scholarly journals Requirement of different mitochondrial targeting sequences of the yeast mitochondrial transcription factor Mtf1p when synthesized in alternative translation systems

2004 ◽  
Vol 383 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Tapan K. BISWAS ◽  
Godfrey S. GETZ

Mitochondrial (mt) translocation of the nuclearly encoded mt transcription factor Mtf1p appears to occur independent of a cleavable presequence, mt receptor, mt membrane potential or ATP [Biswas and Getz (2002) J. Biol. Chem. 277, 45704–45714]. To understand further the import strategy of Mtf1p, we investigated the import of the wild-type and N-terminal-truncated Mtf1p mutants synthesized in two different in vitro translation systems. These Mtf1p derivatives were generated either in the RRL (rabbit reticulocyte lysate) or in the WGE (wheat germ extract) translation system. Under the in vitro import conditions, the RRL-synthesized full-length Mtf1p but not the N-terminal-truncated Mtf1p product was efficiently imported into mitochondria, suggesting that the N-terminal sequence is important for its import. On the other hand, when these Mtf1p products were generated in the WGE system, surprisingly, the N-terminal-truncated products, but not the full-length protein, were effectively translocated into mitochondria. Despite these differences between the translation systems, in both cases, import occurs at a low temperature and has no requirement for a trypsin-sensitive mt receptor, mt membrane potential or ATP hydrolysis. Together, these observations suggest that, in the presence of certain cytoplasmic factors (derived from either RRL or WGE), Mtf1p is capable of using alternative import signals present in different regions of the protein. This appears to be the first example of usage of different targeting sequences for the transport of a single mt protein into the mt matrix.

2000 ◽  
Vol 14 (7) ◽  
pp. 817-829
Author(s):  
Lyubov A. Ryabova ◽  
Thomas Hohn

The shunt model predicts that small ORFs (sORFs) within the cauliflower mosaic virus (CaMV) 35S RNA leader and downstream ORF VII are translated by different mechanisms, that is, scanning–reinitiation and shunting, respectively. Wheat germ extract (WGE) and rabbit reticulocyte lysate (RRL) in vitro translation systems were used to discriminate between these two processes and to study the mechanism of ribosomal shunt. In both systems, expression downstream of the leader occurred via ribosomal shunt under the control of a stable stem and a small ORF preceding it. Shunting ribosomes were also able to initiate quite efficiently at non-AUG start codons just downstream of the shunt landing site in WGE but not in RRL. The short sORF MAGDIS from the mammalian AdoMetDC RNA, which conditionally suppresses reinitiation at a downstream ORF, prevented shunting if placed at the position of sORF A, the 5′-proximal ORF of the CaMV leader. We have demonstrated directly that sORF A is translated and that proper termination of translation at the 5′-proximal ORF is absolutely required for both shunting and linear ribosome migration. These findings strongly indicate that shunting is a special case of reinitiation.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yue Wu ◽  
Zhenling Cui ◽  
Yen-Hua Huang ◽  
Simon J. de Veer ◽  
Andrey V. Aralov ◽  
...  

AbstractAdvances in peptide and protein therapeutics increased the need for rapid and cost-effective polypeptide prototyping. While in vitro translation systems are well suited for fast and multiplexed polypeptide prototyping, they suffer from misfolding, aggregation and disulfide-bond scrambling of the translated products. Here we propose that efficient folding of in vitro produced disulfide-rich peptides and proteins can be achieved if performed in an aggregation-free and thermodynamically controlled folding environment. To this end, we modify an E. coli-based in vitro translation system to allow co-translational capture of translated products by affinity matrix. This process reduces protein aggregation and enables productive oxidative folding and recycling of misfolded states under thermodynamic control. In this study we show that the developed approach is likely to be generally applicable for prototyping of a wide variety of disulfide-constrained peptides, macrocyclic peptides with non-native bonds and antibody fragments in amounts sufficient for interaction analysis and biological activity assessment.


1983 ◽  
Vol 38 (3-4) ◽  
pp. 277-281
Author(s):  
M. E. John ◽  
W. Knöchel

Addition of cyclic AMP to normal rabbit reticulocyte lysate brings about substantial increase in protein synthesis programmed by both nuclear and polysomal eukaryotic RNAs. The increase in synthesis is largely nonspecific and the in-vitro translation system is rendered viable for longer periods of time than in the absence of cyclic AMP. This stimulation of translation could be due to the inhibition of protein kinases that are initially activated by secondary structure of RNAs. However, the ability of cyclic AMP to further stimulate methyl mercury or heat denatured RNA indicates that additional mechanisms may be involved in the enhancement of translation


RNA ◽  
2001 ◽  
Vol 7 (5) ◽  
pp. 765-773 ◽  
Author(s):  
RICHARD J. JACKSON ◽  
SAWSAN NAPTHINE ◽  
IAN BRIERLEY

2012 ◽  
Vol 53 (3) ◽  
pp. 602-602
Author(s):  
K. Murota ◽  
Y. Hagiwara-Komoda ◽  
K. Komoda ◽  
H. Onouchi ◽  
M. Ishikawa ◽  
...  

RNA ◽  
2008 ◽  
Vol 14 (3) ◽  
pp. 593-602 ◽  
Author(s):  
V. V. Zeenko ◽  
C. Wang ◽  
M. Majumder ◽  
A. A. Komar ◽  
M. D. Snider ◽  
...  

1993 ◽  
Vol 13 (3) ◽  
pp. 1951-1961
Author(s):  
M A Parisi ◽  
B Xu ◽  
D A Clayton

Human mitochondrial transcription factor A is a 25-kDa protein that binds immediately upstream of the two major mitochondrial promoters, thereby leading to correct and efficient initiation of transcription. Although the nature of yeast mitochondrial promoters is significantly different from that of human promoters, a potential functional homolog of the human transcriptional activator protein has been previously identified in yeast mitochondria. The importance of the yeast protein in yeast mitochondrial DNA function has been shown by inactivation of its nuclear gene (ABF2) in Saccharomyces cerevisiae cells resulting in loss of mitochondrial DNA. We report here that the nuclear gene for human mitochondrial transcription factor A can be stably expressed in yeast cells devoid of the yeast homolog protein. The human protein is imported efficiently into yeast mitochondria, is processed correctly, and rescues the loss-of-mitochondrial DNA phenotype in a yeast abf2 strain, thus functionally substituting for the yeast protein. Both human and yeast proteins affect yeast mitochondrial transcription initiation in vitro, suggesting that the two proteins may have a common role in this fundamental process.


Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 2767-2777 ◽  
Author(s):  
J.L. Villano ◽  
F.N. Katz

Genes capable of translating positional information into regulated growth lie at the heart of morphogenesis, yet few genes with this function have been identified. Mutants in the Drosophila four-jointed (fj) gene show reduced growth and altered differentiation only within restricted sectors of the proximal-distal (PD) axis in the leg and wing, thus fj is a candidate for a gene with this coordination function. Consistent with a position-sensitive role, we show that fj is expressed in a regional pattern in the developing leg, wing, eye and optic lobe. The fj gene encodes a novel type II membrane glycoprotein. When the cDNA is translated in an in vitro translation system in the presence of exogenous microsomal membranes, the intralumenal portion of some of the molecules is cleaved, yielding a secreted C-terminal fragment. We propose that fj encodes a secreted signal that functions as a positive regulator of regional growth and differentiation along the PD axis of the imaginal discs.


1987 ◽  
Vol 7 (5) ◽  
pp. 1848-1855
Author(s):  
G M Small ◽  
T Imanaka ◽  
H Shio ◽  
P B Lazarow

Newly synthesized peroxisomal proteins enter preexisting peroxisomes posttranslationally in vivo, generally without proteolytic processing. An efficient reconstitution of this process in vitro together with cloned DNAs for peroxisomal proteins would make possible investigation of the molecular information that targets proteins to peroxisomes. We have previously reported the isolation of clones for Candida tropicalis peroxisomal proteins; here we describe the association (and possible import) of peroxisomal proteins with peroxisomes in vitro. C. tropicalis was grown in a medium containing Brij 35, resulting in the induction of a moderate number of medium-sized peroxisomes. These peroxisomes, isolated in a sucrose gradient, had a catalase latency of 54% and were sufficiently stable to be concentrated and used in an import assay. The reticulocyte lysate translation products of total RNA from oleate-grown cells were incubated with the peroxisomes at 26 degrees C in the presence of 50 mM KCl, protease inhibitors, 0.5 M sucrose, 2.5 mM MOPS (morpholinepropanesulfonic acid) (pH 7.2), and 0.5 mM EDTA. Ten major translation products (which could be immunoprecipitated with antiserum against peroxisomal protein) became progressively associated with the peroxisomes during the first 30 min of incubation (some up to approximately 70%). These include acyl coenzyme A oxidase and the trifunctional protein hydratase-dehydrogenase-epimerase. This association did not occur at 4 degrees C nor did it occur if the peroxisomes were replaced with mitochondria.


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