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2'-O-ribose methylation of cap2 in human: function and evolution in a horizontally mobile family.

Werner M, Purta E, Kaminska KH, Cymerman IA, Campbell DA, Mittra B, Zamudio JR, Sturm NR, Jaworski J, Bujnicki JM - Nucleic Acids Res. (2011)

Bottom Line: The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1.The 2'-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes.With the capping enzymes in hand their biological purpose can be ascertained.

View Article: PubMed Central - PubMed

Affiliation: International Institute of Molecular and Cell Biology in Warsaw, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland.

ABSTRACT
The 5' cap of human messenger RNA consists of an inverted 7-methylguanosine linked to the first transcribed nucleotide by a unique 5'-5' triphosphate bond followed by 2'-O-ribose methylation of the first and often the second transcribed nucleotides, likely serving to modify efficiency of transcript processing, translation and stability. We report the validation of a human enzyme that methylates the ribose of the second transcribed nucleotide encoded by FTSJD1, henceforth renamed HMTR2 to reflect function. Purified recombinant hMTr2 protein transfers a methyl group from S-adenosylmethionine to the 2'-O-ribose of the second nucleotide of messenger RNA and small nuclear RNA. Neither N(7) methylation of the guanosine cap nor 2'-O-ribose methylation of the first transcribed nucleotide are required for hMTr2, but the presence of cap1 methylation increases hMTr2 activity. The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1. The details of how and why specific transcripts undergo modification with these ribose methylations remains to be elucidated. The 2'-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes. With the capping enzymes in hand their biological purpose can be ascertained.

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Domain architecture of hMTr1 and hMTr2 proteins. Domain boundaries were predicted according to protein fold recognition analyses carried out via the GeneSilico metaserver (38). Amino acid residues important for the MTase activity are indicated.
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Figure 1: Domain architecture of hMTr1 and hMTr2 proteins. Domain boundaries were predicted according to protein fold recognition analyses carried out via the GeneSilico metaserver (38). Amino acid residues important for the MTase activity are indicated.

Mentions: Structure prediction in combination with multiple sequence alignment analysis (data not shown) confirmed that FTSJD2, the putative hMTr1, carried a putative nuclear localization signal (NLS), a G-patch domain potentially involved in RNA binding, an RFM domain with a conserved K-D-K triad characteristic for 2′-O-ribose MTases, a GTase-like domain lacking catalytic residues (26,42) and a WW domain potentially involved in protein–protein interactions. FTSJD1, the candidate hMTr2, was composed of two RFM domains (Figure 1). A multiple sequence alignment of hMTr2 orthologs (Supplementary Figure S3) revealed that the N-terminal RFM domain had a conserved SAM-binding site (motifs I–III). Interestingly, in motif I the Asp residue present in other 2′-O-ribose MTases was replaced by His, but it reappeared elsewhere, shifted three positions toward the C-terminus. As in hMTr1, the N-terminal RFM domain of hMTr2 contained a characteristic catalytic K-D-K triad. These residues were conserved in all members of this family, with the exception of proteins from Plasmodium, where they were replaced by the variant Y-(N/D)-K. Members of Plasmodium also exhibited deletions of one residue in motif I, and lost the otherwise universally conserved E residue in motif VIII, whose counterpart in RrmJ (E199) plays a minor role in the MTase activity (43). The C-terminal RFM domain was present in all members of the hMTr2 family, with the exception of two viral and one algal proteins, and was more variable than the N-terminal domain. Despite the overall homology to enzymatically active RFM domains, this domain lacked conserved residues required to bind SAM as motifs I–III were practically undetectable, and neither the K-D-K triad nor any other obvious candidates for an active site were identified.Figure 1.


2'-O-ribose methylation of cap2 in human: function and evolution in a horizontally mobile family.

Werner M, Purta E, Kaminska KH, Cymerman IA, Campbell DA, Mittra B, Zamudio JR, Sturm NR, Jaworski J, Bujnicki JM - Nucleic Acids Res. (2011)

Domain architecture of hMTr1 and hMTr2 proteins. Domain boundaries were predicted according to protein fold recognition analyses carried out via the GeneSilico metaserver (38). Amino acid residues important for the MTase activity are indicated.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3113572&req=5

Figure 1: Domain architecture of hMTr1 and hMTr2 proteins. Domain boundaries were predicted according to protein fold recognition analyses carried out via the GeneSilico metaserver (38). Amino acid residues important for the MTase activity are indicated.
Mentions: Structure prediction in combination with multiple sequence alignment analysis (data not shown) confirmed that FTSJD2, the putative hMTr1, carried a putative nuclear localization signal (NLS), a G-patch domain potentially involved in RNA binding, an RFM domain with a conserved K-D-K triad characteristic for 2′-O-ribose MTases, a GTase-like domain lacking catalytic residues (26,42) and a WW domain potentially involved in protein–protein interactions. FTSJD1, the candidate hMTr2, was composed of two RFM domains (Figure 1). A multiple sequence alignment of hMTr2 orthologs (Supplementary Figure S3) revealed that the N-terminal RFM domain had a conserved SAM-binding site (motifs I–III). Interestingly, in motif I the Asp residue present in other 2′-O-ribose MTases was replaced by His, but it reappeared elsewhere, shifted three positions toward the C-terminus. As in hMTr1, the N-terminal RFM domain of hMTr2 contained a characteristic catalytic K-D-K triad. These residues were conserved in all members of this family, with the exception of proteins from Plasmodium, where they were replaced by the variant Y-(N/D)-K. Members of Plasmodium also exhibited deletions of one residue in motif I, and lost the otherwise universally conserved E residue in motif VIII, whose counterpart in RrmJ (E199) plays a minor role in the MTase activity (43). The C-terminal RFM domain was present in all members of the hMTr2 family, with the exception of two viral and one algal proteins, and was more variable than the N-terminal domain. Despite the overall homology to enzymatically active RFM domains, this domain lacked conserved residues required to bind SAM as motifs I–III were practically undetectable, and neither the K-D-K triad nor any other obvious candidates for an active site were identified.Figure 1.

Bottom Line: The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1.The 2'-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes.With the capping enzymes in hand their biological purpose can be ascertained.

View Article: PubMed Central - PubMed

Affiliation: International Institute of Molecular and Cell Biology in Warsaw, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland.

ABSTRACT
The 5' cap of human messenger RNA consists of an inverted 7-methylguanosine linked to the first transcribed nucleotide by a unique 5'-5' triphosphate bond followed by 2'-O-ribose methylation of the first and often the second transcribed nucleotides, likely serving to modify efficiency of transcript processing, translation and stability. We report the validation of a human enzyme that methylates the ribose of the second transcribed nucleotide encoded by FTSJD1, henceforth renamed HMTR2 to reflect function. Purified recombinant hMTr2 protein transfers a methyl group from S-adenosylmethionine to the 2'-O-ribose of the second nucleotide of messenger RNA and small nuclear RNA. Neither N(7) methylation of the guanosine cap nor 2'-O-ribose methylation of the first transcribed nucleotide are required for hMTr2, but the presence of cap1 methylation increases hMTr2 activity. The hMTr2 protein is distributed throughout the nucleus and cytosol, in contrast to the nuclear hMTr1. The details of how and why specific transcripts undergo modification with these ribose methylations remains to be elucidated. The 2'-O-ribose RNA cap methyltransferases are present in varying combinations in most eukaryotic and many viral genomes. With the capping enzymes in hand their biological purpose can be ascertained.

Show MeSH