7PUA image
Deposition Date 2021-09-29
Release Date 2022-03-02
Last Version Date 2024-11-13
Entry Detail
PDB ID:
7PUA
Keywords:
RIBOSOME
Title:
Middle assembly intermediate of the Trypanosoma brucei mitoribosomal small subunit
Biological Source:
Source Organism:
Trypanosoma brucei brucei (Taxon ID: 5702)
Method Details:
Experimental Method:
ELECTRON MICROSCOPY
Resolution:
3.60 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
7PUA validation report
Macromolecular Entities
Polymer Type:polyribonucleotide
Molecule:9S rRNA
Chain IDs:A (auth: CA)
Chain Length:602
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polyribonucleotide
Molecule:9S rRNA
Chain IDs:B (auth: CB)
Chain Length:3
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:uS3m
Chain IDs:C (auth: CC)
Chain Length:74
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Ribosomal_S5_C domain-containing protein
Gene (Uniprot):TbgDal_X7680
Chain IDs:D (auth: CE)
Chain Length:435
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A335 Pfam ID:PF03719
Protein Blast
Polymer Type:polypeptide(L)
Molecule:bS6m
Gene (Uniprot):Tb10.70.4850
Chain IDs:E (auth: CF)
Chain Length:160
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38BW5
Protein Blast
Polymer Type:polypeptide(L)
Molecule:30S ribosomal protein S8, putative
Gene (Uniprot):TbgDal_X16070
Chain IDs:F (auth: CH)
Chain Length:282
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZZU9 Pfam ID:PF00410
Protein Blast
Polymer Type:polypeptide(L)
Molecule:uS9m
Gene (Uniprot):Tb08.28F14.630
Chain IDs:G (auth: CI)
Chain Length:443
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57W62 Pfam ID:PF00380
Protein Blast
Polymer Type:polypeptide(L)
Molecule:LysM domain-containing protein
Gene (Uniprot):TbgDal_V5580
Chain IDs:H (auth: CJ)
Chain Length:257
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZPU0 Pfam ID:PF01476
Protein Blast
Polymer Type:polypeptide(L)
Molecule:uS11m
Gene (Uniprot):Tb10.406.0510
Chain IDs:I (auth: CK)
Chain Length:326
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q389T7
Polymer Type:polypeptide(L)
Molecule:uS12m
Chain IDs:J (auth: CL)
Chain Length:87
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Protein Blast
Polymer Type:polypeptide(L)
Molecule:uS14m
Gene (Uniprot):Tb08.29O9.64
Chain IDs:K (auth: CN)
Chain Length:166
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q580I0
Protein Blast
Polymer Type:polypeptide(L)
Molecule:uS15m
Gene (Uniprot):TB927.1.1200
Chain IDs:L (auth: CO)
Chain Length:429
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q4GZ99
Protein Blast
Polymer Type:polypeptide(L)
Molecule:bS16m
Gene (Uniprot):Tb11.02.5670
Chain IDs:M (auth: CP)
Chain Length:188
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q384N9
Protein Blast
Polymer Type:polypeptide(L)
Molecule:30S Ribosomal protein S17, putative
Gene (Uniprot):TbgDal_IX6740
Chain IDs:N (auth: CQ)
Chain Length:307
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZYU9 Pfam ID:PF00366
Protein Blast
Polymer Type:polypeptide(L)
Molecule:bS18m
Gene (Uniprot):TbgDal_X8370
Chain IDs:O (auth: CR)
Chain Length:320
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A3A4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:uS19m
Gene (Uniprot):DPX39_060024900
Chain IDs:P (auth: CS)
Chain Length:244
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6L621
Protein Blast
Polymer Type:polypeptide(L)
Molecule:bS21m
Gene (Uniprot):Tb03.26J7.200
Chain IDs:Q (auth: CU)
Chain Length:193
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q580M9
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS22
Gene (Uniprot):Tb09.211.2430
Chain IDs:R (auth: Ca)
Chain Length:602
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38DR3
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS23
Gene (Uniprot):TbgDal_V2060
Chain IDs:S (auth: Cb)
Chain Length:3
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZNU0
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS26
Gene (Uniprot):Tb09.211.3000
Chain IDs:T (auth: Cd)
Chain Length:440
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38DK6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS29
Gene (Uniprot):Tb06.3A7.780
Chain IDs:U (auth: Cg)
Chain Length:498
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q585C2 Pfam ID:PF10236
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS33
Gene (Uniprot):Tb03.27F10.720
Chain IDs:V (auth: Ci)
Chain Length:443
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57WW0
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS34
Gene (Uniprot):Tb08.5H5.370
Chain IDs:W (auth: Cj)
Chain Length:257
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57UK0
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS35
Gene (Uniprot):Tb11.47.0024
Chain IDs:X (auth: Ck)
Chain Length:326
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q387C7
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS37
Gene (Uniprot):Tb10.70.6600
Chain IDs:Y (auth: Cm)
Chain Length:215
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38C96
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS38
Gene (Uniprot):Tb07.29K4.740
Chain IDs:Z (auth: Cn)
Chain Length:166
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57VQ9
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Protein FYV4, mitochondrial
Gene (Uniprot):Tb10.26.0750
Chain IDs:AA (auth: Cp)
Chain Length:188
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q389L3
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS49
Gene (Uniprot):TbgDal_II2470
Chain IDs:BA (auth: DB)
Chain Length:1181
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZJE4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS50
Gene (Uniprot):DPX39_070040200
Chain IDs:CA (auth: DC)
Chain Length:1165
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6L3Q2
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS51
Gene (Uniprot):TbgDal_XI6210
Chain IDs:DA (auth: DD)
Chain Length:812
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A752
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS52
Gene (Uniprot):Tb11.02.0130
Chain IDs:EA (auth: DE)
Chain Length:747
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q386Q7
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS53
Gene (Uniprot):TbgDal_IX3440
Chain IDs:FA (auth: DF)
Chain Length:666
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZXX4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS54
Gene (Uniprot):TbgDal_V2500
Chain IDs:GA (auth: DG)
Chain Length:631
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZNY4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS55
Gene (Uniprot):DPX39_030051500
Chain IDs:HA (auth: DH)
Chain Length:581
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6LGC8
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS56
Gene (Uniprot):DPX39_060049600
Chain IDs:IA (auth: DI)
Chain Length:407
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6L6C6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS57
Gene (Uniprot):Tb06.4M18.330
Chain IDs:JA (auth: DJ)
Chain Length:396
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q584U8
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS58
Gene (Uniprot):DPX39_100041500
Chain IDs:KA (auth: DK)
Chain Length:324
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6L3U6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS59
Gene (Uniprot):TbgDal_X4100
Chain IDs:LA (auth: DL)
Chain Length:307
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A232
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS62
Gene (Uniprot):Tb11.01.3300
Chain IDs:MA (auth: DO)
Chain Length:282
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q383D1
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS63
Gene (Uniprot):TbgDal_IX2800
Chain IDs:NA (auth: DP)
Chain Length:274
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZXR0
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS65
Gene (Uniprot):TbgDal_V5090
Chain IDs:OA (auth: DR)
Chain Length:270
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZPP1
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Rhodanese domain-containing protein
Gene (Uniprot):Tb06.30P15.560
Chain IDs:PA (auth: DT)
Chain Length:247
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q586G5 Pfam ID:PF00581
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Ubiquitin-like domain-containing protein
Gene (Uniprot):TbgDal_III2230
Chain IDs:QA (auth: DU)
Chain Length:228
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZKC1 Pfam ID:PF00240
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS69
Gene (Uniprot):Tb08.4A8.150
Chain IDs:RA (auth: DV)
Chain Length:183
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57UZ6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS70
Gene (Uniprot):TbgDal_XI11660
Chain IDs:SA (auth: DW)
Chain Length:179
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A8P6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS71
Gene (Uniprot):Tb11.01.2920
Chain IDs:TA (auth: DX)
Chain Length:169
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q383G5
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS72
Gene (Uniprot):Tb07.13M20.50
Chain IDs:UA (auth: DY)
Chain Length:163
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57YD4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS73
Gene (Uniprot):Tb06.26G9.560
Chain IDs:VA (auth: DZ)
Chain Length:94
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q587C4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mS74
Gene (Uniprot):DPX39_100087100
Chain IDs:WA (auth: Da)
Chain Length:64
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6KY67
Protein Blast
Polymer Type:polypeptide(L)
Molecule:PPR_long domain-containing protein
Gene (Uniprot):TbgDal_I1800
Chain IDs:XA (auth: F2)
Chain Length:1024
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZIL7 Pfam ID:PF17177, PF13812, PF01535
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF3
Gene (Uniprot):Tb09.211.0950
Chain IDs:YA (auth: F3)
Chain Length:966
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38E61
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF5
Gene (Uniprot):TbgDal_XI17780
Chain IDs:ZA (auth: F5)
Chain Length:754
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0AAF7
Protein Blast
Polymer Type:polypeptide(L)
Molecule:DUF4460 domain-containing protein
Gene (Uniprot):Tb09.160.1280
Chain IDs:AB (auth: F6)
Chain Length:676
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38FQ8 Pfam ID:PF14687
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF7
Gene (Uniprot):Tb08.4A8.560
Chain IDs:BB (auth: F7)
Chain Length:679
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57UW6
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF9
Gene (Uniprot):TbgDal_VII3420
Chain IDs:CB (auth: F9)
Chain Length:607
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZSL5
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF21
Gene (Uniprot):TbgDal_III650
Chain IDs:DB (auth: FM), EB (auth: FN)
Chain Length:370
Number of Molecules:2
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZJW2 Pfam ID:PF03446, PF14833
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF22
Gene (Uniprot):Tb10.26.0050
Chain IDs:FB (auth: FO)
Chain Length:334
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q389F9
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF23
Gene (Uniprot):TbgDal_XI13330
Chain IDs:GB (auth: FP)
Chain Length:349
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A963
Protein Blast
Polymer Type:polypeptide(L)
Molecule:LMWPc domain-containing protein
Gene (Uniprot):Tb09.160.2100
Chain IDs:HB (auth: FW)
Chain Length:263
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38FI3 Pfam ID:PF01451
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF27
Gene (Uniprot):Tb08.11J15.790
Chain IDs:IB (auth: FX)
Chain Length:239
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57YK5 Pfam ID:PF13812
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF29
Gene (Uniprot):DPX39_100090900
Chain IDs:JB (auth: FZ)
Chain Length:178
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:A0A3L6KWY8
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF31
Gene (Uniprot):Tb04.2L9.550
Chain IDs:KB (auth: Fb)
Chain Length:151
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q581U4
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Acyl carrier protein
Gene (Uniprot):Tb03.27F10.580
Chain IDs:LB (auth: Fc)
Chain Length:148
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q57WW9 Pfam ID:PF00550
Protein Blast
Polymer Type:polypeptide(L)
Molecule:DUF4379 domain-containing protein
Gene (Uniprot):Tb04.2L9.680
Chain IDs:MB (auth: Fd)
Chain Length:143
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q581T4 Pfam ID:PF14311
Protein Blast
Polymer Type:polypeptide(L)
Molecule:DNA photolyase, putative
Gene (Uniprot):TbgDal_XI13790
Chain IDs:NB (auth: Ff)
Chain Length:848
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A9A9 Pfam ID:PF00875, PF03441
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Acyl transferase-like protein, putative
Gene (Uniprot):TbgDal_IX7190
Chain IDs:OB (auth: Fg)
Chain Length:550
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZYZ4 Pfam ID:PF00698
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF37
Gene (Uniprot):Tb10.6k15.1310
Chain IDs:PB (auth: Fh)
Chain Length:318
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:Q38A63
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF38
Gene (Uniprot):TbgDal_V2410
Chain IDs:QB (auth: Fi)
Chain Length:629
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZNX5
Protein Blast
Polymer Type:polypeptide(L)
Molecule:Translation initiation factor IF-2, putative
Gene (Uniprot):TbgDal_VII3600
Chain IDs:RB (auth: IA)
Chain Length:787
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:C9ZSN7 Pfam ID:PF00009, PF22042
Protein Blast
Polymer Type:polypeptide(L)
Molecule:mt-SAF39
Gene (Uniprot):TbgDal_X19700
Chain IDs:SB (auth: IB)
Chain Length:803
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
UniProt ID:D0A0V4
Polymer Type:polypeptide(L)
Molecule:Unk8
Chain IDs:TB (auth: U8)
Chain Length:30
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkC
Chain IDs:UB (auth: UC)
Chain Length:9
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkD
Chain IDs:VB (auth: UD)
Chain Length:13
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkF
Chain IDs:WB (auth: UF)
Chain Length:36
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkG
Chain IDs:XB (auth: UG)
Chain Length:271
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkI
Chain IDs:YB (auth: UI)
Chain Length:6
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkK
Chain IDs:ZB (auth: UK)
Chain Length:24
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:Unk
Chain IDs:AC (auth: UM), BC (auth: UN), DC (auth: UQ)
Chain Length:8
Number of Molecules:3
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:UnkP
Chain IDs:CC (auth: UP)
Chain Length:32
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:Unka
Chain IDs:EC (auth: Ua)
Chain Length:10
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Polymer Type:polypeptide(L)
Molecule:Unkg
Chain IDs:FC (auth: Ug)
Chain Length:271
Number of Molecules:1
Biological Source:Trypanosoma brucei brucei
Ligand Molecules
ATP
FDA
GDP
MG
PM8
PO4
ZN
Primary Citation
Mitoribosomal small subunit maturation involves formation of initiation-like complexes.
Proc.Natl.Acad.Sci.USA 119 ? ? (2022)
PMID: 35042777 DOI: 10.1073/pnas.2114710118

Abstact

Mitochondrial ribosomes (mitoribosomes) play a central role in synthesizing mitochondrial inner membrane proteins responsible for oxidative phosphorylation. Although mitoribosomes from different organisms exhibit considerable structural variations, recent insights into mitoribosome assembly suggest that mitoribosome maturation follows common principles and involves a number of conserved assembly factors. To investigate the steps involved in the assembly of the mitoribosomal small subunit (mt-SSU) we determined the cryoelectron microscopy structures of middle and late assembly intermediates of the Trypanosoma brucei mitochondrial small subunit (mt-SSU) at 3.6- and 3.7-Å resolution, respectively. We identified five additional assembly factors that together with the mitochondrial initiation factor 2 (mt-IF-2) specifically interact with functionally important regions of the rRNA, including the decoding center, thereby preventing premature mRNA or large subunit binding. Structural comparison of assembly intermediates with mature mt-SSU combined with RNAi experiments suggests a noncanonical role of mt-IF-2 and a stepwise assembly process, where modular exchange of ribosomal proteins and assembly factors together with mt-IF-2 ensure proper 9S rRNA folding and protein maturation during the final steps of assembly.

Legend

Protein

Chemical

Disease

Primary Citation of related structures
7PUA