scholarly journals CORRELATION BETWEEN MAP POSITION AND PHENOTYPE OF CTI MUTANTS IN THE C CISTRON OF RHIZOBIUM MELILOTI PHAGE 16—3

Genetics ◽  
1980 ◽  
Vol 96 (2) ◽  
pp. 321-329
Author(s):  
Brigitta Dudás ◽  
László Orosz
Keyword(s):  
Genetic Map ◽  
Rhizobium Meliloti ◽  
Phenotypic Expression ◽  
Temperate Phage ◽  
Temperature Sensitive ◽  
Repressor Protein ◽  
Phage Strain ◽  
Interallelic Complementation

ABSTRACT Nine temperature-sensitive clear mutations (Cti) in the C cistron (coding for the repressor protein) of Rhizobium meliloti temperate phage 16—3 were characterized according to the inductive temperature, the immunity of cells lysogenic for these mutant phages to superinfection by homoimmune weak virulent mutants, the phenotype of double-ti mutants and interallelic complementation. The results indicate that mutations of similar phenotypic expression are clustered on the genetic map. Furthermore, it seems probable that the C cistron of the original phage 16—3 is identical to that of the independently isolated phage strain 36.

METHODS FOR ANALYSIS OF THE C CISTRON OF TEMPERATE PHAGE 16–3 OF RHIZOBIUM MELILOTI

Genetics ◽  
1980 ◽  
Vol 94 (2) ◽  
pp. 265-276
Author(s):  
LÁszló Orosz
Keyword(s):  
Fine Structure ◽  
Rhizobium Meliloti ◽  
Point Mutations ◽  
Cumulative Effect ◽  
Temperate Phage ◽  
Deletion Mutants ◽  
Temperature Sensitive ◽  
Structure Mapping ◽  
Repressor Protein ◽  
Sensitive Allele

ABSTRACT A series of clear mutants of the temperate phage 16-3 of Rhizobium meliloti were isolated that included various point and deletion mutants ofthe Ccistron, coding for the phage repressor. It was observed that recombinant genotypes, such as c+ and ti (temperature-sensitive allele), which form turbid plaques, can be detected quantitatively as lysogenic colonies and scored even at frequencies as low as 10-6. Point mutations, deletions and the autonomy of intracistronic second-site mutations were characterized by this method. Further analysis has shown that each possible pair from three ti mutants gave non-conditional clear recombinants. It was shown that these latter bear the two initial ti mutations, suggesting a cumulative effect of two conditional mutations on the structure of the repressor protein. The double mutants were utilized in fine-structure mapping of the Ccistron.

scholarly journals TEMPERATURE-SENSITIVE MUTATIONS OF THE NOTCH LOCUS IN DROSOPHILA MELANOGASTER

Genetics ◽  
1975 ◽  
Vol 81 (1) ◽  
pp. 143-162 ◽  
Author(s):  
David L Shellenbarger ◽  
J Dawson Mohler
Keyword(s):  
Temperature Shift ◽  
Temperature Sensitive ◽  
Spatial Differences ◽  
Region Temperature ◽  
Complex Locus ◽  
Notch Locus ◽  
Temporal And Spatial ◽  
Chemical Conditions ◽  
Interallelic Complementation ◽  
The Right

ABSTRACT Temperature-conditional mutations of the Notch locus were characterized in an attempt to understand the organization of a "complex locus" and the control of its function in development. Among 21 newly induced Notch alleles, about one-half are temperature-conditional for some effects, and three are temperature-sensitive for viability. One temperature-sensitive lethal, l(1)Nts1, is functionally non-complementing for all known effects of Notch locus mutations and maps at a single site within the locus. Among the existing alleles involved in complex patterns of interallelic complementation, Ax59d5 is found to be temperature-sensitive, while fag, spl, and l(1)N are temperature-independent. Whereas temperature-sensitive alleles map predominantly to the right-most fifth of the locus, fag, spl, and l(1)N are known to map to the left of this region. Temperature-shift experiments demonstrate that fag, spl, and l(1)N cause defects at specific, non-overlapping times in development.—We conclude (1) that the Notch locus is a single cistron (responsible for a single functional molecule, presumably a polypeptide); (2) that the right-most fifth of the locus is, at least in part, the region involved in coding for the Notch product; (3) that the complexity of interallelic complementation is a developmental effect of mutations that cause defects at selected times and spaces, and that complementation occurs because the mutant defects are temporally and spatially non-overlapping; and (4) that mutants express selected defects due to critical temporal and spatial differences in the chemical conditions controlling the synthesis or function of the Notch product. The complexity of the locus appears to reside in controlling the expression (synthesis or function) of the Notch product in development.

scholarly journals immX Immunity Region of Rhizobium Phage 16-3: Two Overlapping Cistrons of Repressor Function

2003 ◽  
Vol 185 (15) ◽  
pp. 4382-4392 ◽  
Author(s):  
Zsolt Csiszovszki ◽  
Zsuzsanna Buzás ◽  
Szabolcs Semsey ◽  
Tamás Ponyi ◽  
Péter P. Papp ◽  
...  
Keyword(s):  
Binding Sites ◽  
Inverted Repeat ◽  
Rhizobium Meliloti ◽  
Temperate Phage ◽  
Peptide Sequence ◽  
Its Sequence ◽  
Loss Of Function ◽  
Transcription Terminator ◽  
And Function ◽  
Data Banks

ABSTRACT 16-3 is a temperate phage of the symbiotic nitrogen-fixing bacterium Rhizobium meliloti 41. Its prophage state and immunity against superinfection by homoimmune phages are governed by a complex set of controls: the immC and immX repressor systems and the avirT element are all located in well-separated, distinct regions which span 25 kb on the bacteriophage chromosome. The anatomy and function of the immC region are well documented; however, fewer analyses have addressed the immX and avirT regions. We focused in this paper on the immX region and dissected it into two major parts: X U/L and X V . The X U/L part (0.6 kb) contained two overlapping cistrons, X U and X L , coding for proteins pXU and pXL, respectively. Inactivation of either gene inactivated the repressor function of the immX region. Loss-of-function mutants of X U and X L complemented each other in trans in double lysogens. The X V part (1 kb) contained a target for X U/L repressor action. Mutations at three sites in X V led to various degree of ImmX insensitivity in a hierarchic manner. Two sites (X V1 and X V3 ) exhibited the inverted-repeat structures characteristic of many repressor binding sites. However, X V1 could also be folded into a transcription terminator. Of the two immunity regions of 16-3, immX seems to be unique both in its complex genetic anatomy and in its sequence. To date, no DNA or peptide sequence homologous to that of ImmX has been found in the data banks. In contrast, immC shares properties of a number of immunity systems commonly found in temperate phages.

scholarly journals Identification of Structural Proteins of Rhizobium meliloti Temperate Phage 16-3

1982 ◽  
Vol 62 (1) ◽  
pp. 145-152 ◽  
Author(s):  
S. Erdei ◽  
B. Dudas ◽  
L. Orosz ◽  
E. Duda
Keyword(s):  
Rhizobium Meliloti ◽  
Temperate Phage ◽  
Structural Proteins

Interference of plasmid pCM194 with lysogeny of bacteriophage SP02 in Bacillus subtilis

1982 ◽  
Vol 152 (1) ◽  
pp. 284-290
Author(s):  
R Marrero ◽  
P S Lovett
Keyword(s):  
Bacillus Subtilis ◽  
Temperate Phage ◽  
Lytic Replication ◽  
Complete Loss ◽  
Temperature Sensitive ◽  
Hindiii Site ◽  
Chloramphenicol Resistance ◽  
Phenotype Characteristic ◽  
Hpaii Site ◽  
Host Component

Three observations indicated that the 2-megadalton chloramphenicol resistance plasmid pCM194 interferes with SP02 lysogeny of Bacillus subtilis. SP02 plaques formed on B. subtilis(pCM194) appeared almost clear, whereas plaques produced on plasmid-free or pUB110-containing cells contained large turbid centers. The number of phages spontaneously liberated by B. subtilis(SP02) was increased 10-fold or more when pCM194 was also present in the lysogens. Lastly, growth of B. subtilis(SP02, pCM194) for approximately 20 to 25 generations resulted in essentially complete loss of the prophage. This interference was not observed with pUB110 or pE194, and the pCM194 interference was not directed against B. subtilis temperate phage phi 105, which is unrelated to SP02. Lytic replication of SP02 appeared to be unaffected by pCM194. pCM194 interference with SP02 lysogeny was demonstrable in recombination-proficient strains and a recE mutant of B. subtilis. SP02 prophage which were noninducible due to the phage ind mutation were resistant to pCM194 interference. pCM194 interference was lost when the entire pCM194 molecule was joined at its unique HpaII site or at one of the two MboI sites to pUB110 or pUB110 derivatives. pBR322 joined to pCM194 at the same MboI site or at the HindIII site produced chimeras that retained the ability to interfere with SP02 lysogeny. A three-part plasmid constructed by joining pBR322 to pCM194 (at HindIII sites) and to pE194 (at PstI sites) was compatible with the SP02 prophage and showed a temperature-sensitive replication phenotype characteristic of the pE194 replicon. One explanation for the interference involves competition for a host component between an SP02 genome attempting to establish lysogeny and plasmids whose replication is directed by the pCM194 replicon.

Studies on mutants affecting amidophosphoribosyltransferase activity in Saccharomyces cerevisiae

1983 ◽  
Vol 29 (6) ◽  
pp. 681-688 ◽  
Author(s):  
Daniel J. Nieto ◽  
Robin A. Woods
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Enzyme Activity ◽  
Ultraviolet Light ◽  
Temperature Sensitivity ◽  
De Novo ◽  
Feedback Inhibition ◽  
Temperature Sensitive ◽  
Ethylmethane Sulphonate ◽  
Interallelic Complementation ◽  
Different Levels

Mutants at the ade4 locus of yeast were isolated following mutagenesis of ade+ and ade2 with ultraviolet light (UV), ethylmethane sulphonate, and the acridine half mustard ICR-170. Tests for interallelic complementation, osmotic remediality, temperature sensitivity, and mutagen-specific reversion were carried out on 19 mutants. Six mutants showed interallelic complementation and fell into four groups, defining three complons. Three mutants were osmotic remedial and the same three were temperature sensitive. Three mutants induced by ICR-170 gave purine-excreting revertants, designated Pur6 or ade4.RCF, after exposure to UV. Activity of amidophosphoribosyltransferase (PRPPAT) was assayed in the ade4 mutants and other alleles at this locus. The ade4 mutants lacked activity of the enzyme; the alleles su-pur+, su-pur, PUR6, and Pur6, showed different levels of activity. The enzyme was subject to feedback inhibition by AMP and IMP in su-pur+ and PUR6; su-pur was hypersensitive to inhibition by AMP, whereas Pur6 was slightly resistant. Purine synthesis de novo was shown to be repressible in su-pur+ and constitutive in PUR6 and Pur6 by following the accumulation of aminoimidazole ribotide in the presence and absence of cycloheximide. These observations were confirmed by direct assay of enzyme activity.

The detailed physical map of the temperate phage 16-3 of Rhizobium meliloti 41

1983 ◽  
Vol 191 (3) ◽  
pp. 430-433 ◽  
Author(s):  
László Dorgai ◽  
Gábor Polner ◽  
Erzsébet Jónás ◽  
Nándor Garamszegi ◽  
Zoltán Ascher ◽  
...  
Keyword(s):  
Rhizobium Meliloti ◽  
Physical Map ◽  
Temperate Phage

Antibiotic production by Pseudomonas reptilivora as a phage conversion

1979 ◽  
Vol 25 (9) ◽  
pp. 1108-1110 ◽  
Author(s):  
E. Martinez-Molina ◽  
J. Olivares
Keyword(s):  
Broad Spectrum ◽  
Antibiotic Production ◽  
Culture Conditions ◽  
Temperate Phage ◽  
Temperature Sensitive ◽  
Antimicrobial Substances ◽  
Defined Culture

The ability of Pseudomonas reptilivora to produce three broad-spectrum antimicrobial substances is easily lost when bacteria are subcultured. The study of the antibiotic production under defined culture conditions has shown that the biosynthesis of these substances depends upon the presence of a temperature-sensitive temperate phage. Antibiotic production is lost after phage induction.

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