4v5b

Structural highlights

Function

[RL31_ECO57] Binds the 23S rRNA. [RL18_ECOLI] This is one of the proteins that mediates the attachment of the 5S rRNA subcomplex onto the large ribosomal subunit where it forms part of the central protuberance. Binds stably to 5S rRNA; increases binding abilities of L5 in a cooperative fashion; both proteins together confer 23S rRNA binding. The 5S rRNA and some of its associated proteins might help stabilize positioning of ribosome-bound tRNAs.^[1] [RL23_ECOUT] One of the early assembly proteins it binds 23S rRNA. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the ribosome. Forms the main docking site for trigger factor binding to the ribosome (By similarity). [RL15_ECOLI] This protein binds the 5S rRNA. It is required for the late stages of subunit assembly, and is essential for 5S rRNA assembly onto the ribosome.[HAMAP-Rule:MF_01341_B] [RL13_ECOUT] This protein is one of the early assembly proteins of the 50S ribosomal subunit, although it is not seen to bind rRNA by itself. It is important during the early stages of 50S assembly (By similarity). [RS12_ECOLI] With S4 and S5 plays an important role in translational accuracy.[HAMAP-Rule:MF_00403_B] Interacts with and stabilizes bases of the 16S rRNA that are involved in tRNA selection in the A site and with the mRNA backbone. Located at the interface of the 30S and 50S subunits, it traverses the body of the 30S subunit contacting proteins on the other side and probably holding the rRNA structure together. The combined cluster of proteins S8, S12 and S17 appears to hold together the shoulder and platform of the 30S subunit (By similarity).[HAMAP-Rule:MF_00403_B] Cryo-EM studies suggest that S12 contacts the EF-Tu bound tRNA in the A-site during codon-recognition. This contact is most likely broken as the aminoacyl-tRNA moves into the peptidyl transferase center in the 50S subunit.[HAMAP-Rule:MF_00403_B] [RL24_ECO57] One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit.[HAMAP-Rule:MF_01326] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit.[HAMAP-Rule:MF_01326] [RL3_ECOL6] One of the primary rRNA binding proteins, it binds directly near the 3'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit. [RS3_ECOL6] Binds the lower part of the 30S subunit head. Binds mRNA in the 70S ribosome, positioning it for translation (By similarity). [RL4_ECO57] One of the primary rRNA binding proteins, this protein initially binds near the 5'-end of the 23S rRNA. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.[HAMAP-Rule:MF_01328] Protein L4 is a both a transcriptional repressor and a translational repressor protein. It regulates transcription of the S10 operon (to which L4 belongs) by causing premature termination of transcription within the S10 leader. L4 controls the translation of the S10 operon by binding to its mRNA (By similarity). Forms part of the polypeptide exit tunnel.[HAMAP-Rule:MF_01328] [RS16_ECOLI] In addition to being a ribosomal protein, S16 also has a cation-dependent endonuclease activity.^[2] In-frame fusions with the ribosome maturation factor rimM suppress mutations in the latter (probably due to increased rimM expression) and are found in translationally active 70S ribosomes.^[3] [RS18_ECOLI] Binds as a heterodimer with protein S6 to the central domain of the 16S rRNA, where it helps stabilize the platform of the 30S subunit.[HAMAP-Rule:MF_00270] [RS7_ECOL6] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the head domain of the 30S subunit. Is located at the subunit interface close to the decoding center, probably blocks exit of the E-site tRNA.[HAMAP-Rule:MF_00480] [RS9_ECOLI] The C-terminal tail plays a role in the affinity of the 30S P site for different tRNAs. Mutations that decrease this affinity are suppressed in the 70S ribosome.^[4] [RL5_ECO57] This is 1 of the proteins that binds and probably mediates the attachment of the 5S RNA into the large ribosomal subunit, where it forms part of the central protuberance. In the 70S ribosome it contacts protein S13 of the 30S subunit (bridge B1b), connecting the 2 subunits; this bridge is implicated in subunit movement. Contacts the P site tRNA; the 5S rRNA and some of its associated proteins might help stabilize positioning of ribosome-bound tRNAs.[HAMAP-Rule:MF_01333] [RL11_ECOL6] Forms part of the ribosomal stalk which helps the ribosome interact with GTP-bound translation factors.[HAMAP-Rule:MF_00736] [RS20_ECOL5] Binds directly to 16S ribosomal RNA (By similarity). [RS13_ECO57] Located at the top of the head of the 30S subunit, it contacts several helices of the 16S rRNA. In the E.coli 70S ribosome in the initiation state it has been modeled to contact the 23S rRNA (bridge B1a) and protein L5 of the 50S subunit (bridge B1b), connecting the 2 subunits; bridge B1a is broken in the model with bound EF-G, while the protein-protein contacts between S13 and L5 in B1b change. Contacts the tRNAs in the A and P sites (By similarity). [RL16_ECOLI] This protein binds directly to 23S ribosomal RNA and is located at the A site of the peptidyltransferase center. It contacts the A and P site tRNAs. It has an essential role in subunit assembly, which is not well understood.[HAMAP-Rule:MF_01342] [RL14_ECOUT] Binds to 23S rRNA. Forms part of two intersubunit bridges in the 70S ribosome (By similarity). [RL29_ECOL6] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit. [RL22_ECOL6] This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g. L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome (By similarity). The globular domain of the protein is located near the polypeptide exit tunnel on the outside of the subunit, while an extended beta-hairpin is found that lines the wall of the exit tunnel in the center of the 70S ribosome. [RL25_ECOLI] This is one of the proteins that binds to the 5S RNA in the ribosome where it forms part of the central protuberance. Binds to the 5S rRNA independently of L5 and L18. Not required for binding of the 5S rRNA/L5/L18 subcomplex to 23S rRNA.[HAMAP-Rule:MF_01336] [RS8_ECOK1] One of the primary rRNA binding proteins, it binds directly to 16S rRNA central domain where it helps coordinate assembly of the platform of the 30S subunit (By similarity). [RL9_ECOLI] One of the primary rRNA binding proteins, it binds very close to the 3' end of the 23S rRNA.[HAMAP-Rule:MF_00503] [RS17_ECOUT] One of the primary rRNA binding proteins, it binds specifically to the 5'-end of 16S ribosomal RNA (By similarity). [RL21_ECOL5] This protein binds to 23S rRNA in the presence of protein L20 (By similarity). [RL19_ECOLI] This protein is located at the 30S-50S ribosomal subunit interface. In the 70S ribosome (PubMed:12809609) it has been modeled to make two contacts with the 16S rRNA of the 30S subunit forming part of bridges B6 and B8. In the 3.5 A resolved structures (PubMed:16272117) L14 and L19 interact and together make contact with the 16S rRNA. The protein conformation is quite different between the 50S and 70S structures, which may be necessary for translocation.[HAMAP-Rule:MF_00402] [RS10_ECOLI] Involved in the binding of tRNA to the ribosomes.[HAMAP-Rule:MF_00508] [RS14_ECOLI] Binds 16S rRNA, required for the assembly of 30S particles and may also be responsible for determining the conformation of the 16S rRNA at the A site.[HAMAP-Rule:MF_00537] [RL20_ECOLI] One of the primary rRNA binding proteins, it binds close to the 5'-end of the 23S rRNA. It is important during the early stages of 50S assembly.[HAMAP-Rule:MF_00382] [RL6_ECO57] This protein binds to the 23S rRNA, and is important in its secondary structure. It is located near the subunit interface in the base of the L7/L12 stalk, and near the tRNA binding site of the peptidyltransferase center (By similarity). [DEF_ECOLI] Removes the formyl group from the N-terminal Met of newly synthesized proteins. Requires at least a dipeptide for an efficient rate of reaction. N-terminal L-methionine is a prerequisite for activity but the enzyme has broad specificity at other positions.[HAMAP-Rule:MF_00163] [RS4_ECOL5] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit (By similarity). With S5 and S12 plays an important role in translational accuracy (By similarity). [RL2_ECO57] One of the primary rRNA binding proteins. Required for association of the 30S and 50S subunits to form the 70S ribosome, for tRNA binding and peptide bond formation. It has been suggested to have peptidyltransferase activity; this is somewhat controversial. Makes several contacts with the 16S rRNA in the 70S ribosome.[HAMAP-Rule:MF_01320] [RS19_ECOL5] Protein S19 forms a complex with S13 that binds strongly to the 16S ribosomal RNA (By similarity). [RS15_ECO57] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it helps nucleate assembly of the platform of the 30S subunit by binding and bridging several RNA helices of the 16S rRNA (By similarity). Forms an intersubunit bridge (bridge B4) with the 23S rRNA of the 50S subunit in the ribosome (By similarity). [RS6_ECOL6] Binds together with S18 to 16S ribosomal RNA. [RS5_ECOLI] With S4 and S12 plays an important role in translational accuracy. Many suppressors of streptomycin-dependent mutants of protein S12 are found in this protein, some but not all of which decrease translational accuracy (ram, ribosomal ambiguity mutations).^[5] Located at the back of the 30S subunit body where it stabilizes the conformation of the head with respect to the body.^[6] The physical location of this protein suggests it may also play a role in mRNA unwinding by the ribosome, possibly by forming part of a processivity clamp.^[7] [RS11_ECOK1] Located on the platform of the 30S subunit, it bridges several disparate RNA helices of the 16S rRNA. Forms part of the Shine-Dalgarno cleft in the 70S ribosome (By similarity).

See Also

• Ribosome 3D structures

References

1. ↑ Newberry V, Brosius J, Garrett R. Fragment of protein L18 from the Escherichia coli ribosome that contains the 5S RNA binding site. Nucleic Acids Res. 1978 Jun;5(6):1753-66. PMID:353728
2. ↑ Oberto J, Bonnefoy E, Mouray E, Pellegrini O, Wikstrom PM, Rouviere-Yaniv J. The Escherichia coli ribosomal protein S16 is an endonuclease. Mol Microbiol. 1996 Mar;19(6):1319-30. PMID:8730873
3. ↑ Oberto J, Bonnefoy E, Mouray E, Pellegrini O, Wikstrom PM, Rouviere-Yaniv J. The Escherichia coli ribosomal protein S16 is an endonuclease. Mol Microbiol. 1996 Mar;19(6):1319-30. PMID:8730873
4. ↑ Hoang L, Fredrick K, Noller HF. Creating ribosomes with an all-RNA 30S subunit P site. Proc Natl Acad Sci U S A. 2004 Aug 24;101(34):12439-43. Epub 2004 Aug 12. PMID:15308780 doi:10.1073/pnas.0405227101
5. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
6. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
7. ↑ Takyar S, Hickerson RP, Noller HF. mRNA helicase activity of the ribosome. Cell. 2005 Jan 14;120(1):49-58. PMID:15652481 doi:10.1016/j.cell.2004.11.042
8. ↑ Bingel-Erlenmeyer R, Kohler R, Kramer G, Sandikci A, Antolic S, Maier T, Schaffitzel C, Wiedmann B, Bukau B, Ban N. A peptide deformylase-ribosome complex reveals mechanism of nascent chain processing. Nature. 2008 Mar 6;452(7183):108-11. Epub 2008 Feb 20. PMID:18288106 doi:10.1038/nature06683