage are not able to complete a replication cycle. NAD(+) levels fall and ADP-D-ribose levels rise 60 minutes post-infection. Thoeris cultures eventually recover, but retain the same susceptibility to SPO1 (PubMed:34853457).