5ool
From Proteopedia
Structure of a native assembly intermediate of the human mitochondrial ribosome with unfolded interfacial rRNA
Structural highlights
Disease[RM03_HUMAN] Combined oxidative phosphorylation defect type 9. The disease is caused by mutations affecting the gene represented in this entry. [RM44_HUMAN] Infantile hypertrophic cardiomyopathy due to MRPL44 deficiency. The disease is caused by mutations affecting the gene represented in this entry. Function[RM18_HUMAN] Together with thiosulfate sulfurtransferase (TST), acts as a mitochondrial import factor for the cytosolic 5S rRNA. The precursor form shows RNA chaperone activity; is able to fold the 5S rRNA into an import-competent conformation that is recognized by rhodanese (TST). Both the cytoplasmic and mitochondrial forms are able to bind to the helix IV-loop D in the gamma domain of the 5S rRNA.[1] [ICT1_HUMAN] Essential peptidyl-tRNA hydrolase component of the mitochondrial large ribosomal subunit. Acts as a codon-independent translation release factor that has lost all stop codon specificity and directs the termination of translation in mitochondrion, possibly in case of abortive elongation. May be involved in the hydrolysis of peptidyl-tRNAs that have been prematurely terminated and thus in the recycling of stalled mitochondrial ribosomes.[2] [RM14_HUMAN] Forms part of 2 intersubunit bridges in the assembled ribosome. Upon binding to MALSU1 intersubunit bridge formation is blocked, preventing ribosome formation and repressing translation (Probable).[3] [RM36_HUMAN] Component of the large subunit of the mitochondrial ribosome. [G45IP_HUMAN] Acts as a negative regulator of G1 to S cell cycle phase progression by inhibiting cyclin-dependent kinases. Inhibitory effects are additive with GADD45 proteins but occurs also in the absence of GADD45 proteins. Acts as a repressor of the orphan nuclear receptor NR4A1 by inhibiting AB domain-mediated transcriptional activity. May be involved in the hormone-mediated regulation of NR4A1 transcriptional activity. May play a role in mitochondrial protein synthesis. [RM16_HUMAN] Component of the large subunit of mitochondrial ribosome. [RM41_HUMAN] Component of the mitochondrial ribosome large subunit. Also involved in apoptosis and cell cycle. Enhances p53/TP53 stability, thereby contributing to p53/TP53-induced apoptosis in response to growth-inhibitory condition. Enhances p53/TP53 translocation to the mitochondria. Has the ability to arrest the cell cycle at the G1 phase, possibly by stabilizing the CDKN1A and CDKN1B (p27Kip1) proteins.[4] [5] [ACPM_HUMAN] Carrier of the growing fatty acid chain in fatty acid biosynthesis in mitochondria. Accessory and non-catalytic subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), which functions in the transfer of electrons from NADH to the respiratory chain (By similarity). [RM44_HUMAN] Component of the 39S subunit of mitochondrial ribosome. May have a function in the assembly/stability of nascent mitochondrial polypeptides exiting the ribosome.[6] [MASU1_HUMAN] May function as a ribosomal silencing factor. Addition to isolated mitochondrial ribosomal subunits partially inhibits translation. Interacts with mitochondrial ribosomal protein L14 (MRPL14), probably blocking formation of intersubunit bridge B8, preventing association of the 28S and 39S ribosomal subunits and the formation of functional ribosomes, thus repressing translation. May also participate in the assembly and/or regulation of the stability of the large subunit of the mitochondrial ribosome.[7] Publication Abstract from PubMedMammalian mitochondrial ribosomes (mitoribosomes) have less rRNA content and 36 additional proteins compared with the evolutionarily related bacterial ribosome. These differences make the assembly of mitoribosomes more complex than the assembly of bacterial ribosomes, but the molecular details of mitoribosomal biogenesis remain elusive. Here, we report the structures of two late-stage assembly intermediates of the human mitoribosomal large subunit (mt-LSU) isolated from a native pool within a human cell line and solved by cryo-EM to approximately 3-A resolution. Comparison of the structures reveals insights into the timing of rRNA folding and protein incorporation during the final steps of ribosomal maturation and the evolutionary adaptations that are required to preserve biogenesis after the structural diversification of mitoribosomes. Furthermore, the structures redefine the ribosome silencing factor (RsfS) family as multifunctional biogenesis factors and identify two new assembly factors (L0R8F8 and mt-ACP) not previously implicated in mitoribosomal biogenesis. Structures of the human mitochondrial ribosome in native states of assembly.,Brown A, Rathore S, Kimanius D, Aibara S, Bai XC, Rorbach J, Amunts A, Ramakrishnan V Nat Struct Mol Biol. 2017 Sep 11. doi: 10.1038/nsmb.3464. PMID:28892042[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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