Sci Rep 2016 Feb 18;6:21438. doi: 10.1038/srep21438.
Fleming IM1, Paris Z1, Gaston KW2, Balakrishnan R1,2, Fredrick K1,3, Rubio MA1, Alfonzo JD1,3.
Abstract
Most
eukaryotic ribosomes contain 26/28S, 5S, and 5.8S large subunit
ribosomal RNAs (LSU rRNAs) in addition to the 18S rRNA of the small
subunit (SSU rRNA). However, in kinetoplastids, a group of organisms
that include medically important members of the genus Trypanosoma and
Leishmania, the 26/28S large subunit ribosomal RNA is uniquely composed
of 6 rRNA fragments. In addition, recent studies have shown the presence
of expansion segments in the large ribosomal subunit (60S) of
Trypanosoma brucei. Given these differences in structure, processing and
assembly, T. brucei ribosomes may require biogenesis factors not found
in other organisms. Here, we show that one of two putative
3-methylcytidine methyltransferases, TbMTase37 (a homolog of human
methyltransferase-like 6, METTL6), is important for ribosome stability
in T. brucei. TbMTase37 localizes to the nucleolus and depletion of the
protein results in accumulation of ribosomal particles lacking srRNA 4
and reduced levels of polysome associated ribosomes. We also find that
TbMTase37 plays a role in cytokinesis, as loss of the protein leads to
multi-flagellated and multi-nucleated cells.
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