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Assembly stoichiometry of bacterial selenocysteine synthase and SelC (tRNA sec )
Author(s) -
Manzine Livia Regina,
Serrão Vitor Hugo Balasco,
Lima Luis Maurício Trambaioli da Rocha e,
de Souza Marcos Michel,
Bettini Jefferson,
Portugal Rodrigo Villares,
van Heel Marin,
Thiemann Otavio Henrique
Publication year - 2013
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2013.02.014
Subject(s) - transfer rna , selenocysteine , chemistry , crystallography , stoichiometry , supramolecular chemistry , stereochemistry , biochemistry , enzyme , rna , crystal structure , organic chemistry , cysteine , gene
In bacteria selenocysteyl–tRNA sec (SelC) is synthesized by selenocysteine synthase (SelA). Here we show by fluorescence anisotropy binding assays and electron microscopical symmetry analysis that the SelA–tRNA sec binding stoichiometry is of one tRNA sec molecule per SelA monomer (1:1) rather than the 1:2 value proposed previously. Negative stain transmission electron microscopy revealed a D5 pointgroup symmetry for the SelA–tRNA sec assembly both with and without tRNA sec bound. Furthermore, SelA can associate forming a supramolecular complex of stacked decamer rings, which does not occur in the presence of tRNA sec . We discuss the structure–function relationships of these assemblies and their regulatory role in bacterial selenocysteyl–tRNA sec synthesis.