scholarly journals Why Chloroplasts and Mitochondria Contain Genomes

2003 ◽  
Vol 4 (1) ◽  
pp. 31-36 ◽  
Author(s):  
John F. Allen
Keyword(s):  
Gene Expression ◽  
Great Majority ◽  
Selective Advantage ◽  
Eukaryotic Cell ◽  
Host Cells ◽  
Mitochondrial Proteins ◽  
Control Of Gene Expression ◽  
Protein Precursor ◽  
Cellular Compartments

Chloroplasts and mitochondria originated as bacterial symbionts. The larger, host cells acquired genetic information from their prokaryotic guests by lateral gene transfer. The prokaryotically-derived genes of the eukaryotic cell nucleus now function to encode the great majority of chloroplast and mitochondrial proteins, as well as many proteins of the nucleus and cytosol. Genes are copied and moved between cellular compartments with relative ease, and there is no established obstacle to successful import of any protein precursor from the cytosol. Yet chloroplasts and mitochondria have not abdicated all genes and gene expression to the nucleus and to cytosolic translation. What, then, do chloroplast- and mitochondrially-encoded proteins have in common that confers a selective advantage on the cytoplasmic location of their genes? The proposal advanced here is that co-location of chloroplast and mitochondrial genes with their gene products is required for rapid and direct regulatory coupling. Redox control of gene expression is suggested as the common feature of those chloroplast and mitochondrial proteins that are encodedin situ. Recent evidence is consistent with this hypothesis, and its underlying assumptions and predictions are described.

scholarly journals The function of genomes in bioenergetic organelles

2003 ◽  
Vol 358 (1429) ◽  
pp. 19-38 ◽  
Author(s):  
John F. Allen
Keyword(s):  
Common Property ◽  
De Novo ◽  
Eukaryotic Cell ◽  
Host Cells ◽  
Oxygenic Photosynthesis ◽  
Testable Hypothesis ◽  
Current Evidence ◽  
Protein Precursor ◽  
The Common ◽  
Cellular Compartments

Mitochondria and chloroplasts are energy-transducing organelles of the cytoplasm of eukaryotic cells. They originated as bacterial symbionts whose host cells acquired respiration from the precursor of the mitochondrion, and oxygenic photosynthesis from the precursor of the chloroplast. The host cells also acquired genetic information from their symbionts, eventually incorporating much of it into their own genomes. Genes of the eukaryotic cell nucleus now encode most mitochondrial and chloroplast proteins. Genes are copied and moved between cellular compartments with relative ease, and there is no obvious obstacle to successful import of any protein precursor from the cytosol. So why are any genes at all retained in cytoplasmic organelles? One proposal is that these small but functional genomes provide a location for genes that is close to, and in the same compartment as, their gene products. This co-location facilitates rapid and direct regulatory coupling. Redox control of synthesis de novo is put forward as the common property of those proteins that must be encoded and synthesized within mitochondria and chloroplasts. This testable hypothesis is termed CORR, for co -location for r edox r egulation. Principles, predictions and consequences of CORR are examined in the context of competing hypotheses and current evidence.

Mouse homeo-genes within a subfamily, Hox-1.4, -2.6 and -5.1, display similar anteroposterior domains of expression in the embryo, but show stage- and tissue-dependent differences in their regulation

Development ◽  
1989 ◽  
Vol 107 (1) ◽  
pp. 131-141 ◽  
Author(s):  
S.J. Gaunt ◽  
R. Krumlauf ◽  
D. Duboule
Keyword(s):  
Gene Expression ◽  
Central Nervous System ◽  
Nervous System ◽  
In Situ Hybridization ◽  
Gene Duplication ◽  
Selective Advantage ◽  
New Findings ◽  
The Central Nervous System ◽  
Embryo Sections

By use of in situ hybridization experiments on mouse embryo sections, we compare the transcript patterns of three homeo-genes from the Hox-1.4 subfamily (Hox-1.4, -2.6 and -5.1). Genes within a subfamily are true homologues, present in the genome as a result of duplication of an ancestral homeo-gene cluster. We show that Hox-1.4, -2.6 and -5.1 are similar, although apparently not identical, in the limits of their transcript domains along the anteroposterior axis. Within the prevertebral column of the 12 1/2 day embryo, for example, the anterior boundary of transcripts for each of the three genes was most obvious at the junction of the first and second prevertebrae. Similarly, all three genes showed an anterior boundary of transcripts within the central nervous system that was located in the mid-myelencephalon of the hindbrain. Both in the prevertebral column and hindbrain, however, Hox-2.6 and Hox-5.1 transcripts extended slightly anterior to the anteriormost limits detected for Hox-1.4. In spite of close similarities in the positions of their transcript domains, Hox-1.4, -2.6 and -5.1 displayed striking stage- and tissue-dependent differences in the relative abundance of their transcripts. For example, Hox-5.1 transcripts were abundant within mesoderm and ectoderm of early stages (8 1/2 and 9 1/2 days), yet were detected only weakly in mesodermal components of the lung and stomach at 10 1/2 days, and were apparently absent from these tissues at 12 1/2 days. In contrast, Hox-1.4 and Hox-2.6 transcripts were relatively weakly detected at 8 1/2 and 9 1/2 days, but were abundant within the lung and stomach at 12 1/2 days. Our findings suggest, but do not prove, that genes within the Hox-1.4 subfamily might be coordinately regulated in their expression. We discuss the patterns of mouse homeo-gene expression now observed in terms of models originally devised for Drosophila. We also propose how our new findings may help to explain any selective advantage to the vertebrates of homeo-gene duplication to form subfamilies.

scholarly journals The Major RNA-Binding Protein ProQ Impacts Virulence Gene Expression inSalmonella entericaSerovar Typhimurium

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Alexander J. Westermann ◽  
Elisa Venturini ◽  
Mikael E. Sellin ◽  
Konrad U. Förstner ◽  
Wolf-Dietrich Hardt ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Enteric Bacteria ◽  
Host Cells ◽  
Dependent Manner ◽  
Control Of Gene Expression

ABSTRACTFinO domain proteins such as ProQ of the model pathogenSalmonella entericahave emerged as a new class of major RNA-binding proteins in bacteria. ProQ has been shown to target hundreds of transcripts, including mRNAs from many virulence regions, but its role, if any, in bacterial pathogenesis has not been studied. Here, using a Dual RNA-seq approach to profile ProQ-dependent gene expression changes asSalmonellainfects human cells, we reveal dysregulation of bacterial motility, chemotaxis, and virulence genes which is accompanied by altered MAPK (mitogen-activated protein kinase) signaling in the host. Comparison with the other major RNA chaperone inSalmonella, Hfq, reinforces the notion that these two global RNA-binding proteins work in parallel to ensure full virulence. Of newly discovered infection-associated ProQ-bound small noncoding RNAs (sRNAs), we show that the 3′UTR-derived sRNA STnc540 is capable of repressing an infection-induced magnesium transporter mRNA in a ProQ-dependent manner. Together, this comprehensive study uncovers the relevance of ProQ forSalmonellapathogenesis and highlights the importance of RNA-binding proteins in regulating bacterial virulence programs.IMPORTANCEThe protein ProQ has recently been discovered as the centerpiece of a previously overlooked “third domain” of small RNA-mediated control of gene expression in bacteria. Asin vitrowork continues to reveal molecular mechanisms, it is also important to understand how ProQ affects the life cycle of bacterial pathogens as these pathogens infect eukaryotic cells. Here, we have determined how ProQ shapesSalmonellavirulence and how the activities of this RNA-binding protein compare with those of Hfq, another central protein in RNA-based gene regulation in this and other bacteria. To this end, we apply global transcriptomics of pathogen and host cells during infection. In doing so, we reveal ProQ-dependent transcript changes in key virulence and host immune pathways. Moreover, we differentiate the roles of ProQ from those of Hfq during infection, for both coding and noncoding transcripts, and provide an important resource for those interested in ProQ-dependent small RNAs in enteric bacteria.

Molecular and Microscopic Analysis of Altered Gene Expression in Transgenic and Gene Targeted Mice

1996 ◽  
Vol 54 ◽  
pp. 12-13
Author(s):  
W. K. Jones ◽  
J. Robbins
Keyword(s):  
Gene Expression ◽  
Pulmonary Veins ◽  
Microscopic Analysis ◽  
Mouse Tissue ◽  
Adult Heart ◽  
Heavy Chains ◽  
Altered Gene Expression ◽  
Altered Gene ◽  
Pulmonary Myocardium

Two myosin heavy chains (MyHC) are expressed in the mammalian heart and are differentially regulated during development. In the mouse, the α-MyHC is expressed constitutively in the atrium. At birth, the β-MyHC is downregulated and replaced by the α-MyHC, which is the sole cardiac MyHC isoform in the adult heart. We have employed transgenic and gene-targeting methodologies to study the regulation of cardiac MyHC gene expression and the functional and developmental consequences of altered α-MyHC expression in the mouse.We previously characterized an α-MyHC promoter capable of driving tissue-specific and developmentally correct expression of a CAT (chloramphenicol acetyltransferase) marker in the mouse. Tissue surveys detected a small amount of CAT activity in the lung (Fig. 1a). The results of in situ hybridization analyses indicated that the pattern of CAT transcript in the adult heart (Fig. 1b, top panel) is the same as that of α-MyHC (Fig. 1b, lower panel). The α-MyHC gene is expressed in a layer of cardiac muscle (pulmonary myocardium) associated with the pulmonary veins (Fig. 1c). These studies extend our understanding of α-MyHC expression and delimit a third cardiac compartment.

A Review on Important Histone Acetyltransferase (HAT) Enzymes as Targets for Cancer Therapy

2019 ◽  
Vol 15 (2) ◽  
pp. 120-130
Author(s):  
Mohammad Ghanbari ◽  
Reza Safaralizadeh ◽  
Kiyanoush Mohammadi
Keyword(s):  
Gene Expression ◽  
Histone Acetyltransferase ◽  
Critical Role ◽  
Cancer Treatments ◽  
Control Of Gene Expression ◽  
Post Translational Modifications ◽  
Therapeutic Drugs ◽  
The Status ◽  
Acetyl Group ◽  
Increase Gene Expression

At the present time, cancer is one of the most lethal diseases worldwide. There are various factors involved in the development of cancer, including genetic factors, lifestyle, nutrition, and so on. Recent studies have shown that epigenetic factors have a critical role in the initiation and development of tumors. The histone post-translational modifications (PTMs) such as acetylation, methylation, phosphorylation, and other PTMs are important mechanisms that regulate the status of chromatin structure and this regulation leads to the control of gene expression. The histone acetylation is conducted by histone acetyltransferase enzymes (HATs), which are involved in transferring an acetyl group to conserved lysine amino acids of histones and consequently increase gene expression. On the basis of similarity in catalytic domains of HATs, these enzymes are divided into different groups such as families of GNAT, MYST, P300/CBP, SRC/P160, and so on. These enzymes have effective roles in apoptosis, signaling pathways, metastasis, cell cycle, DNA repair and other related mechanisms deregulated in cancer. Abnormal activation of HATs leads to uncontrolled amplification of cells and incidence of malignancy signs. This indicates that HAT might be an important target for effective cancer treatments, and hence there would be a need for further studies and designing of therapeutic drugs on this basis. In this study, we have reviewed the important roles of HATs in different human malignancies.

Sign in / Sign up

Export Citation Format

Share Document