Ein pseudoallel-spezifischer Suppressor bei Salmonella typhimurium

1956 ◽  
Vol 11 (6) ◽  
pp. 317-329 ◽  
Author(s):  
P. Starlinger ◽  
F. Kaudewitz
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Irradiation ◽  
Genetic Material ◽  
Suppressor Gene ◽  
Growth Characteristics ◽  
Suppressor Mutation ◽  
Deficient Mutant ◽  
Colony Type ◽  
Gene Concept ◽  
Small Colony

In Salmonella typhimurium, UV-irradiation of the histidine-deficient mutant hi-31 induced a slowly growing reversion to histidine-independence. This formed colonies much smaller than wildtype. By means of transduction the newly created character “small colony” was proved to be heritable. As demonstrated by the following experiments this was due to an independant suppressor-mutation (S-31). After UV-irradiation of hi-31/S-31 a small fraction of cells forming large colonies, revealed growth-characteristics of wildtype. After transduction of small colony type cells by phages raised on wildtype the same large colonies were obtained. Expected to be of genotype hi-31+/S-31, they were used as donor for transduction of hi-31. Both, large colonies (hi-31+/S-31) and small colonies (hi-31/S-31) were isolated, which proved to be stable in further transfers.26 histidin-requiring mutants, belonging to 4 groups, each of them characterised by the same block in histidine synthesis, were transduced with phage raised on hi-31/S-31. None of them exhibited changes of growth characteristics, resulting from the incorporation of the suppressor-gene. Thus the suppressor S-31 turned out to be pseudoallel-specific.This result is considered as evidence that pseudoalleles of the histidine series in Salmonella typhimurium not only are units of recombination but also of function of genetic material. The differences between levels of functions exhibited by units which have been called pseudoalleles by various investigators are discussed in connection with the gene concept.

scholarly journals THE NATURE OF GENETIC INSTABILITY IN AUXOTROPHS OF SALMONELLA TYPHIMURIUM REQUIRING CYSTEINE OR METHIONINE AND RESISTANT TO INHIBITION BY 1,2,4-TRIAZOLE

Genetics ◽  
1978 ◽  
Vol 89 (3) ◽  
pp. 439-451
Author(s):  
A J Kingsman ◽  
D A Smith
Keyword(s):  
Enzyme Activity ◽  
Salmonella Typhimurium ◽  
Uv Irradiation ◽  
Genetic Instability ◽  
Genetic Material ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Regulatory Regions ◽  
Gene Regulatory ◽  
Derivatives Of

ABSTRACT We tested the hypothesis that unstable suppression of auxotrophy in triazole-resistant derivatives of Cym- mutants of Salmonella typhimurium is due to reversible insertion at the Cym- site of genetic material originating in the cysALKptsHI region. We have shown that the unstable phenotype was co-transducible with markers in the cysCDHIJ region. The suppression of the Cym phenotype was recA dependent and frequencies of segregation were affected by UV irradiation. Restored enzyme activity in suppressed strains was determined by wild-type enzyme, suggesting that the unstable regions are located in cys gene regulatory regions. These results support the hypothesis. In contradiction, we found no evidence for a deletion in the cysALKptsHI region.

scholarly journals Variable Surface Protein Vmm of Mycoplasma mycoides subsp. mycoides Small Colony Type

2002 ◽  
Vol 184 (13) ◽  
pp. 3712-3722 ◽  
Author(s):  
Anja Persson ◽  
Karin Jacobsson ◽  
Lars Frykberg ◽  
Karl-Erik Johansson ◽  
François Poumarat
Keyword(s):  
Phase Variation ◽  
Surface Protein ◽  
Transcriptional Level ◽  
Colony Type ◽  
Mycoplasma Capricolum ◽  
Binding Epitope ◽  
Variable Surface ◽  
Mycoplasma Mycoides ◽  
Small Colony ◽  
Reversible Phase

ABSTRACT A variable surface protein, Vmm, of the bovine pathogen Mycoplasma mycoides subsp. mycoides small colony type (M. mycoides SC) has been identified and characterized. Vmm was specific for the SC biotype and was expressed by 68 of 69 analyzed M. mycoides SC strains. The protein was found to undergo reversible phase variation at a frequency of 9 × 10−4 to 5 × 10−5 per cell per generation. The vmm gene was present in all of the 69 tested M. mycoides SC strains and encodes a lipoprotein precursor of 59 amino acids (aa), where the mature protein was predicted to be 36 aa and was anchored to the membrane by only the lipid moiety, as no transmembrane region could be identified. DNA sequencing of the vmm gene region from ON and OFF clones showed that the expression of Vmm was regulated at the transcriptional level by dinucleotide insertions or deletions in a repetitive region of the promoter spacer. Vmm-like genes were also found in four closely related mycoplasmas, Mycoplasma capricolum subsp. capricolum, M. capricolum subsp . capripneumoniae, Mycoplasma sp. bovine serogroup 7, and Mycoplasma putrefaciens. However, Vmm could not be detected in whole-cell lysates of these species, suggesting that the proteins encoded by the vmm-like genes lack the binding epitope for the monoclonal antibody used in this study or, alternatively, that the Vmm-like proteins were not expressed.

Rhizobitoxine production by and nodulation characteristics of colony-type derivatives of Bradyrhizobium japonicum USDA 76

1988 ◽  
Vol 34 (8) ◽  
pp. 1017-1022 ◽  
Author(s):  
Jeffrey S. La Favre ◽  
Adrienne K. La Favre ◽  
Allan R. J. Eaglesham
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Functional Relationship ◽  
Ruthenium Red ◽  
Broth Culture ◽  
Colony Type ◽  
Major Function ◽  
Large Colony ◽  
Small Colony ◽  
Derivatives Of

Bradyrhizobium japonicum strain USDA 76, a rhizobitoxine producer, was found to contain two colony types, designated "small" and "large" based on colony size on agar medium. Only the small type produced detectable chlorosis-inducing toxin in culture, whereas both colony types induced chlorosis as a result of synthesis of toxin in nodules. Electron microscopy revealed that a large colony derivative, grown in broth culture, was encapsulated, whereas a small colony derivative was not, suggesting a negative functional relationship between toxin synthesis and presence of capsule. The large type also had a ruthenium red reactive extracellular layer when cultured in the soybean rhizosphere. This differential production of toxin by the colony derivatives in culture, and presumably in the rhizosphere, prompted the investigation of a proposed role of rhizobitoxine in the infection of roots of nodulation-refractory (rj1rj1) soybean; the small colony type formed fewer nodules on the (rj1rj1) isoline, indicating no major function for rhizobitoxine in the infection of (rj1rj1) soybean.

Characterization of the gene for an immunodominant 72 kDa lipoprotein of Mycoplasma mycoides subsp. mycoides small colony type

Microbiology ◽  
1996 ◽  
Vol 142 (12) ◽  
pp. 3515-3524 ◽  
Author(s):  
X. Cheng ◽  
J. Nicolet ◽  
R. Miserez ◽  
P. Kuhnert ◽  
M. Krampe ◽  
...  
Keyword(s):  
Colony Type ◽  
Mycoplasma Mycoides ◽  
Small Colony

Isolation and structural analysis of two lipid A precursors from a KDO deficient mutant of Salmonella typhimurium differing in their hexadecanoic acid content

1985 ◽  
Vol 141 (4) ◽  
pp. 353-358 ◽  
Author(s):  
Thomas Hansen-Hagge ◽  
Volker Lehmann ◽  
Ulrich Seydel ◽  
Buko Lindner ◽  
Ulrich Z�hringer
Keyword(s):  
Structural Analysis ◽  
Salmonella Typhimurium ◽  
Acid Content ◽  
Lipid A ◽  
Deficient Mutant ◽  
Hexadecanoic Acid

scholarly journals Episomic suppression of phenotype in Salmonella

1964 ◽  
Vol 5 (2) ◽  
pp. 269-281 ◽  
Author(s):  
P. F. Smith-Keary ◽  
G. W. P. Dawson
Keyword(s):  
Gene Expression ◽  
Salmonella Typhimurium ◽  
Uv Irradiation ◽  
Complementation Group ◽  
Wild Type ◽  
Complementation Groups

1. An auxotroph of Salmonella typhimurium, pro-401, was isolated in a strain that was unstable at the su-leuA locus. The auxotrophy of pro-401 is probably due to the attachment of a controlling episome to the proline region of the genome where it suppresses gene expression.2. The controlling episome frequently transposes over short distances so that all clones consist of cells, mixed for the site at which the controlling episome is attached; homologous transductions yield prototrophs.3. The controlling episome can transpose to a different complementation group; homologous transductions yield abortive transductants; syntrophism occurs between cells that are ‘mutant’ in different complementation groups to give reversions consisting entirely of auxotrophic cells which are called auxotrophic reversions.4. The controlling episome transposes over very short distances and never to beyond the limits of this proline region of the genome; no wild-type reversions were found.5. The controlling episome can be located at relatively distant proline sites in different clones; prototrophs from transductions between clones that are separated by many subculturings can be 100 times more frequent than from homologous transductions.6. The controlling episome has its frequency of transposition to different complementation groups increased by UV; irradiation increases the frequency of auxotrophic reversions.7. The controlling episome continues to transpose in stored cells.8. The pattern of reversions of pro-401 is different in these studies from its pattern two years previously. This is discussed.

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