Nucleic Acids Research Advance Access originally published online on October 5, 2006
Nucleic Acids Research 2006 34(19):5594-5602; doi:10.1093/nar/gkl573
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Nucleic Acids Research, 2006, Vol. 34, No. 19 5594-5602
© 2006 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Functional characterization of a 48 kDa Trypanosoma brucei cap 2 RNA methyltransferase
Department of Biological Sciences, State University of New York at Buffalo Buffalo, NY 14260, USA
*To whom the correspondence should be addressed. Tel: +1 716 645 2363; Fax: +1 716 645 2975; Email: kiongho{at}buffalo.edu
Received June 14, 2006. Revised July 20, 2006. Accepted July 20, 2006.
Kinetoplastid mRNAs possess a unique hypermethylated cap 4 structure derived from the standard m7GpppN cap structure, with 2'-O methylations on the first four ribose sugars and additional base methylations on the first adenine and the fourth uracil. While the enzymes responsible for m7GpppN cap 0 formations has been characterized in Trypanosoma brucei, the mechanism of cap 4 methylation and the role of the hypermethylated structure remain unclear. Here, we describe the characterization of a 48 kDa T.brucei 2'-O nucleoside methyltransferase (TbCom1). Recombinant TbCom1 transfers the methyl group from S-adenosylmethionine (AdoMet) to the 2'-OH of the second nucleoside of m7GpppNpNp-RNA to form m7GpppNpNmp-RNA. TbCom1 is also capable of converting cap 1 RNA to cap 2 RNA. The methyl transfer reaction is dependent on the m7GpppN cap, as the enzyme does not form a stable interaction with GpppN-terminated RNA. Mutational analysis establishes that the TbCom1 and vaccinia virus VP39 methyltransferases share mechanistic similarities in AdoMet- and cap-recognition. Two aromatic residues, Tyr18 and Tyr187, may participate in base-stacking interactions with the guanine ring of the cap, as the removal of each of these aromatic side-chains abolishes cap-specific RNA-binding.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  B. Mittra, J. R. Zamudio, J. M. Bujnicki, J. Stepinski, E. Darzynkiewicz, D. A. Campbell, and N. R. Sturm The TbMTr1 Spliced Leader RNA Cap 1 2 '-O-Ribose Methyltransferase from Trypanosoma brucei Acts with Substrate Specificity J. Biol. Chem., February 8, 2008; 283(6): 3161 - 3172. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. R. Zamudio, B. Mittra, S. Foldynova-Trantirkova, G. M. Zeiner, J. Lukes, J. M. Bujnicki, N. R. Sturm, and D. A. Campbell The 2'-O-Ribose Methyltransferase for Cap 1 of Spliced Leader RNA and U1 Small Nuclear RNA in Trypanosoma brucei Mol. Cell. Biol., September 1, 2007; 27(17): 6084 - 6092. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Takagi, S. Sindkar, D. Ekonomidis, M. P. Hall, and C. K. Ho Trypanosoma brucei Encodes a Bifunctional Capping Enzyme Essential for Cap 4 Formation on the Spliced Leader RNA J. Biol. Chem., June 1, 2007; 282(22): 15995 - 16005. [Abstract] [Full Text] [PDF]
|
|