2007
DOI: 10.1074/jbc.m700926200
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Two Alternative Conformations of S-Adenosyl-L-homocysteine Bound to Escherichia coli DNA Adenine Methyltransferase and the Implication of Conformational Changes in Regulating the Catalytic Cycle

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Cited by 14 publications
(14 citation statements)
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“…The results obtained here with wild‐type EcoDam closely match previous data with respect to absolute rates and specificity 14. 17 The rate of methylation of GATC substrates by the wild‐type enzyme corresponded to 0.8 turnovers min −1 . The enzyme was highly specific and substrates modified at Gua1 were methylated with at least 80‐fold reduced rates.…”
Section: Resultssupporting
confidence: 88%
See 1 more Smart Citation
“…The results obtained here with wild‐type EcoDam closely match previous data with respect to absolute rates and specificity 14. 17 The rate of methylation of GATC substrates by the wild‐type enzyme corresponded to 0.8 turnovers min −1 . The enzyme was highly specific and substrates modified at Gua1 were methylated with at least 80‐fold reduced rates.…”
Section: Resultssupporting
confidence: 88%
“…It is striking that all variants containing the Y138R exchange displayed an increase in activity as compared to the wild‐type enzyme. We have previously shown that in EcoDam, formation of the Gua1 interaction is a late step in the conformational rearrangement that occurs during target sequence interaction and requires the ordering of the N‐terminal loop of EcoDam 17. In contrast to K9, R138 is located at the base of the β‐hairpin and it can interact with Gua1 without the requirement for conformational change; this might explain the increase in activity in all variants containing R138.…”
Section: Discussionmentioning
confidence: 99%
“…It supports the notion that Lys 11 contacts the N 7 of Gua1, because such contact cannot contribute to the discrimination of gua-nine and adenine. In extrapolation these results suggest a comparable role of the N-terminal loop in M.EcoRV and EcoDam, which explains the finding that cofactor binding influences DNA recognition by M.EcoRV (19), because we have recently shown that slight structural rearrangements of this loop in EcoDam couple coenzyme binding, recognition of the first base pair and insertion of the flipped target base into the base binding pocket of the enzyme (27).…”
Section: Resultssupporting
confidence: 52%
“…SAM usually adopts an extended conformation in the known SAM-dependent MTases structures although a folded catalytically irrelevant conformation of SAM was also observed in the human Dim1 rRNA MTase (PDB code 1ZQ9) (52). The existence of alternative conformations of SAH has previously been reported in DNA adenine MTases EcoDam (53), M. RsrI (54) and M. TaqI (55). The extended conformation, in which the methyl group of SAM points toward the atom to be methylated, is compatible with catalysis.…”
Section: Discussionmentioning
confidence: 70%