Protein
Type-1 restriction enzyme MjaXIP specificity protein
Organism
Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440)
Function
The M and S subunits together form a methyltransferase (MTase) that methylates two adenine residues in complementary strands of a bipartite DNA recognition sequence. In the presence of the R subunit the complex can also act as an endonuclease, binding to the same target sequence but cutting the DNA some distance from this site. Whether the DNA is cut or modified depends on the methylation state of the target sequence. When the target site is unmodified, the DNA is cut. When the target site is hemimethylated, the complex acts as a maintenance MTase modifying the DNA so that both strands become methylated. Subunit S dictates DNA sequences specificity (By similarity).
Similarity
Belongs to the type-I restriction system S methylase family.
Sequence
MFYKEENFKKTEIGEIPEDWEIVELKDVCKKIKAGGTPKTSVEEYYKNGTIPFVKIEDITNSNKYLTNTKIKITEEGLNNSNAWIVPKNSVLFAMYGSIGETAINKIEVATNQAILGIIPKDNILESEFLYYILAKNKNYYSKLGMQTTQKNLNAQIVKSFKIPLPPLEEQKQIAKILTKIDEGIEIIEKSINKLERIKKGLMHKLLTKGIGHSRFKKSEIGEIPEDWEVFEIKDIFEVKTGTTPSTKKSEYWENGEINWITPLDLSRLNEKIYIGSSERKVTKIALEKCNLNLIPKGSIIISTRAPVGYVAVLTVESTFNQGCKGLFQKNNDSVNTEFYAYYLKFKKNLLENLSGGSTFKELSKSMLENFKIPLPPLEEQKQIAKILSSVDKSIELKKQKKEKLQRMKKKIMELLLTGKVRVKT