Lamassu-Fam
Description
The original types of Lamassu systems are Lamassu Type 1 (N/A) and Type 2 (N/A) . They both necessarily comprise two genes lmuA and lmuB, to which a third gene (lmuC) is added in the case of Lamassu Type 2.
Lamassu has been suggested to be a large family of defense systems, that can be classified into multiple subtypes (N/A) .
These systems all encode the lmuB gene, and in most cases also comprise lmuC. In addition to these two core genes, Lamassu systems of various subtypes encode a third protein, hypothesized to be the Abi effector protein (N/A) . This effector can be proteins encoding endonuclease domains, SIR2-domains, or even hydrolase domains (N/A) . Systems of the extended Lamassu family can be found in 10% of prokaryotic genomes (N/A) .
Lamassu were also described as DdmABC in Vibrio cholerae (N/A, N/A) . They were found to be anti plasmids and thus to eliminate plasmids from the seventh pandemic Vibrio cholerae* (N/A) . The DdmABC system corresponds to a Lamassu-Fam Cap4 nuclease system.
Molecular mechanism
Lamassu systems function through abortive infection (Abi), but the molecular mechanism remains to be described. It was shown that, in Vibrio cholerae palindromic DNA sequences that are predicted to form stem-loop hairpin trigger the system (N/A) .
Example of genomic structure
The majority of the Lamassu-Fam systems are composed of 3 proteins: LmuA, LmuB and, an accessory LmuC proteins. LmuA is the effector and encode for different domains depending on the subsystem.
A total of 11 subsystems have been described for the Lamassu-Fam system.
Here are some examples found in the RefSeq database:
The Lamassu-Amidase system in Variovorax sp. PBL-H6 (GCF_901827155.1, NZ_LR594659) is composed of 2 proteins LmuA_effector_Amidase (WP_162575880.1) LmuB_SMC_Amidase (WP_162575881.1)
The Lamassu-Cap4_nuclease system in Opitutus terrae (GCF_000019965.1, NC_010571) is composed of 3 proteins LmuA_effector_Cap4_nuclease_II (WP_012377261.1) LmuC_acc_Lipase (WP_012377262.1) LmuB_SMC_Lipase (WP_012377263.1)
The Lamassu-FMO system in Mesorhizobium sp. B2-1-8 (GCF_006442545.2, NZ_CP083952) is composed of 3 proteins LmuA_effector_FMO (WP_181178269.1) LmuC_acc_FMO (WP_140755520.1) LmuB_SMC_FMO (WP_181178271.1)
The Lamassu-Hydrolase_Protease system in Deefgea piscis (GCF_013284055.1, NZ_CP054143) is composed of 4 proteins LmuA_effector_Hydrolase (WP_173533336.1) LmuA_effector_Protease (WP_173533337.1) LmuC_acc_hydrolase_protease (WP_173533338.1) LmuB_SMC_Hydrolase_protease (WP_173533339.1)
The Lamassu-Hypothetical system in Dehalococcoides mccartyi (GCF_002007905.1, NZ_CP019866) is composed of 3 proteins LmuA_effector_hypothetical (WP_077975422.1) LmuC_acc_hypothetical (WP_077975423.1) LmuB_SMC_hypothetical (WP_077975424.1)
The Lamassu-Lipase system in Klebsiella michiganensis (GCF_022869885.1, NZ_CP094999) is composed of 3 proteins LmuB_SMC_Lipase (WP_016157240.1) LmuC_acc_Lipase (WP_032931759.1) LmuA_effector_Lipase (WP_042945865.1)
The Lamassu-Mrr system in Agrobacterium tumefaciens (GCF_022760295.1, NZ_CP092895) is composed of 3 proteins LmuA_effector_Mrr (WP_223215665.1) LmuC_acc_Mrr (WP_220318798.1) LmuB_SMC_Mrr (WP_220318797.1)
The Lamassu-PDDEXK system in Corynebacterium pseudodiphtheriticum (GCF_023509295.1, NZ_CP091864) is composed of 3 proteins LmuC_acc_PDDEXK (WP_249620350.1) LmuB_SMC_PDDEXK (WP_249620351.1) LmuA_effector_PDDEXK (WP_249620352.1)
The Lamassu-Protease system in Enterococcus hirae (GCF_014218175.1, NZ_CP042289) is composed of 3 proteins LmuA_effector_Protease (WP_034866244.1) LmuC_acc_hydrolase_protease (WP_181916367.1) LmuB_SMC_Hydrolase_protease (WP_034866249.1)
The Lamassu-Sir2 system in Enterococcus faecalis (GCF_023375525.1, NZ_CP091235) is composed of 3 proteins LmuA_effector_Sir2 (WP_231436660.1) LmuC_acc_Sir2 (WP_231436659.1) LmuB_SMC_Sir2 (WP_231436658.1)