NUCLEAR SUPPRESSORS OF THE [POKY] CYTOPLASMIC MUTANT IN NEUROSPORA CRASSA. I. GENETICS AND RESPIRATORY PROPERTIES

1976 ◽  
Vol 18 (2) ◽  
pp. 311-324 ◽  
Author(s):  
J. Kohout ◽  
H. Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Ribosomal Proteins ◽  
Respiratory Activity ◽  
Slow Growth ◽  
Phenotypic Expression ◽  
Structure And Properties ◽  
Molecular Defects ◽  
Growth Phenotype ◽  
Slow Growth Phenotype

Six nuclear suppressors of the [poky] cytoplasmic mutant (sup-1, sup-3, sup-4, sup-5, sup-10, sup-14) have been obtained in Neurospora crassa. The sup genes suppress the slow growth phenotype of [poky], and alleviate, at least partially, the deficiency of cyanide-sensitive respiratory activity in the mycelium of this cytoplasmic mutant. The six suppressors are nonallelic, suppress the phenotypic effects of [stp-Bl] in addition to [poky], but have no effect on the phenotypic expression of the [mi-3] cytoplasmic mutant. On the basis of experimentally established molecular defects in [poky] and on the basis of hypothetical considerations, it is proposed that the sup mutations affect the structure and properties of mitochondrial ribosomal proteins.

ISOLATION AND CLASSIFICATION OF EXTRANUCLEAR MUTANTS OF NEUROSPORA CRASSA

Genetics ◽  
1972 ◽  
Vol 71 (4) ◽  
pp. 521-533
Author(s):  
H Bertrand ◽  
T H Pittenger
Keyword(s):  
Cytochrome C ◽  
Neurospora Crassa ◽  
Slow Growth ◽  
Nuclear Factor ◽  
Group Iii ◽  
Group I ◽  
Growth Phenotype ◽  
Group Ii

ABSTRACT Four extranuclear mutants, [exn-1], [exn-2],[exn-4], and [stp-C], were obtained from N-methyl-N'-nitro-N-nitrosoguanidine-treated conidia and mycelium of Neurospora crassa. The three exn mutants grow with a pronounced lag from conidia and ascospores and are female fertile, whereas [stp-C] has a stop-start growth phenotype and is female sterile. The mitochondria from all four mutants are deficient in cytochromes a+a  3 and b, but contain an excess of cytochrome c. On the basis of growth and fertility, nuclear suppressors and complementation in heteroplasmons, 16 of the extranuclear mutants now available in Neurospora can be divided into three groups. Group I consists of 8 female-fertile variants with both poky-like growth and cytochrome defects. Their slow growth is suppressed by the nuclear factor, f, but not by a second nuclear suppressor, su-1([mi-3]). They complement with group III mutants in mixed cytoplasmons. Group II is represented by a single variant, [mi-3]. It is phenotypically modified by the su-1([mi-3]) factor, but not by f. Its unique cytochrome spectrum shows a deficiency of cytochrome a, but c and b are present. It complements in heteroplasmons with group I and III mutants. Group III included 7 female-sterile variants with stopper growth phenotypes and the same cytochrome defects as group I. Group III mutants complement both with group I and II isolates, but they are unaffected by either f or su-1.

scholarly journals Transcriptional pathways associated with the slow growth phenotype of transformed Anaplasma marginale

BMC Genomics ◽  
2013 ◽  
Vol 14 (1) ◽  
pp. 272 ◽  
Author(s):  
Sebastián Aguilar Pierlé ◽  
Gena Kenitra Hammac ◽  
Guy H Palmer ◽  
Kelly A Brayton
Keyword(s):  
Slow Growth ◽  
Anaplasma Marginale ◽  
Growth Phenotype ◽  
Slow Growth Phenotype

scholarly journals Identification of Genes Required for Glucan Exopolysaccharide Production in Lactobacillus johnsonii Suggests a Novel Biosynthesis Mechanism

2020 ◽  
Vol 86 (8) ◽  
Author(s):  
Melinda J. Mayer ◽  
Alfonsina D’Amato ◽  
Ian J. Colquhoun ◽  
Gwénaëlle Le Gall ◽  
Arjan Narbad
Keyword(s):  
Slow Growth ◽  
Alternative Mechanism ◽  
Wild Type ◽  
Lactobacillus Johnsonii ◽  
Neighboring Gene ◽  
Amino Acid Homology ◽  
Content Type ◽  
Exopolysaccharide Production ◽  
Growth Phenotype ◽  
Slow Growth Phenotype

ABSTRACT Lactobacillus johnsonii FI9785 makes two capsular exopolysaccharides—a heteropolysaccharide (EPS2) encoded by the eps operon and a branched glucan homopolysaccharide (EPS1). The homopolysaccharide is synthesized in the absence of sucrose, and there are no typical glucansucrase genes in the genome. Quantitative proteomics was used to compare the wild type to a mutant where EPS production was reduced to attempt to identify proteins associated with EPS1 biosynthesis. A putative bactoprenol glycosyltransferase, FI9785_242 (242), was less abundant in the Δeps_cluster mutant strain than in the wild type. Nuclear magnetic resonance (NMR) analysis of isolated EPS showed that deletion of the FI9785_242 gene (242) prevented the accumulation of EPS1, without affecting EPS2 synthesis, while plasmid complementation restored EPS1 production. The deletion of 242 also produced a slow-growth phenotype, which could be rescued by complementation. 242 shows amino acid homology to bactoprenol glycosyltransferase GtrB, involved in O-antigen glycosylation, while in silico analysis of the neighboring gene 241 suggested that it encodes a putative flippase with homology to the GtrA superfamily. Deletion of 241 also prevented production of EPS1 and again caused a slow-growth phenotype, while plasmid complementation reinstated EPS1 synthesis. Both genes are highly conserved in L. johnsonii strains isolated from different environments. These results suggest that there may be a novel mechanism for homopolysaccharide synthesis in the Gram-positive L. johnsonii. IMPORTANCE Exopolysaccharides are key components of the surfaces of their bacterial producers, contributing to protection, microbial and host interactions, and even virulence. They also have significant applications in industry, and understanding their biosynthetic mechanisms may allow improved production of novel and valuable polymers. Four categories of bacterial exopolysaccharide biosynthesis have been described in detail, but novel enzymes and glycosylation mechanisms are still being described. Our findings that a putative bactoprenol glycosyltransferase and flippase are essential to homopolysaccharide biosynthesis in Lactobacillus johnsonii FI9785 indicate that there may be an alternative mechanism of glucan biosynthesis to the glucansucrase pathway. Disturbance of this synthesis leads to a slow-growth phenotype. Further elucidation of this biosynthesis may give insight into exopolysaccharide production and its impact on the bacterial cell.

scholarly journals Mutations in the mitochondrial ATP synthase gamma subunit suppress a slow-growth phenotype of yme1 yeast lacking mitochondrial DNA.

Genetics ◽  
1995 ◽  
Vol 140 (2) ◽  
pp. 435-442 ◽  
Author(s):  
E R Weber ◽  
R S Rooks ◽  
K S Shafer ◽  
J W Chase ◽  
P E Thorsness
Keyword(s):  
Mitochondrial Dna ◽  
Atp Synthase ◽  
Slow Growth ◽  
Carbon Sources ◽  
Nuclear Gene ◽  
Genomic Locus ◽  
Gamma Subunit ◽  
Mitochondrial Atp Synthase ◽  
Growth Phenotype ◽  
Slow Growth Phenotype

Abstract In Saccharomyces cerevisiae, inactivation of the nuclear gene YME1 causes several phenotypes associated with impairment of mitochondrial function. In addition to deficiencies in mitochondrial compartment integrity and respiratory growth, yme1 mutants grow extremely slowly in the absence of mitochondrial DNA. We have identified two genetic loci that, when mutated, act as dominant suppressors of the slow-growth phenotype of yme1 strains lacking mitochondrial DNA. These mutations only suppressed the slow-growth phenotype of yme1 strains lacking mitochondrial DNA and had no effect on other phenotypes associated with yme1 mutations. One allele of one linkage group had a collateral respiratory deficient phenotype that allowed the isolation of the wild-type gene. This suppressing mutation was in ATP3, a gene that encodes the gamma subunit of the mitochondrial ATP synthase. Recovery of two of the suppressing ATP3 alleles and subsequent sequence analysis placed the suppressing mutations at strictly conserved residues near the C terminus of Atp3p. Deletion of the ATP3 genomic locus resulted in an inability to utilize nonfermentable carbon sources. atp3 deletion strains lacking mitochondrial DNA grew slowly on glucose media but were not as compromised for growth as yme1 yeast lacking mitochondrial DNA.

scholarly journals A genetic screen to identify genes that rescue the slow growth phenotype of c-myc null fibroblasts

Oncogene ◽  
2000 ◽  
Vol 19 (29) ◽  
pp. 3330-3334 ◽  
Author(s):  
Katrien Berns ◽  
E Marielle Hijmans ◽  
Eugene Koh ◽  
George Q Daley ◽  
René Bernards
Keyword(s):  
Slow Growth ◽  
Genetic Screen ◽  
Growth Phenotype ◽  
Slow Growth Phenotype
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