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E A ADELBERG

Publications and source records attributed to E A ADELBERG.

At least 19 recordsLinked to original sources
PubMed1965

REGULATORY MECHANISMS IN THE BIOSYNTHESIS OF ISOLEUCINE AND VALINE. II. IDENTIFICATION OF TWO OPERATOR GENES.

Ramakrishnan, T. (Yale University, New Haven, Conn.), and Edward A. Adelberg. Regulatory mechanisms in the biosynthesis of isoleucine and valine. II. Identification of two operator genes. J. Bacteriol. 89:654-660. 1965.-A tightly clustered set of five structural genes governs the synthesis of the five enzymes of isoleucine and valine biosynthesis in Escherichia coli. Three of the genes governing transaminase B, dehydrase, and threonine deaminase, are controlled by a single operator locus, designated oprA. The structural gene governing the condensing enzyme is controlled by a second operator locus, designated oprB. Both oprA and oprB have been shown to regulate structural genes which are cis, but not trans, to their own operator. No mutations have yet been found which affect the level of reductoisomerase, but the existence of a third operator controlling the synthesis of this enzyme can be inferred. Enzyme derepression resulting from mutations in oprA confers resistance to high levels of valine. Derepression of the condensing enzyme resulting from mutations in oprB confers resistance to low levels of valine, and to alpha-aminobutyric acid. The significance of these findings with respect to the valine sensitivity of E. coli strain K-12 is discussed.

Amino Acids↗
PubMed1965

REGULATORY MECHANISMS IN THE BIOSYNTHESIS OF ISOLEUCINE AND VALINE. 3. MAP ORDER OF THE STRUCTURAL GENES AND OPERATOR GENES.

Ramakrishnan, T. (Yale University, New Haven, Conn.), and Edward A. Adelberg. Regulatory mechanisms in the biosynthesis of isoleucine and valine. III. Map order of the structural genes and operator genes. J. Bacteriol. 89:661-664. 1965.-A new method has been employed to determine the map order of the structural genes and operator genes governing the enzymes of the isoleucine-valine biosynthetic pathway. This method relies on the observation that phage transduction of markers carried on an F-genote leads to the establishment in the recipient of F-genotes of various lengths. Using this method, we have established that the order of loci is the following: F/ilvE ilvD ilvA oprA/ilvC/ilvB oprB. The operator locus, oprA, regulates the activity of structural genes ilvE (transaminase B), ilvD (dehydrase), and ilvA (threonine deaminase). The operator locus, oprB, regulates the activity of ilvB (condensing enzyme). An operator for ilvC (reductoisomerase) can be inferred to exist, but has not yet been detected genetically. The loci ilvB and oprB have been shown to be at the extreme right end of the sequence, but their positions relative to each other remain to be established.

Amino Acids↗
PubMed1965

GROWTH OF MALE-SPECIFIC BACTERIOPHAGE IN PROTEUS MIRABILIS HARBORING F-GENOTES DERIVED FROM ESCHERICHIA COLI.

Horiuchi, Kensuke (Yale University, New Haven, Conn.), and Edward A. Adelberg. Growth of male-specific bacteriophage in Proteus mirabilis harboring F-genotes derived from Escherichia coli. J. Bacteriol. 89:1231-1236. 1965.-Male-specific bacteriophage MS2 was shown to infect and grow in Proteus mirabilis strains which harbor F-genotes derived from Escherichia coli K-12. The burst size was 2,000 to 3,000, which is similar to that in E. coli K-12, whereas the latent period was 45 min, definitely longer than that in E. coli. In spite of the multiplication of MS2 in male P. mirabilis in broth, P. mirabilis strains failed to show plaque formation by MS2 on agar plates; this failure may be related to the low efficiency of phage adsorption. No host-controlled modification of MS2 by P. mirabilis was detected.

Bacteriophages↗
PubMed1964

REGULATORY MECHANISMS IN THE BIOSYNTHESIS OF ISOLEUCINE AND VALINE. I. GENETIC DEREPRESSION OF ENZYME FORMATION.

Ramakrishnan, T. (Yale University, New Haven, Conn.), and Edward A. Adelberg. Regulatory mechanisms in the biosynthesis of isoleucine and valine. I. Genetic derepression of enzyme formation. J. Bacteriol. 87:566-573. 1964.-A total of 60 mutants of Escherichia coli K-12 resistant to 10(-2)m valine were isolated from the valine-sensitive F' strain AB1206. Conjugation experiments showed that in five of these mutants the valine-resistance locus is closely linked to the structural genes governing isoleucine-valine biosynthesis. In these five valine-resistant mutants, three enzymes of the isoleucine-valine pathway were found to be coordinately derepressed: l-threonine deaminase, dihydroxy acid dehydrase, and transaminase B. Two other enzymes of this pathway, the condensing enzyme and the reductoisomerase, were unaffected. The mutation from valine-sensitivity to valine-resistance appears to have altered an operator locus, because the derepressed state is dominant over the repressed state in diploids heterozygous for the valine-resistance locus. The valine-resistant mutants excrete isoleucine into the medium. The significance of these findings with respect to the valine-sensitivity of E. coli K-12 and the regulation of the biosynthesis of isoleucine and valine by this organism are discussed.

Drug Resistance↗
PubMed1963

GENE TRANSFER BY F' STRAINS OF ESCHERICHIA COLI K-12. I. DELAY IN INITIATION OF CHROMOSOME TRANSFER.

Pittard, James (Yale University, New Haven, Conn.), John S. Loutit, and Edward A. Adelberg. Gene transfer by F' strains of Escherichia coli K-12. I. Delay in initiation of chromosome transfer. J. Bacteriol. 85:1394-1401. 1963.-Two different F' strains were found to transfer both F-merogenote and chromosomal markers to recipient strains. When zygotes having received different chromosomal markers from the male were selected, a high percentage of them were found to have also received F-merogenote markers under conditions in which the mating of more than one male cell with a single female cell was excluded. An analysis of the kinetics of zygote formation revealed that chromosomal markers began to be transferred from F' strains 8 to 10 min later than from their analogous Hfr strains. The rate of chromosome transfer is the same from both F' and Hfr strains, and the difference observed in kinetic experiments was shown not to be due to any difference between the sequence of chromosomal genes in the F' and Hfr strains. F' strains and Hfr strains showed no difference in ability to form specific pairs with female recipients shortly after mixing. The observed delay in the transfer of chromosomal markers from F' cells thus means that, after specific pair formation, F' cells take 8 to 10 min longer than Hfr cells to initiate chromosome transfer.

Chromosomes↗
PubMed1963

GENE TRANSFER BY F' STRAINS OF ESCHERICHIA COLI K-12. II. INTERACTION BETWEEN F-MEROGENOTE AND CHROMOSOME DURING TRANSFER.

Pittard, James (Yale University, New Haven, Conn.) and Edward A. Adelberg. Gene transfer by F' strains of Escherichia coli K-12. II. Interaction between F-merogenote and chromosome during transfer. J. Bacteriol. 85:1402-1408. 1963.-When F' strains harboring the F-merogenate F(14) are mated with female recipients, the transfer of the F-merogenote begins, in the majority of cases, before chromosome transfer. The markers on F(14) are transferred in the sequence met-1, arg-1, ilva-16, and sex-factor, met-1 being transferred first and sex-factor being transferred last, 9 min after met-1. In the class of zygotes that have received both the F-merogenote marker met-1 and the chromosomal marker xyl or mal, the gradient of recombination frequencies for the F-merogenote markers arg-1 and ilva-16 is much steeper than in the corresponding zygotes that have not received chromosomal markers. In F' strains which exhibit an increased frequency of transfer of chromosome markers, this gradient of recombination frequencies for merogenote markers is much steeper. An analysis of experiments involving an F' strain with a much shorter F-merogenote, F(16), and of a triparental mating in which F-merogenote and chromosome were transferred from different donor cells reveals that the effect of chromosome transfer on the recovery of distal F-merogenote markers in the zygotes is not due to any form of postzygotic elimination. It is suggested that, when F' strains which are transferring F-merogenote begin to transfer chromosome, the latter event causes breakage of the F-merogenote. A second consequence of this interaction is a delay of 8 to 10 min in the first appearance of chromosomal markers in the zygotes.

Chromosomes↗
PubMed1962

Transduction of the attached sex factor of Escherichia coli.

DeWitt, Susanne K. (University of California, Berkeley) and Edward A. Adelberg. Transduction of the attached sex factor of Escherichia coli. J. Bacteriol. 83:673-678. 1962.-The linkage of the sex factor to one extremity of the chromosome in Hfr cells of Escherichia coli has been confirmed by transduction experiments. In Hfr P4x-6, lac is the last marker to penetrate the female during conjugation. When lac(+) was transduced from P4x-6 into a lac(-) strain by phage Plkc, 5% cotransduction of the sex factor was observed. No cotransduction of the sex factor was observed when markers other than lac(+) were selected.The transduced males resembled the Hfr parent with respect to the site of attachment and orientation of the sex factor, the order of genetic markers transferred, and the gradient of recombination frequencies produced with a given female. When the lac(-) recipient used in the transduction carried an sfa locus in a different region of the chromosome, the over-all rate of cotransduction was tenfold lower, but the transduced males again resembled the Hfr parent in their sexual behavior.

Chromosomes↗