4v6m
From Proteopedia
OCA (Talk | contribs)
(New page: ==Structure of the ribosome-SecYE complex in the membrane environment== <StructureSection load='4v6m' size='340' side='right' caption='4v6m, resolution 7.10Å' scen...)
Next diff →
Revision as of 07:13, 1 April 2015
proteopedia linkproteopedia linkStructure of the ribosome-SecYE complex in the membrane environment
Structural highlights
Disease[APOA1_HUMAN] Defects in APOA1 are a cause of high density lipoprotein deficiency type 2 (HDLD2) [MIM:604091]; also known as familial hypoalphalipoproteinemia (FHA). Inheritance is autosomal dominant.[1] [2] Defects in APOA1 are a cause of the low HDL levels observed in high density lipoprotein deficiency type 1 (HDLD1) [MIM:205400]; also known as analphalipoproteinemia or Tangier disease (TGD). HDLD1 is a recessive disorder characterized by the absence of plasma HDL, accumulation of cholesteryl esters, premature coronary artery disease, hepatosplenomegaly, recurrent peripheral neuropathy and progressive muscle wasting and weakness. In HDLD1 patients, ApoA-I fails to associate with HDL probably because of the faulty conversion of pro-ApoA-I molecules into mature chains, either due to a defect in the converting enzyme activity or a specific structural defect in Tangier ApoA-I.[3] [4] Note=A mutation in APOA1 is the cause of amyloid polyneuropathy-nephropathy Iowa type (AMYLIOWA); also known as amyloidosis van Allen type or familial amyloid polyneuropathy type III. AMYLIOWA is a hereditary generalized amyloidosis due to deposition of amyloid mainly constituted by apolipoprotein A1. The clinical picture is dominated by neuropathy in the early stages of the disease and nephropathy late in the course. Death is due in most cases to renal amyloidosis. Severe peptic ulcer disease can occurr in some and hearing loss is frequent. Cataracts is present in several, but vitreous opacities are not observed.[5] [6] [7] [8] Defects in APOA1 are a cause of amyloidosis type 8 (AMYL8) [MIM:105200]; also known as systemic non-neuropathic amyloidosis or Ostertag-type amyloidosis. AMYL8 is a hereditary generalized amyloidosis due to deposition of apolipoprotein A1, fibrinogen and lysozyme amyloids. Viscera are particularly affected. There is no involvement of the nervous system. Clinical features include renal amyloidosis resulting in nephrotic syndrome, arterial hypertension, hepatosplenomegaly, cholestasis, petechial skin rash.[9] [10] [11] Function[RL4_ECOLI] 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.[12] Protein L4 is a both a transcriptional repressor and a translational repressor protein; these two functions are independent of each other. It regulates transcription of the S10 operon (to which L4 belongs) by causing premature termination of transcription within the S10 leader; termination absolutely requires the NusA protein. L4 controls the translation of the S10 operon by binding to its mRNA. The regions of L4 that control regulation (residues 131-210) are different from those required for ribosome assembly (residues 89-103).[13] Forms part of the polypeptide exit tunnel.[14] Can regulate expression from Citrobacter freundii, Haemophilus influenzae, Morganella morganii, Salmonella typhimurium, Serratia marcescens, Vibrio cholerae and Yersinia enterocolitica (but not Pseudomonas aeruginosa) S10 leaders in vitro.[15] [RL3_ECOLI] One of two assembly inititator proteins, it binds directly near the 3'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit.[HAMAP-Rule:MF_01325_B] [RS17_ECOLI] One of the primary rRNA binding proteins, it binds specifically to the 5'-end of 16S ribosomal RNA. Also plays a role in translational accuracy; neamine-resistant ribosomes show reduced neamine-induced misreading in vitro.[HAMAP-Rule:MF_01345] [RS3_ECOLI] Binds the lower part of the 30S subunit head. Binds mRNA in the 70S ribosome, positioning it for translation (By similarity).[16] Plays a role in mRNA unwinding by the ribosome, possibly by forming part of a processivity clamp.[17] [RS15_ECOLI] 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.[HAMAP-Rule:MF_01343] In the E.coli 70S ribosome it has been modeled (PubMed:12809609) to contact the 23S rRNA of the 50S subunit forming part of bridge B4. In the two 3.5 A resolved ribosome structures (PubMed:16272117) there are minor differences between side-chain conformations.[HAMAP-Rule:MF_01343] [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] [RL1_ECOLI] One of the primary rRNA binding proteins, it binds very close to the 3'-end of the 23S rRNA. Forms part of the L1 stalk. It is often not seen in high-resolution crystal structures, but can be seen in cryo_EM and 3D reconstruction models. These indicate that the distal end of the stalk moves by approximately 20 angstroms (PubMed:12859903). This stalk movement is thought to be coupled to movement of deacylated tRNA into and out of the E site, and thus to participate in tRNA translocation (PubMed:12859903). Contacts the P and E site tRNAs.[HAMAP-Rule:MF_01318_B] Protein L1 is also a translational repressor protein, it controls the translation of the L11 operon by binding to its mRNA.[HAMAP-Rule:MF_01318_B] [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] [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] [Q0TCG1_ECOL5] The central subunit of the protein translocation channel SecYEG. Consists of two halves formed by TMs 1-5 and 6-10. These two domains form a lateral gate at the front which open onto the bilayer between TMs 2 and 7, and are clamped together by SecE at the back. The channel is closed by both a pore ring composed of hydrophobic SecY resides and a short helix (helix 2A) on the extracellular side of the membrane which forms a plug. The plug probably moves laterally to allow the channel to open. The ring and the pore may move independently (By similarity).[HAMAP-Rule:MF_01465][RuleBase:RU000537] [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] [RS10_ECOLI] Involved in the binding of tRNA to the ribosomes.[HAMAP-Rule:MF_00508] [RS16_ECOLI] In addition to being a ribosomal protein, S16 also has a cation-dependent endonuclease activity.[18] 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.[19] [RL24_ECOLI] 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. It is not thought to be involved in the functions of the mature 50S subunit in vitro.[20] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit.[21] [RS20_ECOLI] Binds directly to 16S ribosomal RNA.[HAMAP-Rule:MF_00500] [RS6_ECOLI] Binds together with S18 to 16S ribosomal RNA.[HAMAP-Rule:MF_00360] [RL2_ECOLI] One of the primary rRNA binding proteins. Located near the base of the L1 stalk, it is probably also mobile. 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 highly controversial.[HAMAP-Rule:MF_01320_B] In the E.coli 70S ribosome in the initiation state it has been modeled to make several contacts with the 16S rRNA (forming bridge B7b, PubMed:12809609); these contacts are broken in the model with bound EF-G.[HAMAP-Rule:MF_01320_B] [RL6_ECOLI] This protein binds directly to at least 2 domains of the 23S ribosomal RNA, thus 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.[HAMAP-Rule:MF_01365] Gentamicin-resistant mutations in this protein affect translation fidelity.[HAMAP-Rule:MF_01365] [RS7_ECOLI] 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, where it has been shown to contact mRNA. Has been shown to contact tRNA in both the P and E sites; it probably blocks exit of the E site tRNA.[22] Protein S7 is also a translational repressor protein; it regulates the expression of the str operon members to different degrees by binding to its mRNA.[23] [RL29_ECOLI] Binds 23S rRNA. It is not essential for growth.[HAMAP-Rule:MF_00374] One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit. Contacts trigger factor (PubMed:12226666).[HAMAP-Rule:MF_00374] [RL23_ECOLI] One of the early assembly proteins, it binds 23S rRNA; is essential for growth. One of the proteins that surround the polypeptide exit tunnel on the outside of the subunit. Acts as the docking site for trigger factor (PubMed:12226666) for Ffh binding to the ribosome (SRP54, PubMed:12756233 and PubMed:12702815) and to nascent polypeptide chains (PubMed:12756233).[HAMAP-Rule:MF_01369] [RL17_ECOLI] Requires L15 for assembly into the 50S subunit.[HAMAP-Rule:MF_01368] [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] [RL21_ECOLI] This protein binds to 23S rRNA in the presence of protein L20.[HAMAP-Rule:MF_01363] [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.[24] [RS19_ECOLI] In the E.coli 70S ribosome in the initiation state (PubMed:12809609) it has been modeled to contact the 23S rRNA of the 50S subunit forming part of bridge B1a; this bridge is broken in the model with bound EF-G. The 23S rRNA contact site in bridge B1a is modeled to differ in different ribosomal states (PubMed:12859903), contacting alternately S13 or S19. In the 3.5 angstroms resolved ribosome structures (PubMed:16272117) the contacts between L5, S13 and S19 bridge B1b are different, confirming the dynamic nature of this interaction. Bridge B1a is not visible in the crystallized ribosomes due to 23S rRNA disorder.[HAMAP-Rule:MF_00531] Protein S19 forms a complex with S13 that binds strongly to the 16S ribosomal RNA. Contacts the A site tRNA.[HAMAP-Rule:MF_00531] [Q0TA84_ECOL5] Essential subunit of the Sec protein translocation channel SecYEG. Clamps together the 2 halves of SecY. May contact the channel plug during translocation (By similarity).[HAMAP-Rule:MF_00422] [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] [RL14_ECOLI] This protein binds directly to 23S ribosomal RNA. In the E.coli 70S ribosome (PubMed:12809609) it has been modeled to make two contacts with the 16S rRNA of the 30S subunit, forming part of bridges B5 and B8, connecting the 2 subunits. Although the protein undergoes significant rotation during the transition from an initiation to and EF-G bound state, the bridges remain stable. In the 3.5 A resolved structures (PubMed:16272117) L14 and L19 interact and together make contact with the 16S rRNA in bridges B5 and B8.[25] Can also interact with RsfA, in this case bridge B8 probably cannot form, and the 30S and 50S ribosomal subunits do not associate, which represses translation.[26] [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] [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).[27] Located at the back of the 30S subunit body where it stabilizes the conformation of the head with respect to the body.[28] 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.[29] [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] [RS8_ECOLI] 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).[HAMAP-Rule:MF_01302_B] Protein S8 is a translational repressor protein, it controls the translation of the spc operon by binding to its mRNA.[HAMAP-Rule:MF_01302_B] [RL22_ECOLI] 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.[HAMAP-Rule:MF_01331_B] The globular domain of the protein is one of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit, while an extended beta-hairpin is found that penetrates into the center of the 70S ribosome where it lines the wall of the exit tunnel. Removal of most of this hairpin (residues 85-95) does not prevent its incorporation into 70S ribosomes. Two of the hairpin residues (91 and 93) seem to be involved in translation elongation arrest of the SecM protein, as their replacement by larger amino acids alleviates the arrest.[HAMAP-Rule:MF_01331_B] [RS11_ECOLI] 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).[HAMAP-Rule:MF_01310] [RS4_ECOLI] One of two assembly initiator proteins for the 30S subunit, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit.[30] [31] [32] With S5 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).[33] [34] [35] Plays a role in mRNA unwinding by the ribosome, possibly by forming part of a processivity clamp.[36] [37] [38] Protein S4 is also a translational repressor protein, it controls the translation of the alpha-operon (which codes for S13, S11, S4, RNA polymerase alpha subunit, and L17) by binding to its mRNA.[39] [40] [41] Also functions as a rho-dependent antiterminator of rRNA transcription, increasing the synthesis of rRNA under conditions of excess protein, allowing a more rapid return to homeostasis. Binds directly to RNA polymerase.[42] [43] [44] [RL13_ECOLI] 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.[HAMAP-Rule:MF_01366] [Q8X9Y5_ECO57] Essential cell division protein. May link together the upstream cell division proteins, which are predominantly cytoplasmic, with the downstream cell division proteins, which are predominantly periplasmic. May control correct divisome assembly (By similarity).[HAMAP-Rule:MF_00911] [RL5_ECOLI] 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. Its 5S rRNA binding is significantly enhanced in the presence of L18.[HAMAP-Rule:MF_01333_B] In the 70S ribosome in the initiation state (PubMed:12809609) was modeled to contact protein S13 of the 30S subunit (bridge B1b), connecting the 2 subunits; the protein-protein contacts between S13 and L5 in B1b change in the model with bound EF-G implicating this bridge in subunit movement (PubMed:12809609 and PubMed:18723842). In the two 3.5 A resolved ribosome structures (PubMed:16272117) the contacts between L5, S13 and S19 are different, confirming the dynamic nature of this interaction.[HAMAP-Rule:MF_01333_B] 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_B] [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] [RL11_ECOLI] This protein binds directly to 23S ribosomal RNA. Forms the L11 stalk, which is mobile in the ribosome, indicating its contribution to the activity of initiation, elongation and release factors.[HAMAP-Rule:MF_00736_B] [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.[45] [APOA1_HUMAN] Participates in the reverse transport of cholesterol from tissues to the liver for excretion by promoting cholesterol efflux from tissues and by acting as a cofactor for the lecithin cholesterol acyltransferase (LCAT). As part of the SPAP complex, activates spermatozoa motility.[46] Publication Abstract from PubMedThe ubiquitous SecY-Sec61 complex translocates nascent secretory proteins across cellular membranes and integrates membrane proteins into lipid bilayers. Several structures of mostly detergent-solubilized Sec complexes have been reported. Here we present a single-particle cryo-EM structure of the SecYEG complex in a membrane environment, bound to a translating ribosome, at subnanometer resolution. Using the SecYEG complex reconstituted in a so-called Nanodisc, we could trace the nascent polypeptide chain from the peptidyltransferase center into the membrane. The reconstruction allowed for the identification of ribosome-lipid interactions. The rRNA helix 59 (H59) directly contacts the lipid surface and appears to modulate the membrane in immediate vicinity to the proposed lateral gate of the protein-conducting channel (PCC). On the basis of our map and molecular dynamics simulations, we present a model of a signal anchor-gated PCC in the membrane. Cryo-EM structure of the ribosome-SecYE complex in the membrane environment.,Frauenfeld J, Gumbart J, Sluis EO, Funes S, Gartmann M, Beatrix B, Mielke T, Berninghausen O, Becker T, Schulten K, Beckmann R Nat Struct Mol Biol. 2011 May;18(5):614-21. Epub 2011 Apr 17. PMID:21499241[47] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||||
Categories: Escherichia coli | Escherichia coli 536 | Escherichia coli dh1 | Escherichia coli k-12 | Escherichia coli o157:h7 | Beatrix, B | Becker, T | Beckmann, R | Berninghausen, O | Frauenfeld, J | Funes, S | Gartmann, M | Gumbart, J | Mielke, T | Schulten, K | Sluis, E O.van der | 70s ribosome | Nanodisc | Nucleotide-binding | Protein biosynthesis | Ribonucleoprotein | Ribosomal protein | Ribosome | Ribosome-ribosomal protein complex | Secyeg | Translation | Translocon | Zinc-finger
