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Further insights into the tRNA modification process controlled by proteins MnmE and GidA of Escherichia coli.
Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology). (Björk)
2006 (English)In: Nucleic Acids Res, ISSN 1362-4962, Vol. 34, no 20, 5892-905 p.Article in journal (Refereed) Published
Abstract [en]

In Escherichia coli, proteins GidA and MnmE are involved in the addition of the carboxymethylaminomethyl (cmnm) group onto uridine 34 (U34) of tRNAs decoding two-family box triplets. However, their precise role in the modification reaction remains undetermined. Here, we show that GidA is an FAD-binding protein and that mutagenesis of the N-terminal dinucleotide-binding motif of GidA, impairs capability of this protein to bind FAD and modify tRNA, resulting in defective cell growth. Thus, GidA may catalyse an FAD-dependent reaction that is required for production of cmnmU34. We also show that GidA and MnmE have identical cell location and that both proteins physically interact. Gel filtration and native PAGE experiments indicate that GidA, like MnmE, dimerizes and that GidA and MnmE directly assemble in an alpha2beta2 heterotetrameric complex. Interestingly, high-performance liquid chromatography (HPLC) analysis shows that identical levels of the same undermodified form of U34 are present in tRNA hydrolysates from loss-of-function gidA and mnmE mutants. Moreover, these mutants exhibit similar phenotypic traits. Altogether, these results do not support previous proposals that activity of MnmE precedes that of GidA; rather, our data suggest that MnmE and GidA form a functional complex in which both proteins are interdependent.

Place, publisher, year, edition, pages
2006. Vol. 34, no 20, 5892-905 p.
Keyword [en]
Antibodies; Bacterial/biosynthesis/immunology, Bacterial Proteins/analysis/chemistry/*metabolism, Escherichia coli/genetics/metabolism, Escherichia coli Proteins/*metabolism, Flavin-Adenine Dinucleotide/metabolism, GTP Phosphohydrolases/*metabolism, Mutation, Phenotype, Protein Structure; Tertiary, RNA Processing; Post-Transcriptional, RNA; Transfer/chemistry/*metabolism, Uridine/*metabolism
URN: urn:nbn:se:umu:diva-16729PubMedID: 17062623OAI: diva2:156402
Available from: 2007-10-09 Created: 2007-10-09 Last updated: 2011-01-11Bibliographically approved

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