Partial methylation of two adjacent adenosines in ribosomes fromEuglena gracilischloroplasts suggests evolutionary loss of an intermediate stage in the methyl-transfer reaction | Zendy

C.P.J.J. van Buul | Zendy; M.A. Hamersma | Zendy; Wouter F. Visser | Zendy; P.H. Van Knippenberg | Zendy

Open Access

Partial methylation of two adjacent adenosines in ribosomes fromEuglena gracilischloroplasts suggests evolutionary loss of an intermediate stage in the methyl-transfer reaction

Author(s) -

C.P.J.J. van Buul,

M.A. Hamersma,

Wouter F. Visser,

P.H. Van Knippenberg

Publication year - 1984

Publication title -

nucleic acids research

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 9.008

H-Index - 537

eISSN - 1362-4954

pISSN - 0305-1048

DOI - 10.1093/nar/12.23.9205

Subject(s) - biology , euglena gracilis , methylation , ribosome , chloroplast , ribosomal rna , transfer rna , rna , mutant , biochemistry , microbiology and biotechnology , genetics , dna , gene

Bacterial, cytoplasmic and organellar ribosomes from a wide phylogenetic spectrum of organisms have a characteristic m6(2)Am6(2)A structure near the 3' end of the RNA of the small ribosomal subunit (SSU). We have studied one of the few exceptions to this extremely conserved post-transcriptionally modified sequence, i.e. dimethylation of only one of the two A's in chloroplasts from Euglena gracilis. It was established that only the A closest to the 5' end is dimethylated, the other one being unmodified. The methylation reaction was studied in vitro using ribosomes from a kasugamycin resistant mutant (ksgA) of Escherichia coli and purified methyl-transferase. Using limited amounts of the methyl donor S-adenosylmethionine (SAM) a partial level of methylation (50% of control) was attained. It is shown that in this case the 3' proximal A is dimethylated while the other is not. This suggests that dimethylation takes place in two successive stages. Apparently in E. gracilis chloroplasts the first stage of methylation does not occur.

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