Halobacterium marismortui

Ribosomes from halophilic l cteria meet this requirement furthermore, the structure of a ribosome of an archaebaiterium (Halobacterium marismortui) as compared to that of a eubacterium (Bacillus stearothermophilus) might prove a valuable extension of our studies. 

Fig. 12. Views of flat (left) and perpendicular (right) glass spatulas constructed for crystallographic studies of plate-like crystals from Halobacterium marismortui 508 subunits at cryotemperature. The long c-axis (i.e. the shortest crystal dimension) will coincide with the spindle axis (and overlap problems will be less severe) when perpendicular spatulas are used...

Abbreviations Asa, Artemia salina Dme, Drosophila melanogaster Hsa, Homo sapiens Egr, Euglena gracilis, Ddi, Dictyostelium discoideum Sso, S. solfataricus Tee, Thermococcus celer Pwo, Pyrococcus woesei Mva, M. vannielii Hma, Halobacterium marismortui Tac, Thermoplasma acidophilum Tma, Thermotoga marilima Tth, Thermus thermophilus Eco, E. coli Mlu, Micrococcus luteus, Spl, Spirulina platensis Ech, E. gracilis chloroplast Smt, Saccharomyces cerevisiae mitochondria. 

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). 

Haloferax (formerly Halobacterium) volcanii, a moderately halophilic species. A close relative of Haloferax volcanii is Haloferax phenon K isolate Aa 2.2 [4]. Halobacterium marismortui, the subject of extensive work on ribosomal proteins, is not closely related to Halobacterium salinarium, instead, it belongs in the genus Haloarcula [2]. 

The number of rRNA operons in archaea is always small. Haloferax vol-canii, Methanobacterium thermoautotrophicum and Methanothermus fervidus have two, and Methanobacterium vannielii has four (reviewed by Brown et al. [5]). On the basis of Southern transfers of pulsed field gels, Sanz et al. [106] report that the halophilic archaea have from one to four rRNA operons Haloarcula californiae, 4 Haloferax gibbonsii, 4 Halobacterium halobium NCMB 111, 3 Halobacterium marismortui, 3 Halococcus morrhuae, 2 and Halobacterium salinarium, 1. Bacteria have from one to eleven copies (e.g.. Bacillus subtilis, 11 [107] Escherichia coli, 7 [108], and Mycoplasma pneumoniae, 1 [109]). In Halobacterium halobium, the presence of only one rRNA operon facilitated the isolation of strains with mutated 23S rRNA genes, which are resistant to thiostrepton [110], anisomycin [111] or chloramphenicol [112]. 

It was found for spontaneous crystal growth of ribosomal particles that the lower the Mg2+ concentration, the thicker the crystals (Arad, Leonard, Wittmann and Yonath 1984). Consequently, crystals from 50S subunits from Halobacterium marismortui, grown spontaneously under the lowest Mg2+ concentration possible, were transferred as seed crystals to solutions with even a lower Mg2+ concentration. As a result, after about two weeks, well-ordered and relatively thick crystals of about 0.6x0.6x0.2 mm were formed (figure 10.25) that diffracted to about 6 A (Makowski et al 1987). 

Malate dehydrogenase (Halobacterium marismortui) HalophUic malate dehydrogenase... 

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