title: Requirement of rRNA methylation for 80S ribosome assembly on a cohort of cellular internal ribosome entry sites.
abstract: Protein syntheses mediated by cellular and viral internal ribosome entry sites (IRESs) are believed to have many features in common. Distinct mechanisms for ribosome recruitment and preinitiation complex assembly between the two processes have not been identified thus far. Here we show that the methylation status of rRNA differentially influenced the mechanism of 80S complex formation on IRES elements from the cellular sodium-coupled neutral amino acid transporter 2 (SNAT2) versus the hepatitis C virus mRNA. Translation initiation involves the assembly of the 48S preinitiation complex, followed by joining of the 60S ribosomal subunit and formation of the 80S complex. Abrogation of rRNA methylation did not affect the 48S complex but resulted in impairment of 80S complex assembly on the cellular, but not the viral, IRESs tested. Impairment of 80S complex assembly on the amino acid transporter SNAT2 IRES was rescued by purified 60S subunits containing fully methylated rRNA. We found that rRNA methylation did not affect the activity of any of the viral IRESs tested but affected the activity of numerous cellular IRESs. This work reveals a novel mechanism operating on a cohort of cellular IRESs that involves rRNA methylation for proper 80S complex assembly and efficient translation initiation.
authors.affiliation: Center for Gene Regulation in Health and Disease, Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Basu
authors.forename: Priyanka
authors.initials: P
authors.lastname: Das
authors.forename: Sujan
authors.initials: S
authors.lastname: Chaudhuri
authors.forename: Elena
authors.initials: E
authors.lastname: Bevilacqua
authors.forename: Joel
authors.initials: J
authors.lastname: Andrews
authors.forename: Sailen
authors.initials: S
authors.lastname: Barik
authors.forename: Maria
authors.initials: M
authors.lastname: Hatzoglou
authors.forename: Anton A
authors.initials: AA
authors.lastname: Komar
authors.forename: Barsanjit
authors.initials: B
authors.lastname: Mazumder
mesh_terms: D026924:Amino Acid Transport System A / Q000235:genetics / Q000378:metabolism*; D027201:Cationic Amino Acid Transporter 1 / Q000096:biosynthesis; D057809:HEK293 Cells; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics; D006801:Humans; D008745:Methylation; D010442:Peptide Chain Initiation, Translational; D014176:Protein Biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000096:biosynthesis; D054657:Ribosome Subunits / Q000737:chemistry / Q000378:metabolism*; D054658:Ribosome Subunits, Large / Q000378:metabolism; D054679:Ribosome Subunits, Small / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D026924:Amino Acid Transport System A; D027201:Cationic Amino Acid Transporter 1; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012367:RNA, Viral; D012269:Ribosomal Proteins; C498797:SLC38A2 protein, human; C420825:SLC7A1 protein, human