TY - JOUR
T1 - The yeast protein Mam33 functions in the assembly of the mitochondrial ribosome
AU - Hillman, Gabrielle A.
AU - Henry, Michael F.
N1 - Funding Information:
This work was supported by NIGMS National Institutes of Health Grant GM117483 (to M. F. H.). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the respon-sibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Publisher Copyright:
© 2019 Lin et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2019/6/21
Y1 - 2019/6/21
N2 - Mitochondrial ribosomes are functionally specialized for the synthesis of several essential inner membrane proteins of the respiratory chain. Although remarkable progress has been made toward understanding the structure of mitoribosomes, the pathways and factors that facilitate their biogenesis remain largely unknown. The long unstructured domains of unassembled ribosomal proteins are highly prone to misfolding and often require dedicated chaperones to prevent aggregation. To date, chaperones that ensure safe delivery to the assembling ribosome have not been identified in the mitochondrion. In this study, a respiratory synthetic lethality screen revealed a role for an evolutionarily conserved mitochondrial matrix protein called Mam33 in Saccharomyces cerevisiae mitoribosome biogenesis. We found that the absence of Mam33 results in misassembled, aggregated ribosomes and a respiratory lethal phenotype in combination with other ribosome-assembly mutants. Using sucrose gradient sedimentation, native affinity purifications, in vitro binding assays, and SILAC-based quantitative proteomics, we found that Mam33 does not associate with the mature mitoribosome, but directly binds a subset of unassembled large subunit proteins. Based on these data, we propose that Mam33 binds specific mitoribosomal proteins to ensure proper assembly.
AB - Mitochondrial ribosomes are functionally specialized for the synthesis of several essential inner membrane proteins of the respiratory chain. Although remarkable progress has been made toward understanding the structure of mitoribosomes, the pathways and factors that facilitate their biogenesis remain largely unknown. The long unstructured domains of unassembled ribosomal proteins are highly prone to misfolding and often require dedicated chaperones to prevent aggregation. To date, chaperones that ensure safe delivery to the assembling ribosome have not been identified in the mitochondrion. In this study, a respiratory synthetic lethality screen revealed a role for an evolutionarily conserved mitochondrial matrix protein called Mam33 in Saccharomyces cerevisiae mitoribosome biogenesis. We found that the absence of Mam33 results in misassembled, aggregated ribosomes and a respiratory lethal phenotype in combination with other ribosome-assembly mutants. Using sucrose gradient sedimentation, native affinity purifications, in vitro binding assays, and SILAC-based quantitative proteomics, we found that Mam33 does not associate with the mature mitoribosome, but directly binds a subset of unassembled large subunit proteins. Based on these data, we propose that Mam33 binds specific mitoribosomal proteins to ensure proper assembly.
UR - http://www.scopus.com/inward/record.url?scp=85068254477&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85068254477&partnerID=8YFLogxK
U2 - 10.1074/jbc.RA119.008476
DO - 10.1074/jbc.RA119.008476
M3 - Article
C2 - 31053642
AN - SCOPUS:85068254477
SN - 0021-9258
VL - 294
SP - 9813
EP - 9829
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 25
ER -