9ard

Structural highlights

Function

PYCC1_ECOLX Pycsar (pyrimidine cyclase system for antiphage resistance) provides immunity against bacteriophage. The pyrimidine cyclase (PycC) synthesizes cyclic nucleotides in response to infection; these serve as specific second messenger signals. The signal activates the adjacent effector, leading to bacterial cell death and abortive phage infection. A clade E Pycsar system.^[1] The pyrimidine cyclase gene of a two-gene Pycsar system, generates cyclic CMP (cCMP) from CTP in response to bacteriophage infection. Has little to no activity on ATP, GTP or UTP. Expression of this and adjacent effector EcPycTM (AC P0DV25) confers resistance to bacteriophage P1 and T5; expression of this gene alone does not confer resistance. When cells expressing the Pycsar system are infected by phage T5 at low multiplicity of infection (0.2 MOI) the culture survives, at 2.0 MOI bacteria enter growth arrest. The same cells enter growth arrest after exposure to 250 uM cCMP but not cUMP; thus the effector protein responds only to the cNMP produced by its cognate NTP cyclase. Some of the cells treated with cCMP have abnormal membrane protrusions.^[2]

References

1. ↑ Tal N, Morehouse BR, Millman A, Stokar-Avihail A, Avraham C, Fedorenko T, Yirmiya E, Herbst E, Brandis A, Mehlman T, Oppenheimer-Shaanan Y, Keszei AFA, Shao S, Amitai G, Kranzusch PJ, Sorek R. Cyclic CMP and cyclic UMP mediate bacterial immunity against phages. Cell. 2021 Oct 7. pii: S0092-8674(21)01114-4. doi: 10.1016/j.cell.2021.09.031. PMID:34644530 doi:http://dx.doi.org/10.1016/j.cell.2021.09.031
2. ↑ Tal N, Morehouse BR, Millman A, Stokar-Avihail A, Avraham C, Fedorenko T, Yirmiya E, Herbst E, Brandis A, Mehlman T, Oppenheimer-Shaanan Y, Keszei AFA, Shao S, Amitai G, Kranzusch PJ, Sorek R. Cyclic CMP and cyclic UMP mediate bacterial immunity against phages. Cell. 2021 Oct 7. pii: S0092-8674(21)01114-4. doi: 10.1016/j.cell.2021.09.031. PMID:34644530 doi:http://dx.doi.org/10.1016/j.cell.2021.09.031