DNA-methyltransferase SsoII interaction with own promoter region binding site

Abstract

The investigation of Sso II DNA-methyltransferase (M.Sso II) interaction with the intergenic region of Sso II restriction-modification system was carried out. Seven guanine residues protected by M. Sso II from methylation with dimethylsulfate and thus probably involved in enzyme-DNA recognition were identified. Six of them are located symmetrically within the 15 bp inverted repeat inside the Sso II promoter region. The crosslinking of Sso II methyltransferase with DNA duplexes containing 5-bromo-2'-deoxyuridine (br5dU) instead of thymidine was performed. The crosslinked products were obtained in all cases, thus proving that tested thymines were in proximity with enzyme. The ability to produce the crosslinked products in one case was 2-5-fold higher than in other ones. This allowed us to imply that thymine residue in this position of the inverted repeat could be in contact with M. Sso II. Based on the experimental data, two symmetrical 4 bp clusters (GGAC), which could be involved in the interaction with M. Sso II in the DNA-protein complex, were identified. The model of M. Sso II interaction with its own promoter region was proposed.

Thymidine Glycol: The Effect on DNA Structure and DNA Binding by Site-Specific Proteins

“…However, the protein dimer can assemble the proper complex only when the DNA is long enough (60 bp and more) [39]. The 31-bp duplexes used in the present work allow to detect only the intermediate complex where one M.SsoII molecule binds to one DNA duplex -either to the "left" half or to the "right" half of the regulatory site [34] [70] [71]. These two complexes have equal molecular mass and therefore cannot be distinguished by EMSA.…”

Diverse Domains of (Cytosine-5)-DNA Methyltransferases: Structural and Functional Characterization

“…Moreover, M.SsoII interacts with the intergenic region of the SsoII R-M system protecting from DNase I hydrolysis 48 nucleotides in the top strand and 52 nucleotides in the bottom strand [75]. The intergenic region contains a 15 bp inverted repeat (regulatory site) [76]. Seven guanine bases interacting with M.SsoII are identified using protection footprinting; six of them are located inside the regulatory site symmetrically relative to the central А•Т pair ( Figure 7) [76].…”

“…The intergenic region contains a 15 bp inverted repeat (regulatory site) [76]. Seven guanine bases interacting with M.SsoII are identified using protection footprinting; six of them are located inside the regulatory site symmetrically relative to the central А•Т pair ( Figure 7) [76]. Interference footprinting experiments with formic acid, hydrazine, dimethyl sulfate, and N-ethyl-N-nitrosourea show 6 guanine, 2 adenine, and 4 thymine residues as well as 6 phosphate groups interacting with M.SsoII.…”

Maintenance Forced by a Restriction-Modification System Can Be Modulated by a Region in Its Modification Enzyme Not Essential for Methyltransferase Activity

“…Furthermore, type II RM systems show some similarity to viruses in their requirements for regulation of gene expression (30,49,60,62,66) in that, when they enter a new host, they have to establish themselves without excessive killing of the host cells. After establishment, type II RM systems, like the other types of postsegregational systems, are expected to tightly regulate their gene expression.…”