583 research outputs found
Chromosomal localization of the Tfam gene and presence of processed pseudogenes in different primates
No full textOrganization and Evolution of Metazoan Mitochondrial Genomes
No full textAlthough almost certainly derived from the same ancestral progenitor, mitochondrial genomes have followed multiple and different evolutionary pathways in various taxa; it shows great variability in terms of structure, gene content, organization and mode of expression in different organisms. Nevertheless, the evolutionary process has been frozen, in several senses, in the Metazoa, particularly with respect to genome size and gene content. As mitochondrial (mt) DNA is a relatively small, abundant and easy to isolate molecule, it has been particularly favoured as a molecular evolutionary marker and the nucleotide sequence from a large number of species has now been determined(http://www.ncbi.nlm.nih.gov/genomes/ORGANELLES/mztax_short.html). Metazoan mtDNA is, in general, a single circular molecule, although some cnidarians (Medusozoa) are known to possess atypical linear mt DNA. It is characterized by a compact arrangement, the constancy of gene content and the presence of a single noncoding region. With the exception of the replication origin region(s), the genome is saturated with intron‐less genes, lacking intronic sequence, which are often contiguous and sometimes slightly overlapping or separated by only a few nucleotides
In silico detection and experimetal validation of novel alternative transcripts of human mitochondrial transcription factor A
No full text
The smaller isoform of the mitochondrial transcription factor A has a role in the mitochondrial transcription
No full textThe mitochondrial transcription factor A (Tfam) is a mitochondrial protein encoded in the nucleus.
The gene for Tfam spans about 10 kb and consists of seven exons and six introns. In human and rat, exon 5
can splite alternatively resulting in two Tfam isoforms. In order to investigate the role of the 5Tfam isoform in
human cells, we studied its stability in vitro, then we carried out overexpression experiments in H1299 human
cell line in order to clarify the in vivo effect of this shorter isoform of Tfam. The data obtained by Real time-
PCR demonstrate that the overexpression of 5Tfam causes an increase of mitochondrial transcription, so
also this isoform as a role in the mitochondrial proc
In silico detection and experimental validation of novel alternative transcript factor A
No full textPseudogenes in metazoa: Origin and features
No full textThe complete genome sequences with their annotations are a considerable resource in
biology, particularly in understanding the global structure of the genetic material at the
molecular level. The reason why some eukaryotic genomes contain large quantities of
apparently unnecessary DNA, namely pseudogenes, while others seem to invest in more
efficient thinning processes or are equipped with protection systems against parasitic elements
still remains a mystery.
Several genome-wide surveys have been undertaken to identify pseudogenes in the
completely sequenced genome, bringing to light some differences both in their amount and
distribution. Since pseudogenes are important resources in evolutionary and comparative
genomics — as ‘molecular fossils’ — in this paper, a survey on the origins, features, abundance
and localisation of the different pseudogenes is reported. As an example of genes producing
processed pseudogenes, some experimental data obtained in the authors’ laboratories from
the study of a nuclear gene coding for the mitochondrial transcription factor A (mtTFA), a key
regulator of mitochondrial biogenesis, are also reported
Transient overexpression of an alternative spliced isoform of mitochondrial transcription factor A (Δ5TFAM) affects mitochondrial transcription in the H1299 cell line
No full textMitochondrial transcription factor A (Tfam) is necessary for both transcription and maintenance of mitochondrial DNA, it is abundant enough to wrap the entire mtDNA and thus organizes a protein-DNA complex.
The gene is estimated to span about 10 kb in mouse, in human and in rat. The sequence of the human gene contains an open reading frame of 741 bp over seven exons and encodes a protein with a molecular weight of 25 kDa. A short mRNA of Tfam, lacking exon 5 (05Tfam), was found to be widely distributed in human tissues, representing 30% of the total Tfam transcript pool. Changes in the primary structure of the protein can alter the binding propertíes of proteins, influence their intracellular localization and modify their enzymatic activity and/or protein stability by diverse mechanisms as well as other characteristics (Stamm et al., 2005). 45Tfam isoform localization and its effect on mitochondrial transcription were studied.
To analyze the localization of 05Tfam isoform a chimeric protein consisting of A5Tfam and of the green fluorescent protein GFP as visualized tag has been expressed. In vitro expression was performed by using the TNT Quick Coupled Transcription/Translation System (Promega). Proteins obtained were observed by immunoblotting. To study the effects of the alternative spliced 05Tfam on the transcriptional activity, transient overexpression of either full length Tfam or 05Tfam in H1299 celi was carried out, and reactions of Sybr Green Reaf time-PCR were then performed to observe the behaviour of Tfam, 05Tfam and of the mitochondrial transcript COI.
The results reported show that mitochondrial transcription increases eìther after full length Tfam either after 05Tfam transfection although less efficiently for the second one. These results agree with the smaller capability of 05Tfam to bind mtDNA in comparison witthe smaller capability of 05Tfam to bind mtDNA in comparison with the full length isoform
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