TY - JOUR
T1 - Yeast cytoplasmic and mitochondrial methionyl-tRNA synthetases
T2 - Two structural frameworks for identical functions
AU - Senger, Bruno
AU - Despons, Laurence
AU - Walter, Philippe
AU - Jakubowski, Hieronim
AU - Fasiolo, Franco
N1 - Funding Information:
This work was supported by grants from the CNRS and the Association pour la Recherche sur le Cancer (F. F.) and the National Science Foundation, grant numbers MCB-9724929 and MCB-00989984 (H. J.). Supported by grants from the National Science Foundation (MCB-9724929 and MCB-0059984) and the Foundation of UMDNJ (Grant #22-02).
PY - 2001/8/3
Y1 - 2001/8/3
N2 - The yeast Saccharomyces cerevisiae possesses two methionyl-tRNA synthetases (MetRS), one in the cytoplasm and the other in mitochondria. The cytoplasmic MetRS has a zinc-finger motif of the type Cys-X2-Cys-X9-Cys-X2-Cys in an insertion domain that divides the nucleotide-binding fold into two halves, whereas no such motif is present in the mitochondrial MetRS. Here, we show that tightly bound zinc atom is present in the cytoplasmic MetRS but not in the mitochondrial MetRS. To test whether the presence of a zinc-binding site is required for cytoplasmic functions of MetRS, we constructed a yeast strain in which cytoplasmic MetRS gene was inactivated and the mitochondrial MetRS gene was expressed in the cytoplasm. Provided that methionine-accepting tRNA is overexpressed, this strain was viable, indicating that mitochondrial MetRS was able to aminoacylate tRNAMet in the cytoplasm. Site-directed mutagenesis demonstrated that the zinc domain was required for the stability and consequently for the activity of cytoplasmic MetRS. Mitochondrial MetRS, like cytoplasmic MetRS, supported homocysteine editing in vivo in the yeast cytoplasm. Both MetRSs catalyzed homocysteine editing and aminoacylation of coenzyme A in vitro. Thus, identical synthetic and editing functions can be carried out in different structural frameworks of cytoplasmic and mitochondrial MetRSs.
AB - The yeast Saccharomyces cerevisiae possesses two methionyl-tRNA synthetases (MetRS), one in the cytoplasm and the other in mitochondria. The cytoplasmic MetRS has a zinc-finger motif of the type Cys-X2-Cys-X9-Cys-X2-Cys in an insertion domain that divides the nucleotide-binding fold into two halves, whereas no such motif is present in the mitochondrial MetRS. Here, we show that tightly bound zinc atom is present in the cytoplasmic MetRS but not in the mitochondrial MetRS. To test whether the presence of a zinc-binding site is required for cytoplasmic functions of MetRS, we constructed a yeast strain in which cytoplasmic MetRS gene was inactivated and the mitochondrial MetRS gene was expressed in the cytoplasm. Provided that methionine-accepting tRNA is overexpressed, this strain was viable, indicating that mitochondrial MetRS was able to aminoacylate tRNAMet in the cytoplasm. Site-directed mutagenesis demonstrated that the zinc domain was required for the stability and consequently for the activity of cytoplasmic MetRS. Mitochondrial MetRS, like cytoplasmic MetRS, supported homocysteine editing in vivo in the yeast cytoplasm. Both MetRSs catalyzed homocysteine editing and aminoacylation of coenzyme A in vitro. Thus, identical synthetic and editing functions can be carried out in different structural frameworks of cytoplasmic and mitochondrial MetRSs.
KW - Homocysteine editing
KW - Methionyl-S-coenzyme A
KW - Methionyl-tRNA synthetase
KW - Yeast
KW - Zinc
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U2 - 10.1006/jmbi.2001.4844
DO - 10.1006/jmbi.2001.4844
M3 - Article
C2 - 11469869
AN - SCOPUS:0035800663
SN - 0022-2836
VL - 311
SP - 205
EP - 216
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 1
ER -