Genetic studies of the ribosomal proteins in Escherichia coli. 8. Mapping of ribosomal protein components by intergeneric mating experiments between Serratia marcescens and Escherichia coli

Isolation and molecular characterization of the ribosomal protein L6 homolog from Chlamydia trachomatis

The cloning of a Chlamydia trachomatis eukaryotic cell-binding protein reported earlier from our laboratory (R. Kaul, K. L. Roy, and W. M. Wenman, J. Bacteriol. 169:5152-5156, 1987) represents an artifact generated by nonspecific recombination of chromosomal DNA fragments. However, the amino terminus of this plasmid-encoded fusion product demonstrated significant homology to Escherichia coli ribosomal protein L6. By using a 458-bp PstI-HindIII fragment of recombinant pCT161/18 (representing the 5' end of the cloned gene), we isolated and characterized a C. trachomatis homolog of the ribosomal protein L6 gene of E. coli. Sequence analysis of an 1,194-bp EcoRI-SacI fragment that encodes chlamydial L6 (designated CtaL6e) revealed a 552-bp open reading frame comprising 183 amino acids and encodes a protein with a molecular weight of 19,839. Interestingly, complete gene homology between C. trachomatis serovars L2 and J, each of which exists as a single copy per genome, was observed. Expression of a plasmid-encoded gene product is dependent on the lac promoter, since no product was obtained if the open reading frame was oriented in opposition to the lac promoter. Immunoblotting of purified ribosomes revealed functional, as well as antigenic, homology between the E. coli and C. trachomatis ribosomal L6 proteins.

Cloning and DNA sequence determination of the L11 ribosomal protein operon of Serratia marcescens and Proteus vulgaris: translational feedback regulation of the Escherichia coli L11 operon by heterologous L1 proteins

In Escherichia coli the genes encoding ribosomal proteins L11 (rplK) and L1 (rplA) are contained in a single operon and their expression is translationally regulated by L1. We have cloned the homologous genes from two other enterobacteria, Serratia marcescens and Proteus vulgaris, and determined nucleotide sequences. The genes are organized in a similar way to that found in E. coli. Conservation of nucleotide and amino acid sequences relative to E. coli in the protein coding regions are 89.2% and 94.7% for S. marcescens, and 80.9% and 88.6% for P. vulgaris. Nucleotide sequences of L11 mRNA leader regions were strongly conserved for the primary as well as the secondary structures in the L1 target site. We have also constructed plasmids carrying E. coli L11 and either P. vulgaris or S. marcescens L1 genes fused to the lac promoter, with or without the E. coli leader containing the L1 target site. Induction of transcription of the operons possessing the E. coli mRNA leader did not lead to overproduction of L11, indicating translational regulation of the chimeric operon as well as the chromosomal operon by the plasmid encoded L1. Repression of the chromosomal L11 operon was directly demonstrated upon induction of the chimeric operons without the leader, which also lack the L11 initiation signal but have a mutation allowing L1 translation.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of a Serratia marcescens mutant which is an efficient recipient for the E. coli episome

A Serratia marcescens mutant, which is an efficient recipient for the Escherichia coli episome (F' plasmid), was isolated after mutagenesis by N-methyl-N'-nitro-N-nitrosoguanidine (NTG). Episomes could be maintained in the mutant cell under conditions selective for a gene on the plasmid. This S. marcescens mutant could also be transformed with pBR 322 DNA at a frequency higher than that of the parental strain.

Genetic studies of the ribosomal proteins in Escherichia coli. X. Mapping of the ribosomal proteins, L21 and S15, by intergeneric mating experiments between Serratia marcescens and Escherichia coli K12

Episomes of E. coli, which cover argG but not the str region, were transferred to Serratia marcescens. Ribosomal proteins from these hybrid strains were analyzed with phospho-cellulose or carboxy-methyl-cellulose column chromatography. Two E. coli ribosomal proteins, L21 and S15, could be detected in the ribosome from the hybrid strains in addition to the ribosomal proteins of S. marcescens.

Genetic studies of the ribosomal proteins in Escherichia coli. IX. Mapping of the ribosomal proteins, S2 and S20, by intergeneric mating experiments between Serratia marcescens and Escherichia coli K12

Episomes of E. coli K12, which cover thrleu region of the chromosome, were transferred to Serratia marcescens. Ribosomal proteins from these hybrid strains were analyzed with phosphocellulose column chromatography. Two E. coli 30S ribosomal proteins, S2 and S20, could be detected in the ribosome of the hybrid strain in addition to all ribosomal proteins of S. marcescens.

Study on proteins from yeast cytoplasmic ribosomes by two-dimensional gel electrophoresis

Proteins of yeast cytoplasmic ribosomes were analyzed by two different methods of two dimensional gel electrophoresis: run at pH 8.6 in 1-D1 and at pH 4.6 in 2-D (Method A); run at pH 5.0 in 1-D and in the presence of sodium dodecyl sulfate in 2-D (Method B). The numbers of proteins estimated were 28 (Method A) and 29 or 30 (Method B) in the 40S small subunit, and 40 (Method A) and 41 (Method B) in the 60S large subunit, respectively. Molecular weights of proteins in the small and the large subunits were found to be less than 40,000 and 60,000 respectively.

Correlation of 30S ribosomal proteins of Escherichia coli fractionated on carboxymethyl-cellulose column chromatography to the standard nomenclature

The nomenclature proposed by Otaka et al. (1968) for the 30S ribosomal protein components of Escherichia coli as separated by carboxymethyl(CM)-cellulose column chromatography was adopted in several papers in which the genetic loci for many 30S ribosomal proteins on the E. coli chromosome were determined. In order to compare these data with those obtained in other laboratories, the 30S ribosomal proteins fractionated by CM-cellulose chromatography were correlated with thestandard nomenclature proposed by Wittmann et al. (1971).

Expression of ribosomal protein genes in Escherichia coli

Streptomycin or spectinomycin treatment of an E. coli strain, carrying the strR and spcR alleles on the chromosome and the wild-type (sensitive) alleles on the episome, selects for inactivation of the relevant sensitive allele. After Mu induced mutagenesis, in the absence of selection against extended deletions upon the episome, a large proportion of stro mutants are also spco, and vice versa. However, when markers flanking the strA and spcA gene cluster are simultaneously selected, effectively eliminating long deletions, the majority of stro mutants continue to express the spcs allele, and vice versa. Insofar as inactivation after Mu treatment is due to prophage insertion within or proximal to the genes in question, this result indicates that the genes strA and spcA are not parts of a single operon. In virtue of the high frequency of extended deletions observed in the absence of suitable counter-selection, we must place a word of caution upon the use of phage Mu-1 as a means of isolating polar mutations and defining transcriptional units.

Specialized transducing phages for ribosomal protein genes of Escherichia coli

Specialized lambda transducing phages have been isolated carrying approximately half the ribosomal protein genes of E. coli. These phages carry regions of the bacterial chromosome between aroE and fus. The ribosomal protein genes on these phages have been identified by the stimulation of ribosomal protein synthesis in ultraviolet-irradiated bacteria following infection by the transducing phage, and by the in vitro synthesis of ribosomal proteins in a DNA-dependent protein synthesizing system. The results indicate lambdadspcl probably carries at least 22 ribosomal protein genes and lambdadspc2 at least 26 genes. All these genes are clustered between trkA and strA. At least 13 of them have not been previously mapped.

Genetic analysis of cold-sensitive ribosome maturation mutants of Escherichia coli

Four cold-sensitive mutants of Escherichia coli, which have defects in the maturation of the 50S ribosomal subunit, were isolated. Each of the mutations was shown to map at a different locus. The loci were assigned the name rim (ribosome maturation) and were shown to map as follows: rimA is co-transduced with ilvD and with pyrE; rimB is co-transduced with aroD; conjugation experiments limited rimD to a region between ilv and malB, and conjugation experiments limited rimC to the 22 to 30 min region of the chromosome. In merodiploids heterozygous for rimA, rimB, or rimD, the wild-type allele was shown to be dominant to the mutant allele. The observation that the rim loci lie outside the strA region and separate from each other, as well as the recessive character of the rim loci, suggests that the mutants may be defective in ribosome maturation factors rather than being defective in ribosomal structural proteins.

Review lecture on the growth and form of a bacterial cell

The size, shape and composition of cells in cultures of bacteria maintained in steady states of exponential growth depend on the cultural conditions employed. Important factors influencing these parameters are the growth rate of the culture and the transit time of replication forks from one end of a chromosome to the other. The considerable progress which has been made in the last ten years in elucidating the rules governing the form and composition of cells of Escherichia coli as a function of growth rate and transit time is outlined in the Review.