Small ribosomal subunit protein uS4 (30S ribosomal protein S4) of Pseudomonas aeruginosa PAO1. uS4 is a primary 16S rRNA-binding protein that nucleates early assembly of the 30S ribosomal subunit body. It binds directly to 16S rRNA, inducing conformational rearrangements required for recruitment of secondary and tertiary binding proteins. In the mature 30S subunit, uS4 contributes to translational accuracy through its interface with uS5; disruption of this interface during tRNA selection controls the transition between open and closed conformations of the decoding center. The protein belongs to the universal ribosomal protein uS4 family and contains an N-terminal domain and a C-terminal S4 RNA-binding domain.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003735 structural constituent of ribosome | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation inferred from phylogenetic analysis (PANTHER). uS4 is a stable, stoichiometric component of the 30S ribosomal subunit whose primary molecular function is to provide structural integrity to the particle. It binds directly to 16S rRNA and is essential for 30S assembly and stability. The BioReason SFT functional summary (rpsD-deep-research-bioreason-sft.md) correctly identifies uS4 as a structural organizer of the small subunit. Reason: uS4 is unambiguously a structural constituent of the ribosome. It is one of the primary binding proteins of the 30S subunit and remains stably incorporated throughout the translation cycle. Multiple cryo-EM structures confirm its integral position in the 30S subunit. Supporting Evidence: PMID:28483689 ribosomal protein uS4 helps initiate the assembly of the small subunit by binding directly to 16S rRNA |
| GO:0015935 small ribosomal subunit | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for cellular component localization to the small ribosomal subunit. uS4 is a core component of the bacterial 30S subunit confirmed by multiple cryo-EM structures of the P. aeruginosa 70S ribosome (PDB 7UNR, 7UNV, 7UNW, 8RWG). Reason: uS4 is resolved in multiple cryo-EM structures of the P. aeruginosa 70S ribosome at 2.5-2.9 A resolution, confirming its stable incorporation into the 30S subunit. Supporting Evidence: PMID:28483689 ribosomal protein uS4 helps initiate the assembly of the small subunit by binding directly to 16S rRNA |
| GO:0019843 rRNA binding | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for rRNA binding. uS4 is one of the primary rRNA binding proteins of the 30S subunit, binding directly to the 16S rRNA where it nucleates assembly of the subunit body. Reason: rRNA binding is the central molecular function of uS4. It binds 16S rRNA directly and is one of the first proteins to associate with the rRNA during in vitro 30S reconstitution. This has been extensively characterized in E. coli and is conserved across bacteria. Supporting Evidence: PMID:17376481 Additionally, a temperature-dependent conformational rearrangement was reported for a complex of primary r-protein S4 and 16 S rRNA PMID:28483689 ribosomal protein uS4 helps initiate the assembly of the small subunit by binding directly to 16S rRNA |
| GO:0042274 ribosomal small subunit biogenesis | IBA GO_REF:0000033 | ACCEPT | Summary: IBA annotation for ribosomal small subunit biogenesis. uS4 is a primary binding protein that initiates the 30S assembly pathway by binding 16S rRNA and inducing conformational changes that enable recruitment of downstream assembly proteins. Reason: uS4 is essential for 30S biogenesis as one of the primary binding proteins that nucleates assembly. Temperature-dependent conformational rearrangements of the S4-16S rRNA complex are required for downstream assembly events. C-terminal truncations of uS4 cause assembly defects. Supporting Evidence: PMID:17376481 Some of the architectures achieved in these rearrangements are consistent with subsequent downstream assembly events such as assembly of the secondary and tertiary binding r-proteins PMID:28483689 the C-terminal requirements for ribosome assembly are less rigid than for mRNA decoding |
| GO:0003723 RNA binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: IEA annotation from InterPro2GO mapping (IPR002942 S4 RNA-binding domain and IPR036986 S4 RNA-binding domain superfamily). RNA binding is correct but less specific than rRNA binding (GO:0019843) which is already annotated. Reason: The S4 RNA-binding domain does indeed confer RNA binding activity. However, the more specific rRNA binding (GO:0019843) is already annotated via IBA and IEA evidence. This general RNA binding annotation is redundant with the more specific term but not incorrect; uS4 also has mRNA binding activity as a translational autorepressor in E. coli. |
| GO:0003735 structural constituent of ribosome | IEA GO_REF:0000002 | ACCEPT | Summary: IEA annotation from InterPro2GO mapping (IPR005709 bacterial uS4 family). This duplicates the IBA annotation for the same term. Reason: Correct InterPro2GO mapping. The bacterial uS4 family (IPR005709) appropriately maps to structural constituent of ribosome. Consistent with the IBA annotation above. |
| GO:0006412 translation | IEA GO_REF:0000120 | ACCEPT | Summary: IEA annotation from combined automated methods (UniRule/InterPro). uS4 is an essential structural component of the 30S subunit required for translation. Reason: As a core 30S ribosomal protein, uS4 is directly involved in translation. The mature 30S subunit containing uS4 participates in mRNA decoding, and uS4 specifically contributes to translational accuracy via its interaction with uS5 at the decoding center. Supporting Evidence: PMID:25548247 Ribosomal proteins S4 and S5 participate in the decoding and assembly processes on the ribosome |
| GO:0015935 small ribosomal subunit | IEA GO_REF:0000002 | ACCEPT | Summary: IEA annotation from InterPro2GO mapping (IPR005709). Duplicates the IBA annotation for the same cellular component. Reason: Correct InterPro2GO mapping consistent with all structural and biochemical evidence for 30S subunit localization. |
| GO:0019843 rRNA binding | IEA GO_REF:0000120 | ACCEPT | Summary: IEA annotation from combined automated methods (UniRule mapping from IPR001912, IPR018079, IPR022801). Duplicates the IBA annotation for the same molecular function. Reason: Correct automated annotation. Multiple InterPro signatures for uS4 domains all point to rRNA binding as the core molecular function. |
| GO:0022627 cytosolic small ribosomal subunit | NAS PMID:28483689 The C-terminus of ribosomal protein uS4 contributes to small... | NEW | Summary: uS4 is a stable component of the bacterial cytosolic 30S ribosomal subunit. This is more specific than GO:0015935 (small ribosomal subunit) and accurately reflects that bacterial ribosomes are cytosolic. The BioReason SFT trace (rpsD-deep-research-bioreason-sft.md) also correctly infers cytosolic small ribosomal subunit localization. Reason: The existing annotations use GO:0015935 (small ribosomal subunit) which is correct but does not specify the cytosolic compartment. Since P. aeruginosa ribosomes are cytosolic, this more specific CC term is warranted. Supporting Evidence: PMID:28483689 ribosomal protein uS4 helps initiate the assembly of the small subunit by binding directly to 16S rRNA file:PSEAE/rpsD/rpsD-deep-research-bioreason-sft.md [BioReason inferred] cytosolic small ribosomal subunit (GO:0022627) |
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