Halobacterium cutirubrum ribosomes. Properties of the ribosomal proteins and ribonucleic acid

Abstract

1. The 30S ribosomal subunit of the extreme halophile Halobacterium cutirubrum is unstable and loses 75% of its ribosomal protein when the 70S ribosome is dissociated into the two subunits. A stable 30S subunit is obtained if the dissociation of the 70S particle is carried out in the presence of the soluble fraction. 2. A fractionation procedure was developed for the selective removal of groups of proteins from the 30S and 50S subunits. When the ribosomes, which are stable in 4m-K(+) and 0.1m-Mg(2+), were extracted with low-ionic-strength buffer 75-80% of the 30S proteins and 60-65% of the 50S proteins as well as the 5S rRNA were released. The proteins in this fraction are the most acidic of the H. cutirubrum ribosomal proteins. Further extraction with Li(+)-EDTA releases additional protein, leaving a core particle containing either 16S rRNA or 23S rRNA and about 5% of the total ribosomal protein. The amino acid composition, mobility on polyacrylamide gels at pH4.5 and 8.7, and the molecular-weight distribution of the various protein fractions were determined. 3. The s values of the rRNA are 5S, 16S and 23S. The C+G contents of the 16S and 23S rRNA were 56.1 and 58.8% respectively and these are higher than C+G contents of the corresponding Escherichia coli rRNA (53.8 and 54.1%).

[FeFe] Hydrogenase Genetic Diversity Provides Insight into Molecular Adaptation in a Saline Microbial Mat Community

“…These observations are consistent with the results of previous investigations of deduced amino acid sequences from a variety of halophilic organisms that indicate hydrophobicity indices lower than those of their nonhalophilic counterparts, which is hypothesized to reduce the effects of salt-driven protein misfolding and/or aggregation (11,12,14,24,27,31). In addition, many of the putative HydA sequences recovered from GN exhibited previously unobserved substitutions in the L1 motif and novel insertion domains upstream from the L1 motif (Fig.…”

An acidic, alanine‐rich 50 S ribosomal protein from Halobacterium cutirubrum: Amino acid sequence homology with Escherichia coli proteins L7 and L12

“…The ribosomes were isolated from H. cutirubrum cells grown at 42°C [3]. Fractionation of the ribosoma1 proteins was by DEAE-cellulose column chromatography [S] , with the isolated H. cutirubrum L20 being identified by two-dimensional electrophoresis [2] and amino acid composition [5].…”

“…of NaCl for growth [l] , and its ribosomal proteins are largely acidic, unlike those for other cell types [3,4]. Despite these physiological differences and apparent structural dichotomies, the fact that regions of E. coli and their corresponding region of H. cutirubrum L20 are highly conserved during the evolution of these dinstinct procaryotic cell types suggest these portions of these molecules must have some real importance in protein synthesis.…”

The complete amino acid sequence of ribosomal protein H‐S11 from the archaebacterium Halobacterium marismortui

“…Halophiles are well characterized archaebacteria with regard to ribosomal structure. A striking feature of the halobacterial ribosomes is that unlike all other organisms, most of their ribosomal proteins are acidic [2]. Furthermore, the ribosomes of halobacteria share eubacterial as well as eukaryotic features.…”