scholarly journals A genetic map of several mutations affecting the mucopeptide layer ofEscherichia coli

1972 ◽  
Vol 20 (1) ◽  
pp. 65-74 ◽  
Author(s):  
H. J. W. Wijsman
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Fine Structure ◽  
Cell Division ◽  
Genetic Map ◽  
Genetic Relationship ◽  
Ofescherichia Coli ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Temperature Sensitive Mutants

SUMMARYSeveral temperature-sensitive mutants ofEscherichia coliwere isolated which lyse at the restrictive temperature. Some of these possess a biochemically defined lesion in cell-wall mucopeptide synthesis. Three genes, termedmurC, EandF, have been localized between theaziandleumarkers. From transductional data a fine structure map was constructed of themurmutations, establishing the order of the genes. The genetic relationship between these cell wall genes and neighbouring genes involved in cell division is discussed.

scholarly journals The characterization of an alanine racemase mutant ofEscherichia coli

1972 ◽  
Vol 20 (3) ◽  
pp. 269-277 ◽  
Author(s):  
H. J. W. Wijsman
Keyword(s):  
Escherichia Coli ◽  
Structural Gene ◽  
Ofescherichia Coli ◽  
Alanine Racemase ◽  
Temperature Sensitive ◽  
Temperature Sensitive Mutants

SUMMARYAmong temperature-sensitive mutants ofEscherichia colia strain was discovered requiring D-alanine for growth. It was proved to possess an altered alanine racemase. The structural gene for this enzyme, designatedalr, is located betweenmetBandpur A. The properties of the enzyme and its locus suggest that it is not under control of the mechanisms which regulate mucopeptide formation. A suppressor of thealrmutation was discovered neartrp, and termedmsuA.

Genetic mapping of the lytA and lytB loci of Escherichia coli, which are involved in penicillin tolerance and control of the stringent response

1992 ◽  
Vol 38 (9) ◽  
pp. 975-978 ◽  
Author(s):  
Robin E. Harkness ◽  
Wolfgang Kusser ◽  
Bei-jing Qi ◽  
Edward E. Ishiguro
Keyword(s):  
Escherichia Coli ◽  
Genetic Mapping ◽  
Key Words ◽  
Linkage Map ◽  
Stringent Response ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Temperature Sensitive Mutants ◽  
And Control

The mutations in nine independently isolated temperature-sensitive mutants of Escherichia coli, which exhibited penicillin tolerance and induction of the stringent response at the restrictive temperature, were assigned to two new loci designated lytA (7 alleles) and lytB (2 alleles) at 58 and 0.4 min on the linkage map, respectively. Key words: bacteriolysis, penicillin tolerance, stringent response.

scholarly journals TEMPERATURE-SENSITIVE MUTANTS FOR THE REPLICATION OF PLASMIDS IN ESCHERICHIA COLI I. ISOLATION AND SPECIFICITY OF HOST AND PLASMID MUTATIONS

Genetics ◽  
1973 ◽  
Vol 74 (1) ◽  
pp. 17-31
Author(s):  
David T Kingsbury ◽  
Donald R Helinski
Keyword(s):  
Escherichia Coli ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Class Iii ◽  
Host Chromosome ◽  
E Coli ◽  
Temperature Sensitive Mutants ◽  
Cole1 Plasmid ◽  
Factor Type ◽  
Cole1 Replication

ABSTRACT Temperature-sensitive mutants of Escherichia coli defective in the replication of the plasmid colicinogenic factor E1 (ColE1) were isolated following mutagenesis of E. coli K12 strain carrying the ColE1 factor. Following the mutagenic treatment an enrichment procedure utilizing the replacement of thymine with bromouracil in the ColE1 DNA duplicated at the restrictive temperature was used. The mutants isolated following this enrichment step were the result of a mutation event either in the host chromosome or in the ColE1 plasmid. The host mutants fell into three phenotypic classes based on the effect each mutation had on the maintenance of a variety of other extrachromosomal DNA elements. Phenotypic class I mutations affected all E. coli plasmids, both the I and F sex factor types as well as the ColE1 factor. Phenotypic class II mutations affected the maintenance of the ColE1 and the F sex factor type plasmids and not the I type, while phenotypic class III mutations affected only ColE1 replication. None of these mutations was found to have a significant effect on the replication of the E. coli chromosome. The plasmid-linked mutations fell into two phenotypic classes on the basis of the ability of the Flac episome to complement the mutation in the ColE1 plasmid.

scholarly journals Causal relations among cell cycle processes in Tetrahymena pyriformis. An analysis employing temperature-sensitive mutants.

1976 ◽  
Vol 71 (1) ◽  
pp. 242-260 ◽  
Author(s):  
J Frankel ◽  
L M Jenkins ◽  
L E DeBault
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Developmental Pathway ◽  
Temperature Sensitive Mutants ◽  
Oral Development ◽  
Macronuclear Division

Utilization of temperature-sensitive mutants of Tetrahymena pyriformis affected in cell division or developmental pathway selection has permitted elucidation of causal dependencies interrelating micronuclear and macronuclear replication and division, oral development, and cytokinesis. In those mutants in which cell division is specifically blocked at restrictive temperatures, micronuclear division proceeds with somewhat accelerated periodicity but maintains normal coupling to predivision oral development. Macronuclear division is almost totally suppressed in an early acting mutant (mola) that prevents formation of the fission zone, and is variably affected in other mutants (such as mo3) that allow the fission zone to form but arrest constriction. However, macronuclear DNA synthesis can proceed for about four cycles in the nondividing mutant cells. A second class of mutants (psm) undergoes a switch of developmental pathway such that cells fail to enter division but instead repeatedly carry out an unusual type of oral replacement while growing in nutrient medium at the restrictive temperature. Under these circumstances no nuclei divide, yet macronuclear DNA accumulation continues. These results suggest that (a) macronuclear division is stringently affected by restriction of cell division, (b) micronuclear division and replication can continue in cells that are undergoing the type of oral development that is characteristic of division cycles, and (c) macronuclear DNA synthesis can continue in growing cells regardless of their developmental status. The observed relationships among events are consistent with the further suggestion that the cell cycle in this organism may consist of separate clusters of events. with a varying degree of coupling among clusters. A minimal model of the Tetrahymena cell cycle that takes these phenomena into account is suggested.

scholarly journals THE SELECTION OF S. CEREVISIAE MUTANTS DEFECTIVE IN THE START EVENT OF CELL DIVISION

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 561-577 ◽  
Author(s):  
Steven I Reed
Keyword(s):  
Cell Division ◽  
Genetic Analysis ◽  
Linkage Map ◽  
Nuclear Genes ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mating Pheromone ◽  
Preliminary Characterization ◽  
Complementation Groups ◽  
Selection Of

ABSTRACT Thirty-three temperature-sensitive mutations defective in the start event of the cell division cycle of Saccharomyces cereuisiae were isolated and subjected to preliminary characterization. Complementation studies assigned these mutations to four complementation groups, one of which, cdc28, has been described previously. Genetic analysis revealed that these complementation groups define single nuclear genes, unlinked to one another. One of the three newly identified genes, cdc37, has been located in the yeast linkage map on chromosome IV, two meiotic map units distal to hom2.—Each mutation produces stage-specific arrest of cell division at start, the same point where mating pheromone interrupts division. After synchronization at start by incubation at the restrictive temperature, the mutants retain the capacity to enlarge and to conjugate.

scholarly journals LOCALIZED MUTAGENESIS FOR THE ISOLATION OF TEMPERATURE-SENSITIVE MUTANTS OF ESCHERICHIA COLI AFFECTED IN PROTEIN SYNTHESIS

Genetics ◽  
1979 ◽  
Vol 91 (2) ◽  
pp. 215-227
Author(s):  
W Scott Champney
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Temperature Sensitive ◽  
Chromosomal Locus ◽  
Ribosomal Subunits ◽  
Prolonged Incubation ◽  
Temperature Sensitive Mutants ◽  
Inhibition Of Growth ◽  
Localized Mutagenesis

ABSTRACT Two variations of the method of localized mutagenesis were used to introduce mutations into the 72 min region of the Escherichia coli chromosome. Twenty temperature-sensitive mutants, with linkage to markers in this region, have been examined. Each strain showed an inhibition of growth in liquid medium at 44°, and 19 of the mutants lost viability upon prolonged incubation at this temperature. A reduction in the rate of in vivo RNA and protein synthesis was observed for each mutant at 44°, relative to a control strain. Eleven of the mutants were altered in growth sensitivity or resistance to one or more of three ribosomal antibiotics. The incomplete assembly of ribosomal subunits was detected in nine strains grown at 44°. The characteristics of these mutants suggest that many of them are altered in genes for translational or transcriptional components, consistent with the clustering of these genes at this chromosomal locus.

Genetic Analysis of Yeast RPA1 Reveals Its Multiple Functions in DNA Metabolism

Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 989-1005 ◽  
Author(s):  
Keiko Umezu ◽  
Neal Sugawara ◽  
Clark Chen ◽  
James E Haber ◽  
Richard D Kolodner
Keyword(s):  
Dna Replication ◽  
Dna Binding ◽  
Protein A ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Physical Analysis ◽  
Single Stranded Dna ◽  
Temperature Sensitive Mutants

Abstract Replication protein A (RPA) is a single-stranded DNA-binding protein identified as an essential factor for SV40 DNA replication in vitro. To understand the in vivo functions of RPA, we mutagenized the Saccharomyces cerevisiae RFA1 gene and identified 19 ultraviolet light (UV) irradiation- and methyl methane sulfonate (MMS)-sensitive mutants and 5 temperature-sensitive mutants. The UV- and MMS-sensitive mutants showed up to 104 to 105 times increased sensitivity to these agents. Some of the UV- and MMS-sensitive mutants were killed by an HO-induced double-strand break at MAT. Physical analysis of recombination in one UV- and MMS-sensitive rfa1 mutant demonstrated that it was defective for mating type switching and single-strand annealing recombination. Two temperature-sensitive mutants were characterized in detail, and at the restrictive temperature were found to have an arrest phenotype and DNA content indicative of incomplete DNA replication. DNA sequence analysis indicated that most of the mutations altered amino acids that were conserved between yeast, human, and Xenopus RPA1. Taken together, we conclude that RPA1 has multiple roles in vivo and functions in DNA replication, repair, and recombination, like the single-stranded DNA-binding proteins of bacteria and phages.

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