3TPZ

2.1 Angstrom crystal structure of the L114P mutant of E. Coli KsgA

Summary for 3TPZ

• Entry DOI: 10.2210/pdb3tpz/pdb
• Related: 1QAM 1QYR 2FYC 3FTD 3FUT 3FYD
• Descriptor: Ribosomal RNA small subunit methyltransferase A, CHLORIDE ION, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: rrna adenine dimethyltransferase, ribogenesis, transferase
• Biological source: Escherichia coli
• Cellular location: Cytoplasm (Potential): P06992
• Total number of polymer chains: 2
• Total formula weight: 61037.97

Authors

Scarsdale, J.N.,Musayev, F.N.,Rife, J.P. (deposition date: 2011-09-08, release date: 2012-02-15, Last modification date: 2023-09-13)

Primary citation

O'Farrell, H.C.,Musayev, F.N.,Scarsdale, J.N.,Rife, J.P.
Control of Substrate Specificity by a Single Active Site Residue of the KsgA Methyltransferase.
Biochemistry, 51:466-474, 2012

PubMed Abstract: The KsgA methyltransferase is universally conserved and plays a key role in regulating ribosome biogenesis. KsgA has a complex reaction mechanism, transferring a total of four methyl groups onto two separate adenosine residues, A1518 and A1519, in the small subunit rRNA. This means that the active site pocket must accept both adenosine and N(6)-methyladenosine as substrates to catalyze formation of the final product N(6),N(6)-dimethyladenosine. KsgA is related to DNA adenosine methyltransferases, which transfer only a single methyl group to their target adenosine residue. We demonstrate that part of the discrimination between mono- and dimethyltransferase activity lies in a single residue in the active site, L114; this residue is part of a conserved motif, known as motif IV, which is common to a large group of S-adenosyl-L-methionine-dependent methyltransferases. Mutation of the leucine to a proline mimics the sequence found in DNA methyltransferases. The L114P mutant of KsgA shows diminished overall activity, and its ability to methylate the N(6)-methyladenosine intermediate to produce N(6),N(6)-dimethyladenosine is impaired; this is in contrast to a second active site mutation, N113A, which diminishes activity to a level comparable to L114P without affecting the methylation of N(6)-methyladenosine. We discuss the implications of this work for understanding the mechanism of KsgA's multiple catalytic steps.

PubMed: 22142337
DOI: 10.1021/bi201539j

Experimental method

X-RAY DIFFRACTION (2.1 Å)