The primary structure of protein L9 from the Escherichia coli ribosome

The use of Zwittergent 3-14 in the purification of recombinant human interferon-beta Ser17 (Betaseron)

A new method for purifying human interferon-beta SER17 from E. coli-derived inclusion bodies has been developed. This procedure eliminates the need for strong denaturants, such as sodium dodecyl sulfate or chaotropes. The procedure makes use of a nondenaturing detergent and a brief incubation at pH 12 to solubilize interferon-beta Ser17 from inclusion bodies. The detergent used was Zwittergent 3-14 (nonionic and pH-insensitive), which is included in the class of sulfobetaines (RN+ (CH3)2(CH2)xSO3-). Zwittergent 3-14 was used in combination with urea to produce a urea/Zwittergent 3-14 washed inclusion body preparation enriched in human interferon-beta Ser17 (Betaseron). Solubilization of inclusion bodies was accomplished by employing a brief (1 minute) shift to pH 12 in the presence of 2.5% Zwittergent 3-14 followed by rapid adjustment to pH 8.0. Solubilization was complete, and the solution could be rapidly adjusted to pH 8 without any observable precipitation of protein. The resultant supernatant could be successfully subjected to a number of chromatographic and analytic procedures, many of which are not compatible with strong anionic detergents, such as SDS. Betaseron was purified from Zwittergent 3-14 solubilized inclusion body lysates using both ion-exchange and size-exclusion chromatography. Purified Betaseron retained bioactivity and could be refolded by simple dialysis against a nonreducing buffer. This method represents a novel procedure for purifying Betaseron from inclusion bodies using a nondenaturing detergent and ion-exchange chromatography.

Structure of a cyanobacterial gene encoding the 50S ribosomal protein L9

The rplI gene encoding the ribosomal protein L9 was found 4 kbp downstream from the desA gene, but on the opposite strand, in the genome of the cyanobacterium Synechocystis PCC6803. The deduced amino acid sequence is homologous to the sequences of the L9 proteins from Escherichia coli and chloroplasts of Arabidopsis and pea. The gene is present as a single copy in the chromosome and is transcribed as a mRNA of 0.64 kb. An open reading frame of unknown function (ORF291) was found in the upstream region of the rplI gene.

Characterization of rps17, rp19 and rpl15: three nucleus-encoded plastid ribosomal protein genes

Approximately two-thirds of the 55 to 60 plastid ribosomal proteins are encoded in the nucleus. Since the protein products of each of these genes are needed in equal amounts for ribosome assembly, their expression may be coordinately regulated by common mechanisms. To begin to understand how the expression of these genes is regulated, we have isolated cDNA and genomic clones for three plastid ribosomal protein genes from an Arabidopsis thaliana library. The genes rps17, rpl9 and rpl15, encoding plastid ribosomal proteins CS17, CL9 and CL15, respectively, are located in the nuclear genome and Southern blot data suggest that each is a single copy gene in A. thaliana. Northern blot data show that transcripts from rps17, rpl9 and rpl15 are much more abundant in leaves and stems than they are in roots. The nucleotide sequences of each of these three genes were determined and their transcriptional initiation sites identified. rps17 transcripts have multiple 5' ends suggesting that they are initiated at multiple sites or are post-transcriptionally processed at their 5' end. rpl9 and rpl15 apparently have unique transcriptional initiation sites but are post-transcriptionally processed to remove six and three introns, respectively, from their primary transcripts. We have examined the genomic sequences for motifs that may be important for the proper expression of these genes. A 7 bp sequence motif, whose consensus is 5'-AGGCCCA-3', flanked by AT-rich regions was identified between 38 and 73 nucleotides upstream of the rps17, rpl9 and rpl15 transcriptional initiation sites.

The nucleotide sequence of an Escherichia coli chromosomal region containing the genes for ribosomal proteins S6, S18, L9 and an open reading frame

The DNA sequence of a cluster of genes for ribosomal proteins S6 (rpsF), S18 (rpsR) and L9 (rplI), and of their surrounding regions was determined. The order of the genes was established as promoter-rpsF-rpsR-rplI. There is a 315 bp open reading frame that begins seven nucleotides after the end of rpsF and ends immediately before rpsR. Based on the data of insertional mutagenesis experiments with transposon gamma delta, we concluded that these genes probably form an operon. The amino acid sequence deduced from the nucleotide sequence of the genes agrees completely with the published amino acid sequence data for protein S6, but there are discrepancies in the case of proteins S18 and L9. The C-terminus of protein S6 was deduced to end with two Glu residues, suggesting that the other Glu residues previously found in this protein are added post-translationally as has been predicted (Reeh and Pedersen 1979). A possible secondary structure in the leader sequence as well as a possible transcriptional terminator after rplI were noticed in the sequence.

The complete amino acid sequences of ribosomal proteins L17, L27, and S9 from Bacillus stearothermophilus

The complete primary structures of proteins L17, L27 and S9 extracted from the Bacillus stearothermophilus ribosomes with 1 M NaCl and purified to homogeneity by column chromatography have been determined. The amino acid sequences of these proteins are compared to those of the homologous ribosomal proteins from Escherichia coli. The number of identical amino acid residues between the homologous proteins lies between 33-55%.

The structural periodicity of E. coli ribosomal proteins

It is established that the sequences of all different proteins from E. coli ribosome as well as two protein biosynthesis initiation factors, two ribosome-associated DNA-binding proteins, and the elongation factor EF-Tu from the same source possess a periodicity expressed more weakly and different from that found earlier for a number of proteins representatives of 18 superfamilies. The statistical significance of the periodicity observed was checked by comparing the area below the periodicity curve of every protein examined with that of computer generated sequences having the same amino acid composition and length. The results concerning the proteins from small and large ribosomal subunit are compared. The conclusions support and supplement the concept about the presence of a trend in protein molecular evolution from universal (Gly, Ala) to specialized (Phe, Tyr, Trp, Cys) amino acids.

Reversed-phase liquid chromatography of peptides for direct micro-sequencing

Tryptic and cyanogen bromide peptides derived from yeast aspartyl-tRNA synthetase and from Escherichia coli ribosomal proteins were separated by reversed-phase liquid chromatography, employing volatile buffers of low ionic strength. The conditions used allow the performance of micro-sequencing without desalting or extensive lyophilization, and can therefore be applied to peptide mixtures containing hydrophobic fragments which tend to precipitate. To prevent losses of peptides, direct ultra-violet detection of the peptides was preferred, to detection by post-column derivatization with an additional stream splitting device. Preparative separations were performed with 5-10 nmol of peptide mixture; analytical runs were made with 5-10 micrograms of protein hydrolysate.