Peroxin Pex21p interacts with the C-terminal noncatalytic domain of yeast seryl-tRNA synthetase and forms a specific ternary complex with tRNA(Ser).
The seryl-tRNA synthetase from Saccharomyces cerevisiae interacts with the peroxisome biogenesis-related factor Pex21p. Several deletion mutants of seryl-tRNA synthetase were constructed and inspected for their ability to interact with Pex21p in a yeast two-hybrid assay, allowing mapping of the synthetase domain required for complex assembly. Deletion of the 13 C-terminal amino acids abolished Pex21p binding to seryl-tRNA synthetase. The catalytic parameters of purified truncated seryl-tRNA synthetase, determined in the serylation reaction, were found to be almost identical to those of the native enzyme. In vivo loss of interaction with Pex21p was confirmed in vitro by coaffinity purification. These data indicate that the C-terminally appended domain of yeast seryl-tRNA synthetase does not participate in substrate binding, but instead is required for association with Pex21p. We further determined that Pex21p does not directly bind tRNA, and nor does it possess a tRNA-binding motif, but it instead participates in the formation of a specific ternary complex with seryl-tRNA synthetase and tRNA(Ser), strengthening the interaction of seryl-tRNA synthetase with its cognate tRNA(Ser).
Godinic
Vlatka
V
Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia.
Mocibob
Marko
M
Rocak
Sanda
S
Ibba
Michael
M
Weygand-Durasevic
Ivana
I
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D012362:RNA, Transfer, Ser / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D016415:Sequence Alignment; D012714:Serine-tRNA Ligase / Q000378:metabolism*
D002352:Carrier Proteins; C116846:PEX21 protein, S cerevisiae; D012362:RNA, Transfer, Ser; D029701:Saccharomyces cerevisiae Proteins; D012714:Serine-tRNA Ligase