The genes corresponding to the L10 and L12 equivalent ribosomal proteins (L10e and L12e) of Escherichia coli have been cloned and sequenced from two widely divergent species of archaebacteria, Halobacterium cutirubrum and Sulfolobus solfataricus. The deduced amino acid sequences of the L10e and L12e proteins have been compared to each other and to available eubacterial and eucaryotic sequences. We have identified the human P0 protein as the eucaryotic L10e. The L10e proteins from the three kingdoms were found to be colinear. The eubacterial L10e protein is much shorter than the archaebacterial-eucaryotic proteins because of two large deletions, one internal and one at the carboxy terminus. The archaebacterial and eucaryotic L12e proteins were also colinear; the eubacterial protein is homologous to the archaebacterial and eucaryotic L12e proteins, but has suffered rearrangement through what appear to be gene fusion events. Intraspecies comparisons between L10e and L12e sequences indicate the archaebacterial and eucaryotic L10e proteins contain a partial copy of the L12e protein fused to their carboxy terminus. In the eubacteria most of this fusion has been removed by the carboxy terminal deletion. Within the L12e-derived region, a 26-amino acid-long internal modular sequence reiterated thrice in the archaebacterial L10e, twice in the eucaryotic L10e, and once in the eubacterial L10e was discovered. This modular sequence also appears to be present as a single copy in all L12e proteins and may play a role in L12e dimerization, L10e-L12e complex formation, and the function of L10e-L12e complex in translation.(ABSTRACT TRUNCATED AT 250 WORDS)
An unidentified halophile isolated from plates of a complex agar medium containing 4.25 M NaCl showed optimum growth in broths containing 0.5-1.0 M NaCl but exhibited a wide range of growth from 0.045-4.5 M. The organism can be classified as a facultative halophile with wide salt tolerance. Logarithmic phase cells grown in media containing 0.5 M NaCl were rod-shaped in long chains which changed to smaller, single, or paired cells in stationary growth. The internal Na+ and K+ concentrations were 0.05 M and 0.34 M for logarithmic phase cells and 0.29 and 0.32 M for stationary phase cells. In 4.3 M NaCl media the cells were rod-shaped throughout the growth cycle, occurring primarily in pairs. The internal Na+ K" concentrations in cells in logarithmic phase growth were 0.62 M and 0.58 M while in stationary phase growth these values were 1.01 M and 0.66 M respectively. In contrast, logarithmic phase cells of the extreme halophile Halobacterium cutirubrum had internal Na+ and K+ concentrations of 0.80 M and 5.32 M when grown in 3.3 M NaCl. The internal Na+ and K+ concentrations, therefore, in the unidentified halophile do not resemble those found in H. cutirubrum but are much closer to those present in Escherichia coli.
An antibody specific for ribulose 1 ,5-dipliospliate carboxylase was used to isolate the enzyme from greening barley (Hordeum vulgare L.) leaves. Th-e increase in enzymatic activity during greening was due to de novo synthesis of the enzyme. Increases in enzymatic activ-ity were acconmpanied by corresponding increases in enzyme proteini and by incorporation of radioactive leucine, all of whlich were inhiibited by low concentrations of cyclolheximide. "-C-Labeled amino acids were incorporated into the enzyme by covalent peptide bon-ding.
The intracellular potassium concentration and percentage of acidic ribosomal proteins were determined for nine methanogenic bacteria representing diverse phylogenetic groupings. Representatives of the Methanobacteriaceae family possessed very high internal potassium concentrations: Methanobrevibacter arboriphilus, 1225 mM; Methanobrevibacter smithii, 1065 mM; Methanobacterium thermoautotrophicum, 1103 mM; Methanobacterium bryantii, 861 mM; and Methanobacterium strain G2R, 886 mM. Members of other families tested maintained much lower internal concentrations of potassium. Methanosarcina barkeri (family Methanosarcinaceae) and Methanospirillum hungatei (family Methanomicrobiaceae) maintained approximately 200 mM internal potassium, while Methanococcus voltae (family Methanococcaceae) possessed an intermediate concentration of 725 mM. Those organisms maintaining the highest internal potassium concentrations also had the largest number of acidic ribosomal proteins. There appeared to be a correlation among the phylogenetic placement of the organism (based on 16S rRNA sequence data), its content of intracellular potassium, and the percentage of acidic ribosomal proteins. Those methanogens most closely related to extreme halophiles possessed the highest concentrations of internal potassium and had an increased percentage of acidic ribosomal proteins, both properties of halophilic bacteria.
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