Haloarcula marismortui, ribosomal subunit structure

Figure 29-6 Some protein-RNA interactions within the ribosome. (A) A space-filling model of the 23S and 5S RNA with associated proteins from the ribosome of Haloarcula marismortui. The CCA ends of bound tRNA molecules in the A, P, and E sites are also included. The view is looking into the active site cleft. The proteins with e after the number are related to eukaryotic ribosomal proteins more closely than to those of E. coli.17 Courtesy of T. A. Steitz. (B) Three-dimensional structure of a 70S ribosome from Thermus thermophilus. The 30S subunit is to the right of the 50S subunit. Courtesy of Yusupov et al.33a (C) Stereoscopic view of the helix 21 to helix 23b region of the 16S RNA with associated proteins S6 (upper left), S18 (upper center, front), and S15 (lower back) from T. thermophilus. Courtesy of Agalarov et at.31 (D) Simplified in vitro assembly map of the central domain of the 30S bacterial ribosome. Courtesy of Gloria Culver. (E) Contacts of proteins with the central (platform) domain of the 16S RNA component. The sequence shown is that of Thermus thermophilus. Courtesy of Agalarov et al. (F) Three drawings showing alternative location of the four copies of protein L7/L12. The N-terminal and C-terminal...

However, the exact number of proteins present in the archaeal ribosome is still unknown. The number quoted by various investigators, based on 2D polyacrylamide gel electrophoresis, depends on the resolving power of the gel system used. Recent studies by Casiano et al. [11] suggest that the Sulfolobus 508 ribosomal subunit could contain as many as 43 r-proteins, and work from our laboratory [12] on the structure of the Sulfolobus r-proteins and from Wittmann s laboratory [13] on Haloarcula (formerly Halobacterium) marismortui r-proteins indicates an increasing number of proteins present in the archaeal ribosome that are not present in the bacterial ribosome. It may well be that the archaeal ribosome contains more proteins than are present in the bacterial E. coll) ribosome, or the bacterial ribosome contains proteins not found in the archaeal ribosome (see section 6). 

Figure 29-4 Structure of 23S-28S ribosomal RNAs. (A) The three-dimensional structure of RNA from the SOS subunit of ribosomes of Haloarcula marismortui. Both the 5S RNA and the six structural domains of the 23S RNA are labeled. Also shown is the backbone structure of protein LI. From Ban rf Courtesy of Thomas A. Steitz. (B) The corresponding structure of...

Figure 29-4 Structure of 23S-28S ribosomal RNAs. (A) The three-dimensional structure of RNA from the SOS subunit of ribosomes of Haloarcula marismortui. Both the 5S RNA and the six structural domains of the 23S RNA are labeled. Also shown is the backbone structure of protein LI. From Ban cf Courtesy of Thomas A. Steitz. (B) The corresponding structure of the 23S RNA from Thermus thermophilus. Courtesy of Yusupov et alP (C) Simplified drawing of the secondary structure of . coli 23S RNA showing the six domains. The peptidyltransferase loop (see also Fig. 29-14) is labeled. This diagram is customarily presented in two halves, which are here connected by dashed lines. Stem-loop 1, which contains both residues 1 and 2000, is often shown in both halves but here only once. From Merryman et al7 Similar diagrams for Haloarcula marismortui and for the mouse reveal a largely conserved structure with nearly identical active sites. (D) Cryo-electron microscopic (Cryo-EM) reconstruction of a SOS subunit of a modified E. coli ribosome. The RNA has been modified genetically to have an...

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