Structural organization of the multienzyme complex of mammalian aminoacyl-tRNA synthetases

Godar, Dianne E.; Garcia, V.; Jacobo, A.; Aebi, Ueli; Yang, David C.H.

doi:10.1021/bi00418a038

Cited by 35 publications

(13 citation statements)

References 42 publications

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“…The critical role of LysRS for the assembly and stability of the MSC underscores the importance of maintaining a basal level of LysRS within the MSC, even when it is specifically released in response to external or internal stimulations. Indeed, some variance in the stoichiometry of binding of LysRS to the MSC has been reported (43,45,49).…”

Section: Discussionmentioning

confidence: 99%

Structural context for mobilization of a human tRNA synthetase from its cytoplasmic complex

Fang

Zhang

Shapiro

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Human lysyl-tRNA synthetase is bound to the multi-tRNA synthetase complex (MSC) that maintains and regulates the aminoacylation and nuclear functions of LysRS. The p38 scaffold protein binds LysRS to the MSC and, only with the appropriate cue, mobilizes LysRS for redirection to the nucleus to interact with the microphthalmia associated transcription factor (MITF). In recent work, an ðα 2 Þ 2 LysRS tetramer crystallized to yield a high-resolution structure and raised the question of how LysRS is arranged (dimer or tetramer) in the MSC to interact with p38. To understand the structural organization of the LysRS-p38 complex that regulates LysRS mobilization, we investigated the complex by use of small angle X-ray scattering and hydrogen-deuterium exchange with mass spectrometry in solution. The structure revealed a surprising α 2 β 1 ∶β 1 α 2 organization in which a dimeric p38 scaffold holds two LysRS α 2 dimers in a parallel configuration. Each of the N-terminal 48 residues of p38 binds one LysRS dimer and, in so doing, brings two copies of the LysRS dimer into the MSC. The results suggest that this unique geometry, which reconfigures the LysRS tetramer from α 2 ∶α 2 to α 2 β 1 ∶β 1 α 2 , is designed to control both retention and mobilization of LysRS from the MSC.noncanonical function | p38/AIMP2 | structural plasticity

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Section: Discussionmentioning

confidence: 99%

Structural context for mobilization of a human tRNA synthetase from its cytoplasmic complex

Fang

Zhang

Shapiro

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Rabbit reticulocytes were purchased from Green Hectare. The synthetase complex was purified from rabbit reticulocytes as described previously (29). Ethidium bromide, trifluoroethanol, octadecaphosphate, soluble calf thymus DNA, and ribonuclease were obtained from Sigma.…”

Section: Methodsmentioning

confidence: 99%

Magnesium Ion-mediated Binding to tRNA by an Amino-terminal Peptide of a Class II tRNA Synthetase

Hammamieh

Yang

2001

Journal of Biological Chemistry

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Aspartyl-tRNA synthetase is a class II tRNA synthetase and occurs in a multisynthetase complex in mammalian cells. Human Asp-tRNA synthetase contains a short 32-residue amino-terminal extension that can control the release of charged tRNA and its direct transfer to elongation factor 1␣; however, whether the extension binds to tRNA directly or interacts with the synthetase active site is not known. Full-length human AspRS, but not amino-terminal 32 residue-deleted, fully active AspRS, was found to bind to noncognate tRNA fMet in the presence of Mg 2؉ . Synthetic amino-terminal peptides bound similarly to tRNA fMet , whereas little or no binding of polynucleotides, poly(dA-dT), or polyphosphate to the peptides was found. The apparent binding constants to tRNA by the peptide increased with increasing concentrations of Mg 2؉ , suggesting Mg 2؉ mediates the binding as a new mode of RNA⅐peptide interactions. The binding of tRNA fMet to amino-terminal peptides was also observed using fluorescence-labeled tRNAs and circular dichroism. These results suggest that a small peptide can bind to tRNA selectively and that evolution of class II tRNA synthetases may involve structural changes of amino-terminal extensions for enhanced selective binding of tRNA.Aminoacyl-tRNA synthetases catalyze the covalent attachments of amino acids to cognate tRNAs in the first step of protein biosynthesis. Extensive studies of the structure and function of this family of enzymes have provided excellent understanding of fundamental principles of RNA-protein interactions and structures of synthetases. Almost all synthetases contain a core catalytic domain carrying out adenylation of an amino acid and an anti-codon binding domain essential for aminoacylation of cognate tRNA. The core catalytic domains in class I synthetases resemble dinucleotide binding folds and reside in the amino termini, whereas a seven-stranded antiparallel sheet with three ␣-helices characterizes active sites in class II synthetases and locates in the carboxyl termini of synthetases.Beyond the basic amino-and carboxyl-terminal catalytic domains, eukaryotic and mammalian synthetases (1-3) have evolved idiosyncratic extensions dispensable for aminoacylation of tRNA. Additionally, extensive association of synthetases occurs in high eukaryotic organisms; thus, 9 of the 20 synthetases associate as a multienzyme complex, ProRS and GluRS form a fused GluProRS (4, 5), and ValRS associates with the EF1H as a separate complex (6, 7). The function of the extensions in synthetases has attracted more attention recently. Controlled proteolysis or hydrophobic interaction chromatography dissociates several synthetases from the synthetase complex without significantly affecting enzymatic activities (8, 9); thus, the extensions in mammalian synthetases likely play pivotal roles in the structural organization of the synthetase complex. Extensions in synthetases can be involved in RNA binding (10, 11) or function as cytokines (12)(13)(14). It appears that extensions in synthetases are multifun...

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“…The synthetase complex was purified from Sprague-Dawley young male rats according to Kellermann et al [1], with modifications [14]. The synthetase complex was pyridine ethylated [15].…”

Section: Methodsmentioning

confidence: 99%

Proteolytic signal sequences (PEST) in the mammalian aminoacyl‐tRNA synthetase complex

et al. 1988

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Eight aminoacyl-tRNA synthetases together with three unidentified proteins are associated as a multi-enzyme complex in mammalian cells. Partial peptide sequences for lysyl-and aspartyl-tRNA synthetases are determined and no highly hydrophobic peptides are found. The partial amino acid sequences for two of the unidentified proteins in the complex are shown to have substantial homology and each has a number of unique sequences. The results suggest that the two unidentified proteins are fragments of synthetases. The partial sequences revealed the presence of PEST sequences in at least three proteins. Inasmuch as PEST sequences are signals for intracellular degradation, the mammalian synthetase complex may have evolved to protect these synthetases against intracellular proteolysis.Aminoacyl-tRNA synthetase; Multi-enzyme complex; Amino acid sequence

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Structural organization of the multienzyme complex of mammalian aminoacyl-tRNA synthetases

Cited by 35 publications

References 42 publications

Structural context for mobilization of a human tRNA synthetase from its cytoplasmic complex

Structural context for mobilization of a human tRNA synthetase from its cytoplasmic complex

Magnesium Ion-mediated Binding to tRNA by an Amino-terminal Peptide of a Class II tRNA Synthetase

Proteolytic signal sequences (PEST) in the mammalian aminoacyl‐tRNA synthetase complex

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