Tetrahymena thermophila

Tetrahymena thermophila transforms pentachloronitrobenzene to the corresponding aniline and pentachlorothioanisole (Figure 2.24) (Murphy et al. 1982). 

Drotar A-M, LR Fall, EA Mishalanie, JE Tavernier, R Eall (1987) Enzymatic methylation of sulfide, selenide, and organic thiols by Tetrahymena thermophila. Appl Environ Microbiol 53 2111-2118. 

All four scientists whose work led to modification of the dogmas received the Nobel Prize. Thomas Cech (1987) was the first to observe enzyme-like reactions taking place at the same RNA strand, in ribosomal RNA (rRNA) from the proto-zoon Tetrahymena thermophila. The RNA produced, which is completely viable, is formed in a process in which certain sections (introns) of the primary copy (the transcription of DNA to mRNA) are cut out, the two remaining ends of the exon then being rejoined (spliced). 

Stargell LA, Bowen J, Dadd CA, Dedon PC, Davis M, Cook RG, Allis CD, Gorovsky MA (1993) Temporal and spatial association of histone H2A variant hvl with transcriptionally competent chromatin during nuclear development in Tetrahymena thermophila. Genes Dev 7 2641-2651... 

Group I intron phosphotransesterification reactions are carried out by a conserved active site that contains a set of imperfect double helices named PI through P9. (See Figure 6.4.) P1-P9 helices are organized into three domains P1-P2, P4-P6, and P3-P9. Specifically, the Tetrahymena thermophila intron contains two sets of coaxially stacked helices that overlap to create the active site. These helices reside in two domains of approximately equal size P4-P6 and P3-P9. P domains are defined as base-paired regions, whereas J domains... 

The Cech group described an X-ray crystallographic structure of the group I intron from Tetrahymem thermophila in a Science magazine research article published in 1998 (PDB IGRZ). The 5.0-A resolution crystal structure included 247 nucleotides comprising most of the Tetrahymena thermophila intron. At this resolution, clear density for the ribozyme backbone was seen, and stacked bases were visualized as continuous tubes of electron density. 

The Lester and Dougherty labs, which have collaborated to extend the suppression mutagenesis technique to Xenopus oocytes with remarkable success [30, 31], began with a suppressor tRNA ( MN3 ) designed for in vivo use and demonstrated that it functioned more effectively in the oocyte system than a yeast tRNA -derived suppressor tRNA. They have since developed an alternative suppressor based on tRNA " from Tetrahymena thermophila that has proven to be considerably more versatile, efficient and accurate in the oocyte system [32], as well as showing good suppression efficiency in E. coli transcription-translation reactions [33]. 

Fig. 2. The P4-P6-domain of the group I intron of Tetrahymena thermophila. A Schematic representation of the secondary structure of the whole self-cleaving intron (modified after Cate et al. [34]). The labels for the paired regions P4 to P6 are indicated. The grey shaded region indicate the phylogenetically conserved catalytic core. The portion of the ribozyme that was crystallized is framed. B Three dimensional structure of the P4-P6 domain. Helices of the PSabc extension are packed against helices of the conserved core due to a bend of approximately 150° at one end of the molecule...

Allis, C.D., Glover, C.V.C., Bowen, J.K., and Gorovsky, M.A. (1980) Histone variants specific to the transcriptionally active amitotically dividing macronucleus of the unicellular eukaryote, Tetrahymena thermophila. Cell 20, 609-617. 

Yu, L. and Gorovsky, M.A. (1997) Constitutive expression, not a particular primary sequence, is the important feature of the H3 replacement variant hv2 in Tetrahymena thermophila. Mol. Cell. 

H2A.1, H2A.2, and H2A.X are phosphorylated at serine residue 1 [8,9]. H2A.Z is not phosphorylated. In vitro protein kinase C phosphorylates H2A at serine residue 1 [10]. Telrahymena H2A is phosphorylated in the C-terminal sequence [11]. Tetrahymena H2A.1 is phosphorylated at serine residues 122, 124, and 129, while H2A.2 is modified at serine residues 122 and 128 (Fig. 3). Phosphorylation of H2A occurs in the transcriptionally active macronucleus of Tetrahymena thermophila, but not in the transcriptionally inert micronucleus [12]. Tetrahymena H2A variant hvl is phosphorylated [13]. H4, like H2A, is phosphorylated at N-terminal serine... 

The microbiotest with ciliate protozoan Tetrahymena thermophila (Protoxkit E , which only became available commercially recently) evaluates the growth inhibition of the uniceUulars submitted for 20 hours to a toxicant [100]. The decreased multiplication of the ciliates is determined indirectly via the reduction in their food uptake, by optical density measurement in 1 cm spectrophotometric cells. 

Figure 2.1 Structures of histone acetyltransferases (HATs). Ribbon representation of the structures of the HAT domains of (a) Tetrahymena thermophila CcnS (PDBcode Iqsr), (b) Saccharomyces cerevisiae Hatl (PDB code Ibob), (c) S. cerevisiae Esal (PDB code Imja),...

Several other processes were investigated and developed as well, e.g., a) Am-bruticin S production in airlift and stirred tank reactor b) high-cell density cultivation of E. coli and production of rDNA products c) production of thermostable xylanase by Thermomyces lanuginosus d) cultivation of Tetrahymena thermophila in 1.5 bioreactors, e) alginate production by Azotobacter vine-landii. 

ID 1MME3. Ribozymes, or RNA enzymes, catalyze a variety of reactions, primarily in RNA metabolism and protein synthesis The complex three-dimensional structures of these RNAs reflect the complexity inherent in catalysis, as described for protein enzymes in Chapter 6. (c) A segment of mRNA known as an intron, from the ciliated protozoan Tetrahymena thermophila (derived from PDB ID 1GRZ). This intron (a ribozyme) catalyzes its own excision from between exons in an mRNA strand (discussed in Chapter 26). 

Table 2.1. Sequence context of mutation types and their frequencies observed after application of error-prone PCR as described herein and sequencing of cloned genes. Targets T7 RNAP, coding sequence of T7 RNA polymerase, Poll, coding sequence of E. coli DNA polymerase I, Inti on, cDNA of Tetrahymena thermophila intron,...

Lavine JE, Cantlay E, Roberts C et al (1982) Purification and properties of galactokinase from Tetrahymena thermophila. Biochim Biophys Acta 717 76-85... 

Gilron, G.L., Gransden, S.G., Lynn, D.H., Broadfoot, J. and Scroggins, R. (1999) A behavioral toxicity test using the ciliated protozoan Tetrahymena thermophila. I. Method description, Environmental Toxicology and Chemistry 18 (8), 1813-1816. 

Lehnert, V., Jaeger, L., Michele, F., and Westhof, E. (1996). New loop-loop tertiary interactions in self-splicing introns of subgroup IC and ID A complete 3D model of the Tetrahymena thermophila ribozyme. Chem. Biol. 3, 993—1009. 

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