Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vitro synthesis of elongation factor (EF)-Tu (tufB), the beta beta' subunits of RNA polymerase, ribosomal proteins L10 and L12 directed by DNA from the transducing phage lambda rifd 18, EF-Tu (tufA), EF-G, and the alpha subunit of RNA polymerase directed by DNA from the transducing phage lambda fus3 has been investigated in a crude and a partially defined protein-synthesizing system. Proteins L10 and L12 are synthesized in the partially defined system almost as well as in the crude system. However, the synthesis of EF-Tu, EF-G, and the alpha and beta beta' subunits of RNA polymerase is far less efficient in the partially defined system. An active fraction that stimulates the synthesis of these latter proteins has been obtained by fractionation of a high-speed supernatant on DEAE-cellulose. Because previous studies showed that this fraction (1 M DEAE salt eluate) contains a protein, called L factor, that stimulates beta-galactosidase synthesis in vitro, L factor was tested for activity. Although L factor stimulates the synthesis of the beta beta' subunits, it has little or no effect on the in vitro synthesis of the other products studied. In the present experiments, the ratio of L12/L10 and of EF-Tu (tufA)/EF-G formed is 4-6. These values are consistent with in vivo results.
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PMID:DNA-directed in vitro synthesis of proteins involved in bacterial transcription and translation. 16 May 61

The genetic organization and interrelationships between the two ribosomal protein transcription units (the L11 and L10 operons) from near 89 min on the Escherichia coli chromosome were studied by using insertional mutations generated by the kanamycin-resistant transposable element Tn5. The polar effects of Tn5 insertions on the expression of the L11, L1, L10, and L12 ribosomal protein genes and the beta RNA polymerase subunit gene were examined (i) by the level of beta-galactosidase activity generated from L10-lacZ and beta-lacZ gene fusions, (ii) by direct sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins specified by plasmid ribosomal protein genes in UV-irradiated maxicells, and (iii) by urea-polyacrylamide gel electrophoresis of plasmid- and chromosome-specified L12 protein. The results confirmed the organization of these genes into two transcription units as follows: PL11, rplK (L11), rplA (L1), PL10, rplJ (L10), rplL (L12), rpoB (beta). . .; they also localized the position of the PL10 promoter within an 80-nucleotide region near the end of the L1 gene. The results also support the idea that the translational regulatory proteins for the L11 and L10 operons are L1 and L10, respectively, and that the expression of the L12 gene is closely linked to L10 gene expression.
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PMID:Insertions of transposon Tn5 into ribosomal protein PNA polymerase operons. 629 59

A high-copy plasmid, pGA217, which carries a deletion (lacking the carboxy-terminal 20 amino acids) of the structural gene for ribosomal protein L10 (rplJ) is lethal to the cell in the absence of the gene (rplL) for r-proteins L7/L12, but only if the upstream operon for r-proteins L11 (rplK) and L1 (rplA) is present on the same plasmid. Measurements of beta-galactosidase activity of a hybrid protein expressed by a rplL-lacZ fusion indicated that the L10 fragment peptide which lacks the carboxy-terminal 20 amino acids is capable of exerting feedback regulation. Double transformation experiments with two compatible plasmids showed that the detrimental effect of the rplJ deletion on pGA217 can be reversed by the addition of a second plasmid which carries a functional gene for L7/L12. These two pieces of evidence suggest that the lethal effect of pGA217 is due to its property of feeding back on L7/L12 production from the chromosomal rplK gene. The upstream rplKA operon was inferred to have a cis-acting, stimulating effect on rplJ expression from the following evidence: (1) donor plasmids carrying the genes for L11 and/or L1 fail to exert a trans-acting effect, (2) deletion mutants which removed portions of rplK and/or rplA, but maintained the rplKA promoter, rplKp, still retained a severe growth-inhibiting effect. We suggest that these results can be explained by assuming that there is transcription from the rplKA promoter through rplJ and perhaps beyond.
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PMID:The lethal effect of a plasmid resulting from transcriptional readthrough of rplJ from the rplKA operon in Escherichia coli. 634 92

A derivative of bacteriophage lambda, lambda 21, has been constructed and used for the cloning of Escherichia coli DNA fragments carrying promoters. Phage lambda 21 lacks the lac promoter operator and can accept DNA fragments up to 9.8 kilobases in size at a unique HindIII restriction endonuclease site adjacent to lacZ. Recombinant phage that carry promoters are readily identified by their expression of lacZ. Lysogens of these phages in strains harboring a deletion of the chromosomal lac operon are capable of growth on lactose as sole carbon source and can be used to study some of the regulatory signals that act upon the cloned promoter. In principle, lambda 21 can be used to clone any promoter DNA sequence with HindIII termini. PJ, the primary promoter for the rplJL-rpoBC operon, and P beta, a weak promoter for rpoBC, have been cloned in lambda 21. Transcription of lacZ from PJ was found to be subjected to feedback control by ribosomal protein L10 and to a lesser extent by ribosomal protein L7/L12. This suggests a possible L10-binding site near PJ that regulates transcription from that promoter. Lysogens of the phage that carries P beta responded to two regulatory signals: a rho-sensitive termination site preceding rpoBC and induction of beta-galactosidase synthesis by rifampicin. This suggests that P beta is a bona fide promoter for rpoBC.
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PMID:Bacteriophage lambda vehicle for the direct cloning of Escherichia coli promoter DNA sequences: feedback regulation of the rplJL-rpoBC operon. 644 64

Changes in expression of ribosomal protein genes during growth and stationary phase of Streptomyces coelicolor A3(2) in liquid medium were studied. Proteins being synthesized were pulse-labelled with [35S]-methionine, separated by two-dimensional polyacrylamide gel electrophoresis, and quantified using the BioImage computer software. Most of the ribosomal proteins were synthesized throughout the life cycle. Exceptions were two proteins whose synthesis drastically decreased at the approach of stationary phase. These two proteins were identified in purified ribosomes as homologues of Escherichia coli ribosomal proteins L10 and L7/L12, using antibodies raised against fusion proteins between these ribosomal proteins and Escherichia coli beta-galactosidase. The genes (rplJ and rplL) encoding the L10 and L7/L12 proteins were contained in a 1.2 kb BamHI fragment that was cloned and sequenced. The linkage and order of the genes coincide with other L10-L7/L12 operons. However, L11 and L1 genes were not present immediately upstream of the L10 gene, as is the case for E. coli and other bacteria. Instead, two open reading frames of unknown function were found immediately upstream of the L10 gene, in an adjacent 1.9 kb BamHI fragment.
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PMID:Synthesis of ribosomal proteins during growth of Streptomyces coelicolor. 754 48