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  • 11
    Electronic Resource
    Electronic Resource
    Overlapping of the coding regions for α and γ components of penicillin-binding protein 1 b in Escherichia coli (1984)
    Springer
    Molecular genetics and genomics 196 (1984), S. 449-457 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mode of biosynthesis of penicillin-binding protein(PBP)-1 b in Escherichia coli was investigated by use of the plasmid carrying the ponB(PBP-1 b) gene region. Analyses of the products synthesized in minicells and in vitro showed that PBP-1 b was synthesized as two molecular species corresponding to the α and γ components of PBP-1 b. The coding regions for the α and γ components were located within the ca. 3.7 kb MluI-HincII fragment and transcribed in the direction from the HincII to the MluI site. The capacity for producing the α component was abolished by a deletion extending to the MluI site ca. 0.7 kb inward from the HincII end of the ca. 3.7 kb fragment; the remaining 3.0 kb region with the MluI site at both ends directed the production of the γ component alone. The production of the γ component was enough to correct all the known defects caused by a ponB mutation. In addition to these results, the analyses for cross-reacting materials produced in correspondence to the various deletions indicated that the coding regions for the α and γ components overlapped and that the N-terminal portion was responsible for the difference between the two components. The distal region about 0.7 kb long inward from the MluI end of the MluI-HincII fragment was dispensable for producing the functional PBP-1 b, although the PBP-1 b produced was curtailed. By a larger distal deletion reaching almost to the middle of the MluI-HincII fragment, the polypeptide produced for PBP-1 b lost the ability to bind penicillin and still retained a low but significant activity for glycan synthesis. We suggest, therefore, that the polypeptide portion required for transglycosylase activity resides on the N-terminal half of PBP-1 b, followed by the middle portion necessary for penicillin-binding and the C-terminal part dispensable for the function of PBP-1 b.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00436192
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  • 12
    Electronic Resource
    Electronic Resource
    A cell division regulatory mechanism controls the flagellar regulon in Escherichia coli (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 340-346 
    Details
    ISSN: 1617-4623
    Keywords: Coordination ; Cell division ; Flagellar formation ; Transcriptional level ; Ts mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation of flagella in various thermosensitive (Ts) cell division mutants of Escherichia coli was examined at the nonpermissive temperature. The number of flagella per unit cell length decreased sharply after shifting the culture temperature from 30° to 40° C in the following Ts mutants: ftsC108, ftsD1033, ftsE1181, ftsF1141, ftsG29, ftsZ84, parA110, dnaB42, nrdB, and dnaG. It was found that transcription of genes responsible for the formation and/or function of flagella (hag, fla, mot, che) decreased significantly at 40°C. However, in the ftsI730 mutant at the nonpermissive temperature, or in penicillin G treated wild-type cells, cell division was blocked but formation of flagella continued. Moreover, when the cfcA1 mutation, of a gene involved in coordinating DNA replication and cell division, was introduced into the dnaB42 mutant strain, inhibition of cell division and also of formation of flagella at 40°C was relaxed. These results indicate that the flagellar regulon is under the control of a cell division regulatory mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334374
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  • 13
    Electronic Resource
    Electronic Resource
    Dispensability of either penicillin-binding protein -1a or -1b involved in the essential process for cell elongation in Escherichia coli (1985)
    Springer
    Molecular genetics and genomics 200 (1985), S. 272-277 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A strain of Escherichia coli lacking the entire ponB gene and a strain lacking the proximal part of the ponA gene were constructed by substitution with a drug resistance gene. These strains lost either penicillin-binding protein(PBP) -1b or -1a totally and their growth was apparently normal at 30°C and 42°C except that growth of the ponB deletion strain was poor on a nutrient agar plate containing no NaCl at 30°C as well as at 42°C. Transductional experiments to introduce the ponB deletion into the ponA deletion strain, and vice versa, showed that the ponA ponB double deletion was lethal unless the deletion was functionally compensated, e.g., by the presence of a plasmid carrying either gene. Thus, either PBP-1b (ponB) or PBP-1a (ponA), but not both, is dispensable for cell viability, at least under ordinary culture conditions. Transductional experiments also suggested that the γ component of PBP-1b or the PBP-1b lacking the C-terminal portion encoded in the distal region to the SphI site on the ponB was sufficient for supporting growth of the E. coli cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425435
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  • 14
    Electronic Resource
    Electronic Resource
    Mutations affecting the structural genes and the genes coding for modifying enzymes for ribosomal proteins in Escherichia coli (1978)
    Springer
    Molecular genetics and genomics 165 (1978), S. 15-20 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Temperature-sensitive mutants of an Escherichia coli K-12 strain PA3092 have been isolated following mutagenesis with nitrosoguanidine, and their ribosomal proteins analyzed by two-dimensional gel electrophoresis This method was found to be very efficient in obtaining mutants with various structural alterations in ribosomal proteins. Thus a total of some 160 mutants with alterations in 41 different ribosomal proteins have so far been isolated. By characterizing these mutants, we could isolate, not only those mutants with alterations in the structural genes for various ribosomal proteins, but also those with impairments in the modification of proteins S5, S18 and L12. Furthermore, a mutant has been obtained which apparently lacks the protein S20 (L26) with a concomitant reduction to a great extent of the polypeptide synthetic activity of the small subunit. The usefulness of these mutants in establishing the genetic architecture of the genes coding for the ribosomal proteins and their modifiers is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270371
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  • 15
    Electronic Resource
    Electronic Resource
    Characterization of the dnaA gene carried by lambda transducing phage (1980)
    Springer
    Molecular genetics and genomics 180 (1980), S. 235-247 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Specialized transducing phages λdnaA were obtained by inducing lysogens in which λtna was integrated at the tnaA region of the Escherichia coli chromosome; the tnA region is located in the vicinity of the dnaA gene. The dnaA - deletion derivatives of λdnaA were isolated from the lysate of λdnaA grown on bacteria carrying a transposon Tn3. The structures of various transducing phages thus obtained were determined by heteroduplex DNA mapping. From these results, the transducing fragment of 13.8-kb-long was divided into nine domains. Upon infection of UV-irradiated cells with the phage, production of polypeptides of 49 kD and 42 kD was specifically associated with infections by the dnaA and recF transducing phages. Polypeptides of 49 kD and 42 kD appeared to be coded for by dnaA and recF genes, respectively. The dnaA gene was assigned to the region of 2.8-kb-long which extends by 2.4 kb in the counterclockwise direction on the E. coli genetic map and 0.4 kb in the opposite direction, as measured from the nearest HindIII site close to the tnaA gene. The recF gene was also discovered to lie very close to dnaA in the order of tnaA-dnaA-recF. Merogenotes heterozygous for the dnaA gene were constructed by introducing F′100-12 carrying λdnaA into the recipients with different mutations at or near dnaA. For combinations, F′(λdnaA +)/dnaA46 and F′(λdna +)/dna-83, dnaA + was trans-dominant, whereas the dnaA + was recessive for F′(λdnaA +)/dna-5. For F′(λdnaA +)/dna-167, the result of the transdominance test was affected by the growth media employed; dnaA + was dominant on a λ-broth plate, and dna-167 was dominant on an M9-minimal plate. Thus, transdominance of dnaA + in heterozygotes is affected by difference in mutations and growth media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425835
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  • 16
    Electronic Resource
    Electronic Resource
    Binding of penicillin to thiol-penicillin-binding protein 3 of Escherichia coli: identification of its active site (1985)
    Springer
    Molecular genetics and genomics 201 (1985), S. 499-504 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to determine the active site of penicillin-binding protein 3 of Escherichia coli (PBP3), the serine residue at position 307 was replaced with alanine, threonine or cysteine by oligonucleotide-directed site-specific mutagenesis. Since a unique BanII site exists at the position corresponding to serine-307, BanII digestion of the plasmid DNA after mutagenesis resulted in significant enrichment of the mutant plasmids. For mutagenesis, the gene coding for PBP3 (ftsI) was inserted into the expression cloning vector pIN-IIB. The hybrid protein produced was able to bind penicillin while mutant PBP3 in which serine-307 was replaced with either alanine or threonine did not lead to any detectable binding. However, contrary to the report of Broome-Smith et al. (1985) thiol-penicillin-binding protein 3, in which serine-307 was replaced with cysteine, was still able to bind penicillin. Replacement of serine-445 with an alanine residue had no effect on penicillin binding to PBP3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331346
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