6NF8

Structure of human mitochondrial translation initiation factor 3 bound to the small ribosomal subunit -Class I

Summary for 6NF8

• Entry DOI: 10.2210/pdb6nf8/pdb
• Related: 3JD5
• EMDB information: 9362
• Descriptor: 28S ribosomal RNA, mitochondria, 28S ribosomal protein S27, mitochondrial, 28S ribosomal protein S34, mitochondrial, ... (32 entities in total)
• Functional Keywords: mitochondrial translation initiation factor 3, ribosomal protein
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 32
• Total formula weight: 1143408.54

Authors

Sharma, M.,Koripella, R.,Agrawal, R. (deposition date: 2018-12-19, release date: 2019-02-27, Last modification date: 2024-10-23)

Primary citation

Koripella, R.K.,Sharma, M.R.,Haque, M.E.,Risteff, P.,Spremulli, L.L.,Agrawal, R.K.
Structure of Human Mitochondrial Translation Initiation Factor 3 Bound to the Small Ribosomal Subunit.
iScience, 12:76-86, 2019

PubMed Abstract: The human mitochondrial translational initiation factor 3 (IF3) carries mitochondrial-specific amino acid extensions at both its N and C termini (N- and C-terminal extensions [NTE and CTE, respectively]), when compared with its eubacterial counterpart. Here we present 3.3- to 3.5-Å-resolution cryoelectron microscopic structures of the mammalian 28S mitoribosomal subunit in complex with human IF3. Unique contacts observed between the 28S subunit and N-terminal domain of IF3 explain its unusually high affinity for the 28S subunit, whereas the position of the mito-specific NTE suggests NTE's role in binding of initiator tRNA to the 28S subunit. The location of the C-terminal domain (CTD) clarifies its anti-association activity, whereas the orientation of the mito-specific CTE provides a mechanistic explanation for its role in destabilizing initiator tRNA in the absence of mRNA. Furthermore, our structure hints at a possible role of the CTD in recruiting leaderless mRNAs for translation initiation. Our findings highlight unique features of IF3 in mitochondrial translation initiation.

PubMed: 30677741
DOI: 10.1016/j.isci.2018.12.030

Experimental method

ELECTRON MICROSCOPY (3.48 Å)