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Human mitochondrial alanyl‐tRNA synthetase: A variant mode of RNA recognition
Author(s) -
Borchert Karen,
Anderson David,
Natala Nakita,
Zhu Yirong,
Riley Lucas,
Ener Maraia,
Brown Julia,
Chihade Joseph
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1000.1
Subject(s) - aminoacylation , transfer rna , mitochondrion , biology , aminoacyl trna synthetase , rna , biochemistry , t arm , enzyme , genetics , gene
Metazoan mitochondria contain tRNAs which are highly diverged in both sequence and structure from those found elsewhere in evolution. These tRNAs are recognized and specifically charged by nuclearly encoded mitochondrial aminoacyl‐tRNA synthetases. Our work is focused on characterizing the interaction between human mitochondrial alanyl‐tRNA synthetase (Hs mt AlaRS) and its tRNA substrate. Mutational analysis of both the enzyme and tRNA substrate estabilished that contacts between the acceptor stem and the N‐terminal domains of the enzyme are relatively unimportant for establishing tRNA identity, in contrast to all previously characterized alanyl‐tRNA synthetases. However, the C‐terminal half of Hs mt AlaRS and the D‐acceptor domain of the tRNA are required for aminoacylation, suggesting that in the human mitochondrial system a second set of tRNA‐AlaRS contacts plays a role in determining tRNA Ala identity. Because mitochondrial tRNAs are structurally fragile, we have used in‐line probing to validate RNA secondary and tertiary structure. An important identity element in non‐mitochondrial tRNA Ala is a G3:U70 wobble pair. Comparing N‐terminal AlaRS sequences from a variety of mitochondrial and non‐mitochondrial sources, some of which aminoacylate substrates that lack this element, has allowed us to identify residues associated with acceptor stem recognition.