scholarly journals Fates of Sec, Tat, and YidC Translocases in Mitochondria and Other Eukaryotic Compartments

2021 ◽  
Author(s):  
Markéta Petrů ◽  
Vít Dohnálek ◽  
Zoltán Füssy ◽  
Pavel Doležal
Keyword(s):  
Genetic Control ◽  
Mitochondrial Function ◽  
Protein Export ◽  
The Other ◽  
Mitochondrial Proteins ◽  
Endomembrane System ◽  
Inner Membrane ◽  
Bacterial Endosymbiont ◽  
Single Substrate ◽  
Host Nucleus

Abstract Formation of mitochondria by the conversion of a bacterial endosymbiont was a key moment in the evolution of eukaryotes. It was made possible by outsourcing the endosymbiont’s genetic control to the host nucleus, while developing the import machinery for proteins synthesized on cytosolic ribosomes. The original protein export machines of the nascent organelle remained to be repurposed or were completely abandoned. This review follows the evolutionary fates of three prokaryotic inner membrane translocases Sec, Tat, and YidC. Homologs of all three translocases can still be found in current mitochondria, but with different importance for mitochondrial function. Although the mitochondrial YidC homolog, Oxa1, became an omnipresent independent insertase, the other two remained only sporadically present in mitochondria. Only a single substrate is known for the mitochondrial Tat and no function has yet been assigned for the mitochondrial Sec. Finally, this review compares these ancestral mitochondrial proteins with their paralogs operating in the plastids and the endomembrane system.

scholarly journals Cytosolic Ni(II) Sensor in Cyanobacterium

2012 ◽  
Vol 287 (15) ◽  
pp. 12142-12151 ◽  
Author(s):  
Andrew W. Foster ◽  
Carl J. Patterson ◽  
Rafael Pernil ◽  
Corinna R. Hess ◽  
Nigel J. Robinson
Keyword(s):  
Coordination Sphere ◽  
Promoter Region ◽  
Nitrilotriacetic Acid ◽  
The Other ◽  
Cryptic Promoter ◽  
Difference Spectra ◽  
Inner Membrane ◽  
Fura 2 ◽  
Metal Selectivity ◽  
Metal Sensors

Efflux of surplus Ni(II) across the outer and inner membranes of Synechocystis PCC 6803 is mediated by the Nrs system under the control of a sensor of periplasmic Ni(II), NrsS. Here, we show that the product of ORF sll0176, which encodes a CsoR/RcnR-like protein now designated InrS (for internal nickel-responsive sensor), represses nrsD (NrsD is deduced to efflux Ni(II) across the inner membrane) from a cryptic promoter between the final two ORFs in the nrs operon. Transcripts initiated from the newly identified nrsD promoter accumulate in response to nickel or cobalt but not copper, and recombinant InrS forms specific, Ni(II)-inhibited complexes with the nrsD promoter region. Metal-dependent difference spectra of Ni(II)- and Cu(I)-InrS are similar to Cu(I)-sensing CsoR and dissimilar to Ni(II)/Co(II)-sensing RcnR, consistent with factors beyond the primary coordination sphere switching metal selectivity. Competition with chelators mag-fura-2, nitrilotriacetic acid, EDTA, and EGTA estimate KD Ni(II) for the tightest site of InrS as 2.05 (±1.5) × 10−14m, and weaker KD Ni(II) for the cells' metal sensors of other types: Zn(II) co-repressor Zur, Co(II) activator CoaR, and Zn(II) derepressor ZiaR. Ni(II) transfer to InrS occurs upon addition to Ni(II) forms of each other sensor. InrS binds Ni(II) sufficiently tightly to derepress Ni(II) export at concentrations below KD Ni(II) of the other sensors.

Abstract 332: Mitochondrial Inner-Membrane Potential Instability Promotes Sarcolemmal Electrical Instability after Ischemia-Reperfusion in Monolayers of Cardiac Myocytes

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Soroosh Solhjoo ◽  
Brian O’Rourke
Keyword(s):  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Function ◽  
Ischemia Reperfusion ◽  
Neonatal Rat ◽  
Partial Recovery ◽  
Mitochondrial Network ◽  
Electrical Excitability ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane

Mitochondrial uncoupling due to oxidative stress can, through opening of sarcolemmal KATP channels, alter cellular electrical excitability, and it has been proposed that mitochondrial function is a major factor in arrhythmogenesis during ischemia-reperfusion. Here, we examine the effects of ischemia-reperfusion on mitochondrial inner membrane potential (ΔΨm) and corresponding changes in electrical excitability and wave propagation in monolayer cultures of neonatal rat ventricular myocytes. Changes in ΔΨm were observed using TMRM and changes in the sarcolemmal voltage were recorded with a 464-element photodiode array using di-4-ANEPPS. Ischemia was induced by covering the center part of the monolayer (D = 22 mm) with a coverslip (D = 15 mm). Cell contractions ceased after approximately 6 min of ischemia; however, electrical activity continued for 11.3 ± 4.2 min (N = 5). Amplitude and conduction velocity of the action potentials in the ischemic region decreased over the same time period. ΔΨm was lost in two phases: a reversible phase of partial depolarization, after 11.2 ± 1.3 min of ischemia, and a nonreversible phase, which happened after 30 ± 6 min of ischemia, during which the whole mitochondrial network of the myocyte became depolarized and the cells underwent contracture (N = 4). Reperfusion after the long ischemia resulted in only partial recovery and the observance of oscillations of ΔΨm in the mitochondrial network or rapid flickering of individual mitochondrial clusters and was associated with heterogeneous electrical recovery, and formation of wavelets and reentry (4/5 monolayers). In contrast, mitochondria fully recovered and reentry was rare (1/5 monolayers) for reperfusion after the short ischemia (10-12 min). 4’-chlorodiazepam, an inhibitor of inner membrane anion channels, stabilized mitochondrial function after the long ischemia, and prevented wavelets (5/5 monolayers) and reentry (4/5 monolayers). In conclusion, incomplete or unstable recovery of mitochondrial function after ischemia correlates with reentrant arrhythmias in monolayers of cardiac myocytes. Our findings suggest that stabilization of mitochondrial network dynamics is an important strategy for preventing ischemia/reperfusion-related arrhythmias.

scholarly journals Protein Export across the Inner Membrane of Mitochondria

2003 ◽  
Vol 279 (4) ◽  
pp. 2507-2512 ◽  
Author(s):  
Johannes M. Herrmann ◽  
Nathalie Bonnefoy
Keyword(s):  
Protein Export ◽  
Inner Membrane

scholarly journals Constitutive Expression of Escherichia coli tat Genes Indicates an Important Role for the Twin-Arginine Translocase during Aerobic and Anaerobic Growth

2001 ◽  
Vol 183 (5) ◽  
pp. 1801-1804 ◽  
Author(s):  
Rachael L. Jack ◽  
Frank Sargent ◽  
Ben C. Berks ◽  
Gary Sawers ◽  
Tracy Palmer
Keyword(s):  
Constitutive Expression ◽  
Protein Export ◽  
The Other ◽  
Anaerobic Growth ◽  
Transcription Start ◽  
Transcription Start Sites ◽  
Expression Studies ◽  
Twin Arginine Translocase ◽  
Aerobic And Anaerobic Growth ◽  
Aerobic And Anaerobic

ABSTRACT The transcription start sites for the tatABCD andtatE loci, encoding components of the Tat (twin-arginine translocase) protein export pathway, have been identified. Expression studies indicate that the tatABCD and tatEtranscription units are expressed constitutively. Translational fusion experiments suggest that TatA is synthesized at a much higher level than the other Tat proteins.

Strangers in strange lands: mitochondrial proteins found at extra-mitochondrial locations

2019 ◽  
Vol 476 (1) ◽  
pp. 25-37 ◽  
Author(s):  
David P. Scanlon ◽  
Michael W. Salter
Keyword(s):  
Mitochondrial Genome ◽  
Mitochondrial Function ◽  
Mitochondrial Proteins ◽  
Dual Citizenship ◽  
Mitochondrial Proteome ◽  
Encoded Proteins

Abstract The mitochondrial proteome is estimated to contain ∼1100 proteins, the vast majority of which are nuclear-encoded, with only 13 proteins encoded by the mitochondrial genome. The import of these nuclear-encoded proteins into mitochondria was widely believed to be unidirectional, but recent discoveries have revealed that many these ‘mitochondrial’ proteins are exported, and have extra-mitochondrial activities divergent from their mitochondrial function. Surprisingly, three of the exported proteins discovered thus far are mitochondrially encoded and have significantly different extra-mitochondrial roles than those performed within the mitochondrion. In this review, we will detail the wide variety of proteins once thought to only reside within mitochondria, but now known to ‘emigrate’ from mitochondria in order to attain ‘dual citizenship’, present both within mitochondria and elsewhere.

Mitochondrial permeability to chloride ion

1975 ◽  
Vol 228 (1) ◽  
pp. 122-126 ◽  
Author(s):  
MW Weiner
Keyword(s):  
Rat Liver ◽  
Chloride Transport ◽  
Biological Membranes ◽  
Chloride Ion ◽  
The Other ◽  
Beef Heart ◽  
Inner Membrane ◽  
Mitochondrial Permeability ◽  
Mitochondrial Inner Membrane ◽  
Chloride Salts

It is generally accepted that the inner membrane of the mitchondrion is not penetrated by chloride ion, in contrast to other biological membranes which are chloride permeable. In this report mitochondrial permeablity to chloride ion has been reevaluated by the measurement of passive swelling in isotonic chloride-containing solutions in the presence of an uncoupling agent. Under these conditions, mitochondria prepared from rat liver or beef heart show a definite uptake of wide variety of chloride salts. Mitochondrial chloride transport appears to be electrogenic, as is the transmembrane movement of the other halides. Therefore, the mitochondrial inner membrane shares with other biological membranes a definite permeability to this ubiquitous anion.

scholarly journals The potential mechanism of mitochondrial dysfunction in septic cardiomyopathy

2018 ◽  
Vol 46 (6) ◽  
pp. 2157-2169 ◽  
Author(s):  
Pan Pan ◽  
Xiaoting Wang ◽  
Dawei Liu
Keyword(s):  
Mitochondrial Function ◽  
Mitochondrial Gene ◽  
Mitochondrial Fission ◽  
Organ Damage ◽  
Septic Cardiomyopathy ◽  
Mitochondrial Uncoupling ◽  
Heart Research ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Proton Leakage

Septic cardiomyopathy is one of the most serious complications of sepsis or septic shock. Basic and clinical research has studied the mechanism of cardiac dysfunction for more than five decades. It has become clear that myocardial depression is not related to hypoperfusion. As the heart is highly dependent on abundant adenosine triphosphate (ATP) levels to maintain its contraction and diastolic function, impaired mitochondrial function is lethally detrimental to the heart. Research has shown that mitochondria play an important role in organ damage during sepsis. The mitochondria-related mechanisms in septic cardiomyopathy have been discussed in terms of restoring mitochondrial function. Mitochondrial uncoupling proteins located in the mitochondrial inner membrane can promote proton leakage across the mitochondrial inner membrane. Recent studies have demonstrated that proton leakage is the essential regulator of mitochondrial membrane potential and the generation of reactive oxygen species (ROS) and ATP. Other mechanisms involved in septic cardiomyopathy include mitochondrial ROS production and oxidative stress, mitochondria Ca2+ handling, mitochondrial DNA in sepsis, mitochondrial fission and fusion, mitochondrial biogenesis, mitochondrial gene regulation and mitochondria autophagy. This review will provide an overview of recent insights into the factors contributing to septic cardiomyopathy.

Genetic control of meiosis in rice, Oryza sativa L. IV. Cytogenetical analyses of asynaptic mutants

1984 ◽  
Vol 26 (3) ◽  
pp. 264-271 ◽  
Author(s):  
Kunio Kitada ◽  
Takeshi Omura
Keyword(s):  
Oryza Sativa ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Oryza Sativa L ◽  
Recessive Gene ◽  
The Other ◽  
Normal Plant ◽  
Meiotic Stage ◽  
The Mean

One complete asynaptic mutant, MM-19, and two partial ones, MM-4 and MM-16, of Oryza sativa L. induced by N-methyl-N-nitrosourea (MNU) were cytogenetically investigated. No chromosome pairing occurred from zygotene to pachytene and 24 univalents appeared at diakinesis and metaphase 1 in MM-19. On the other hand, a partial lack of chromosome pairing was observed from zygotene to pachytene and various numbers of univalents occurred at metaphase I in MM-4 and MM-16. The mean chiasma frequency per bivalent as well as per cell decreased to different extents in MM-4 and MM-16, and the correlation between both the amount of chromosome pairing from zygotene to pachytene and the chiasma frequency per cell at diakinesis was recognized. Judging from the development of anthers in each meiotic stage, the duration of the stage forming the synizetic knot, at which chromosome pairing took place, was longer in MM-4 and MM-16 than in the normal plant, and was in MM-19 almost as long as in the normal plant. The results of gene analyses indicate that each of the three asynaptic mutants is controlled by a recessive gene and that, at least for MM-4 and MM-16, these genes are located at different loci.Key words: asynaptic, rice, Oryza, chiasma frequency, synizesis.

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