Purification and characterization of ribosomal proteins from the 30 S subunit of the extreme halophile Halobacterium marismortui

Purification and characterization of a histone-like protein from the Archaeal isolate AN1, a member of the Thermococcales

We have purified and characterized the histone-like protein, termed HAN1, and an HAN1-associated DNA-binding protein (hDBP) from nucleoids of the hyperthermophilic Thermococcus-like AN1. HAN1 is shown to be composed of two subunits, to be thermally stable and to compact DNA in a reversible manner. The N-terminal sequence of HAN1 shares a high degree of homology with HMf, the histone-like protein from Methanothermus fervidus. Consistent with this, the toroidal wrapping of DNA by HAN1 resembles that described for HMf. However, significant differences in both twist and writhe components of these complexes are indicated by the 12.0 bp helical repeat produced during hydroxyl radical footprinting with HAN1. Furthermore, the increased stability of HAN1: DNA complexes allows DNA to be protected from thermal denaturation and cleavage by the restriction enzyme TaqI at 65 degrees C. The hDBP, which co-purified with HAN1,is shown to represent a major portion of the acid-washed nucleoid protein in AN1 and to enhance the mobility of DNA directly, yet decrease the mobility of HAN1:DNA complexes.

Cartography of ribosomal proteins of the 30S subunit from the halophilic Haloarcula marismortui and complete sequence analysis of protein HS26

By two-dimensional polyacrylamide gel electrophoresis of 30S ribosomal subunit proteins (S proteins) from Haloarcula marismortui we identified 27 distinct spots and analyzed all of them by protein sequence analysis. We demonstrated that protein HmaS2 (HS2) is encoded by the open reading frame orfMSG and has sequence similarities to the S2 ribosomal protein family. The proteins HmaS5 and HmaS14 were identified as spots HS7 and HS21/HS22, respectively. Protein HS4 was characterized by amino-terminal sequence analysis. The spot HS25 was recognized as an individual protein and also characterized by sequence analysis. Furthermore, the complete primary sequence of HS26 is reported, showing similarity only to eukaryotic ribosomal proteins. The sequence data of a further basic protein shows a high degree of similarity to ribosomal protein S12, therefore, it was designated HmaS12. Slightly different results compared to published sequence data were obtained for the protein HS12 and HmaS19. The putative 'ribosomal' protein HSH could not be localized in the two-dimensional pattern of the total 30S ribosomal subunit proteins of H. marismortui. Therefore, it seems to be unlikely that this protein is a real constituent of the H. marismortui ribosome.

Nucleotide sequence of the genes for ribosomal proteins HS15 and HSH from Haloarcula marismortui: an archaeon-specific gene cluster

The nucleotide sequences of the genes for two ribosomal proteins, HS15 and HSH, from the archaeon Haloarcula marismortui, have been determined. The genes were found in a cluster together with another open reading frame with a probable regulatory function. HS15 and HSH have counterparts in eucarya. HS15 is significantly homologous to S19 from frog (Xenopus laevis). HSH is related to S37 from yeast (Saccharomyces cerevisiae) and S27 from fly (Drosophila melanogaster), as well as to other members of the S27 family. Eubacterial counterparts were not found, suggesting that these proteins are 'extra proteins' that are absent in eubacterial ribosomes.

Crystallization of halophilic malate dehydrogenase from Halobacterium marismortui

Malate dehydrogenase from the extreme halophile Halobacterium marismortui crystallizes in highly concentrated phosphate solution in space group 12 with cell dimensions a = 113.8 A, b = 122.8 A, c = 126.7 A, beta = 98.1 degrees. The halophilic enzyme was found to be unstable at lower concentrations of phosphate. It associates with unusually large amounts of water and salt, and the combined particle volume shows a tight fit in the unit cell.

Complete amino acid sequences of the ribosomal proteins L25, L29 and L31 from the archaebacterium Halobacterium marismortui

Ribosomal proteins were extracted from 50S ribosomal subunits of the archaebacterium Halobacterium marismortui by decreasing the concentration of Mg2+ and K+, and the proteins were separated and purified by ion-exchange column chromatography on DEAE-cellulose. Ten proteins were purified to homogeneity and three of these proteins were subjected to sequence analysis. The complete amino acid sequences of the ribosomal proteins L25, L29 and L31 were established by analyses of the peptides obtained by enzymatic digestion with trypsin, Staphylococcus aureus protease, chymotrypsin and lysylendopeptidase. Proteins L25, L29 and L31 consist of 84, 115 and 95 amino acid residues with the molecular masses of 9472 Da, 12293 Da and 10418 Da respectively. A comparison of their sequences with those of other large-ribosomal-subunit proteins from other organisms revealed that protein L25 from H. marismortui is homologous to protein L23 from Escherichia coli (34.6%), Bacillus stearothermophilus (41.8%), and tobacco chloroplasts (16.3%) as well as to protein L25 from yeast (38.0%). Proteins L29 and L31 do not appear to be homologous to any other ribosomal proteins whose structures are so far known.