scholarly journals Premature 3'-end formation of CBP1 mRNA results in the downregulation of cytochrome b mRNA during the induction of respiration in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (8) ◽  
pp. 4199-4207 ◽  
Author(s):  
K A Sparks ◽  
S A Mayer ◽  
C L Dieckmann
Keyword(s):  
Mutant Strain ◽  
Cytochrome B ◽  
Nuclear Gene ◽  
State Level ◽  
Transcript Level ◽  
Unexpected Result ◽  
Coordinate Regulation ◽  
Growth Properties ◽  
Cytochrome B Mrna ◽  
Responsive Element

The yeast mitochondrial genome encodes only seven major components of the respiratory chain and ATP synthase; more than 200 other mitochondrial proteins are encoded by nuclear genes. Thus, assembly of functional mitochondria requires coordinate expression of nuclear and mitochondrial genes. One example of coordinate regulation is the stabilization of mitochondrial COB (cytochrome b) mRNA by Cbp1, the product of the nuclear gene CBP1 (cytochrome b processing). CBP1 produces two types of transcripts with different 3' ends: full-length 2.2-kb transcripts and 1.2-kb transcripts truncated within the coding sequence of Cbp1. Upon induction of respiration, the steady-state level of the long transcripts decreases while that of the short transcripts increases reciprocally, an unexpected result since the product of the long transcripts is required for COB mRNA stability and thus for respiration. Here we have tested the hypothesis that the short transcripts, or proteins translated from the short transcripts, are also required for respiration. A protein translated from the short transcripts was not detected by Western analysis, although polysome gradient fractions were shown to contain both long and short CBP1 transcripts. A mutant strain in which production of the short transcripts was abolished showed wild-type growth properties, indicating that the short transcripts are not required for respiration. Due to mutation of the carbon source-responsive element, the long transcript level in the mutant strain did not decrease during induction of respiration. The mutant strain had increased levels of COB RNA, suggestive that production of short CBP1 transcripts is a mechanism for downregulation of the levels of long CBP1 transcripts, Cbp1, and COB mRNA during the induction of respiration.

Suppressor analyses of temperature-sensitive cbp1 strains of Saccharomyces cerevisiae: the product of the nuclear gene SOC1 affects mitochondrial cytochrome b mRNA post-transcriptionally.

Genetics ◽  
1994 ◽  
Vol 138 (3) ◽  
pp. 565-575
Author(s):  
R R Staples ◽  
C L Dieckmann
Keyword(s):  
Cytochrome B ◽  
Nuclear Gene ◽  
State Level ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Mitochondrial Cytochrome ◽  
Mitochondrial Cytochrome B ◽  
Cytochrome B Mrna ◽  
Bypass Mechanism

Abstract The induction of mitochondrial function is dependent upon both nuclearly encoded and mitochondrially encoded gene products. To understand nuclear-mitochondrial interactions, we must first understand gene-specific interactions. The accumulation of mitochondrial cytochrome b (COB) RNA is dependent upon Cbp1p, encoded by the nuclear gene CBP1. Thus, respiration is dependent upon Cbp1p. In this study, suppressors of temperature-sensitive cbp1 (cbp1ts) strains were selected for restoration of respiratory capability at the restrictive temperature Ts+). One nuclearly encoded suppressor, extragenic to CBP1, is recessive with respect to the wild-type suppressor allele and is unlinked to other known genetic loci whose gene products are necessary for expression of COB mRNA. The suppressor, called soc1 for Suppressor of cbp1, suppresses several other cbp1ts alleles but does not operate via a bypass mechanism. Molecular analyses indicate that soc1 allows the steady-state level of COB mRNA to increase at high temperature but has little or no effect on the levels of COB pre-mRNA. These data have led us to propose that the product of the nuclear gene SOC1 is required for normal turnover of COB mRNA.

In vivo analysis of sequences necessary for CBP1-dependent accumulation of cytochrome b transcripts in yeast mitochondria

1993 ◽  
Vol 13 (7) ◽  
pp. 4203-4213
Author(s):  
T M Mittelmeier ◽  
C L Dieckmann
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Gene ◽  
Microprojectile Bombardment ◽  
Nuclear Gene ◽  
State Level ◽  
Transcription Unit ◽  
Endonucleolytic Cleavage ◽  
In Vivo Analysis ◽  
Nucleotide Region

In Saccharomyces cerevisiae, cytochrome b, an essential component of the respiratory chain, is encoded by the mitochondrial gene cob. The cob transcription unit includes the tRNA(Glu) gene from positions -1170 to -1099 relative to the cob ATG at +1. The initial tRNA(Glu)-cob transcript undergoes several processing events, including removal of tRNA(Glu) and production of the mature 5' end of cob mRNA at nucleotide -954. The nuclear gene product CBP1 is specifically required for the accumulation of cob mRNA. In cbp1 mutant strains, cob transcripts are not detectable by Northern (RNA) blot analysis, but the steady-state level of tRNA(Glu) is similar to that of wild type. The results of a previous study led to the conclusion that a 400-nucleotide region just downstream of tRNA(Glu) is sufficient for CBP1 function. In the present study, the microprojectile bombardment method of mitochondrial transformation was used to introduce deletions within this region of cob. The analysis of cob transcripts in strains carrying the mitochondrial deletion genomes indicates that a 63-nucleotide sequence that encompasses the cleavage site at -954 is sufficient both for CBP1 function and for correct positioning of the cleavage. Furthermore, the data indicate that CBP1 prevents the degradation of unprocessed cob transcripts produced by endonucleolytic cleavage at the 3' end of tRNA(Glu).

scholarly journals In vivo analysis of sequences necessary for CBP1-dependent accumulation of cytochrome b transcripts in yeast mitochondria.

1993 ◽  
Vol 13 (7) ◽  
pp. 4203-4213 ◽  
Author(s):  
T M Mittelmeier ◽  
C L Dieckmann
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Gene ◽  
Microprojectile Bombardment ◽  
Nuclear Gene ◽  
State Level ◽  
Transcription Unit ◽  
Endonucleolytic Cleavage ◽  
In Vivo Analysis ◽  
Nucleotide Region

In Saccharomyces cerevisiae, cytochrome b, an essential component of the respiratory chain, is encoded by the mitochondrial gene cob. The cob transcription unit includes the tRNA(Glu) gene from positions -1170 to -1099 relative to the cob ATG at +1. The initial tRNA(Glu)-cob transcript undergoes several processing events, including removal of tRNA(Glu) and production of the mature 5' end of cob mRNA at nucleotide -954. The nuclear gene product CBP1 is specifically required for the accumulation of cob mRNA. In cbp1 mutant strains, cob transcripts are not detectable by Northern (RNA) blot analysis, but the steady-state level of tRNA(Glu) is similar to that of wild type. The results of a previous study led to the conclusion that a 400-nucleotide region just downstream of tRNA(Glu) is sufficient for CBP1 function. In the present study, the microprojectile bombardment method of mitochondrial transformation was used to introduce deletions within this region of cob. The analysis of cob transcripts in strains carrying the mitochondrial deletion genomes indicates that a 63-nucleotide sequence that encompasses the cleavage site at -954 is sufficient both for CBP1 function and for correct positioning of the cleavage. Furthermore, the data indicate that CBP1 prevents the degradation of unprocessed cob transcripts produced by endonucleolytic cleavage at the 3' end of tRNA(Glu).

Fibronectin is overproduced by keloid fibroblasts during abnormal wound healing

1989 ◽  
Vol 9 (4) ◽  
pp. 1642-1650
Author(s):  
M Babu ◽  
R Diegelmann ◽  
N Oliver
Keyword(s):  
Wound Healing ◽  
State Level ◽  
Cell Types ◽  
Relative Increase ◽  
Receptor Expression ◽  
Glucocorticoid Treatment ◽  
Fibronectin Receptor ◽  
Coordinate Regulation ◽  
Extracellular Matrix Components ◽  
Keloid Fibroblasts

Wound healing in certain individuals leads to the development of keloid tumors which exhibit abnormal collagen metabolism and an increased abundance of extracellular matrix components. Comparison of fibronectin levels in fibroblasts derived from keloids and normal dermis revealed a relative increase in intracellular and extracellular fibronectin in the keloid-derived cells. While fibronectin was similarly processed, compartmentalized, and degraded by both cell types, fibronectin biosynthesis was found to be accelerated as much as fourfold in keloid fibroblasts due to a corresponding increase in the amount of accumulated fibronectin mRNA. These changes account for the elevated steady-state level of the molecule in keloid fibroblasts and suggest that increased fibronectin in keloid lesions is due to overproduction by the wound-healing fibroblasts. Glucocorticoid treatment stimulated fibronectin biosynthesis in both normal and keloid fibroblasts. However, the amount of stimulation was less for the keloid-derived cells, indicating a limitation on maximal rates of fibronectin biosynthesis. These observations suggest that separate mechanisms act to control basal and maximal rates of fibronectin production. Biosynthesis of the 140-kilodalton fibronectin receptor was also found to be increased in keloid fibroblasts, suggesting some level of coordinate regulation for fibronectin and fibronectin receptor expression.

Yeast CBP1 mRNA 3' end formation is regulated during the induction of mitochondrial function

1991 ◽  
Vol 11 (2) ◽  
pp. 813-821
Author(s):  
S A Mayer ◽  
C L Dieckmann
Keyword(s):  
Mitochondrial Function ◽  
Developmental Stages ◽  
Single Gene ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
State Level ◽  
Yeast Cells ◽  
Cdna Clones ◽  
Coding Sequence ◽  
Polyadenylation Sites

Alternative mRNA processing is one mechanism for generating two or more polypeptides from a single gene. While many mammalian genes contain multiple mRNA 3' cleavage and polyadenylation signals that change the coding sequence of the mature mRNA when used at different developmental stages or in different tissues, only one yeast gene has been identified with this capacity. The Saccharomyces cerevisiae nuclear gene CPB1 encodes a mitochondrial protein that is required for cytochrome b mRNA stability. This 66-kDa protein is encoded by a 2.2-kb mRNA transcribed from CPB1. Previously we showed that a second 1.2-kb transcript is initiated at the CBP1 promoter but has a 3' end near the middle of the coding sequence. Furthermore, it was shown that the ratio of the steady-state level of 2.2-kb CBP1 message to 1.2-kb message decreases 10-fold during the induction of mitochondrial function, while the combined levels of both messages remain constant. Having proposed that regulation of 3' end formation dictates the amount of each CBP1 transcript, we now show that a 146-bp fragment from the middle of CBP1 is sufficient to direct carbon source-regulated production of two transcripts when inserted into the yeast URA3 gene. This fragment contains seven polyadenylation sites for the wild-type 1.2-kb mRNA, as mapped by sequence analysis of CBP1 cDNA clones. Deletion mutations upstream of the polyadenylation sites abolished formation of the 1.2-kb transcript, whereas deletion of three of the sites only led to a reduction in abundance of the 1.2-kb mRNA. Our results indicate that regulation of the abundance of both CBP1 transcripts is controlled by elements in a short segment of the gene that directs 3' end formation of the 1.2-kb transcript, a unique case in yeast cells.

Supraspecies relationships in the subfamily Arvicolinae (Rodentia, Cricetidae): An unexpected result of nuclear gene analysis

2009 ◽  
Vol 43 (5) ◽  
pp. 834-846 ◽  
Author(s):  
N. I. Abramson ◽  
V. S. Lebedev ◽  
A. S. Tesakov ◽  
A. A. Bannikova
Keyword(s):  
Nuclear Gene ◽  
Gene Analysis ◽  
Unexpected Result

Increase of Cytochrome b mRNA by Bis(2-hydroxyethyl) Trisulfide in J774A.1 Cells.

1996 ◽  
Vol 19 (6) ◽  
pp. 876-878 ◽  
Author(s):  
Yasuhiro KOHAMA ◽  
Kentaro IIDA ◽  
Susumu ITOH ◽  
Kazutake TSUJIKAWA ◽  
Tsutomu MIMURA
Keyword(s):  
Cytochrome B ◽  
Cytochrome B Mrna

scholarly journals Generation of temperature-sensitive cbp1 strains of Saccharomyces cerevisiae by PCR mutagenesis and in vivo recombination: characteristics of the mutant strains imply that CBP1 is involved in stabilization and processing of cytochrome b pre-mRNA.

Genetics ◽  
1993 ◽  
Vol 135 (4) ◽  
pp. 981-991 ◽  
Author(s):  
R R Staples ◽  
C L Dieckmann
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome B ◽  
Mitochondrial Gene ◽  
Nuclear Gene ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
In Vivo Recombination ◽  
Mutant Strains ◽  
Precursor Rna

Abstract Mitochondrial biogenesis is dependent on both nuclearly and mitochondrially encoded proteins. Study of the nuclearly encoded mitochondrial gene products and their effect on mitochondrial genome expression is essential to understanding mitochondrial function. Mutations in the nuclear gene CBP1 of Saccharomyces cerevisiae result in degradation of mitochondrially encoded cytochrome b (cob) RNA; thus, the cells are unable to respire. Putative roles for the CBP1 protein include processing of precursor RNA to yield the mature 5' end of cob mRNA and/or physical protection of the mRNA from degradation by nucleases. To examine the activity of CBP1, we generated temperature-sensitive cbp1 mutant strains by polymerase chain reaction (PCR) mutagenesis and in vivo recombination. These temperature-sensitive cbp1 strains lack cob mRNA only at the nonpermissive temperature. Quantitative primer extension analyses of RNA from these strains and from a cbp1 deletion strain demonstrated that CBP1 is required for the stability of precursor RNAs in addition to production of the stable mature mRNA. Thus, CBP1 is not involved solely in the protection of mature cob mRNA from nucleases. Moreover, we found that mature mRNAs are undetectable while precursor RNAs are reduced only slightly at the nonpermissive temperature. Collectively, these data lead us to favor a hypothesis whereby CBP1 protects cob precursor RNAs and promotes the processing event that generates the mature 5' end of the mRNA.

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