Restriction modification N6-adenine DNA methyltransferase TRD-CR, similar to RMtype1 Calditerrivibrio nitroreducens M.Cni19672ORF1405P TRD1-CR1 and RMtype11G Helicobacter cinaedi PAGU611 RM.Hci611ORFHP TRD1-CR1
The recognition sequence of Calditerrivibrio nitroreducens M.Cni19672ORF1405P is undetermined, and the predicted recognition sequence of RM.Hci611ORFHP is 5'... GAGNNNNNGT ... 3'. M.Cni19672ORF1405P is a putative type I N6-adenine DNA methyltransferase. RM.Hci611ORFHP is a type II subtype gamma (also called type IIG and type IIC) N6-adenine DNA methyltransferase. Both are DNA methyltransferase-specificity subunit fusion proteins, they each have a domain corresponding to a HsdM methylation (M) subunit followed by a C-terminal, TRD-CR-like domain for sequence-recognition, which corresponds to the HsdS specificty (S) subunit. The latter consists of two variable TRDs, and two CRs which separate the TRDs; the TRDs each bind to different specific sequences in the DNA. RM.Hci611ORFHP has an additional N-terminal HSDR_N domain. Restriction-modification (RM) systems protect a bacterial cell against invasion of foreign DNA by endonucleolytic cleavage of DNA that lacks a site specific modification. The host genome is protected from cleavage by methylation of specific nucleotides in the target sites. In type I systems, both restriction and modification activities are present in one heteromeric enzyme complex composed of one DNA specificity (S) subunit, two modification (M) subunits, and two restriction (R) subunits.
Comment:based on related TRD1-CR1/TRD2-CR2 's with structure
Comment:HsdS DNA specificity subunit, and HsdM DNA modification subunit; type I RM enzymes, are formed from a core methyltransferase (MTase) comprised of one HsdS subunit and two HsdM subunits, this is complexed with two HsdR DNA restriction subunits (R2M2S1)
Comment:CR1 and CR2 refer to two coiled-coiled structures, found at the ends of the primary sequence of S-subunit TRD1 and TRD2 respectively; CR1 and CR2 run antiparallel to each other and interact by hydrophobic contacts between a series of hydrophobic residues
Jiyao W et al.(2023). "The conserved domain database in 2023.",