scholarly journals Cortical tethering of mitochondria by the anchor protein Mcp5 enables uniparental inheritance

2019 ◽  
Vol 218 (11) ◽  
pp. 3560-3571 ◽  
Author(s):  
Leeba Ann Chacko ◽  
Kritika Mehta ◽  
Vaishnavi Ananthanarayanan
Keyword(s):  
Mitochondrial Dna ◽  
High Resolution ◽  
Coiled Coil ◽  
The Other ◽  
Uniparental Inheritance ◽  
Zygote Formation ◽  
Mitochondrial Inheritance ◽  
Anchor Protein ◽  
Distinct Mechanism ◽  
Coiled Coil Domain

During sexual reproduction in eukaryotes, processes such as active degradation and dilution of paternal mitochondria ensure maternal mitochondrial inheritance. In the isogamous organism fission yeast, we employed high-resolution fluorescence microscopy to visualize mitochondrial inheritance during meiosis by differentially labeling mitochondria of the two parental cells. Remarkably, mitochondria, and thereby mitochondrial DNA from the parental cells, did not mix upon zygote formation but remained segregated at the poles by attaching to clusters of the anchor protein Mcp5 via its coiled-coil domain. We observed that this tethering of parental mitochondria to the poles results in uniparental inheritance of mitochondria, wherein two of the four spores formed subsequently contained mitochondria from one parent and the other spores contained mitochondria from the other parent. Further, the presence of dynein on an Mcp5 cluster precluded the attachment of mitochondria to the same cluster. Taken together, we reveal a distinct mechanism that achieves uniparental inheritance by segregation of parental mitochondria.

scholarly journals Cortical tethering of mitochondria by the dynein anchor Mcp5 enables uniparental mitochondrial inheritance during fission yeast meiosis

2019 ◽  
Author(s):  
Kritika Mehta ◽  
Vaishnavi Ananthanarayanan
Keyword(s):  
Mitochondrial Dna ◽  
Fission Yeast ◽  
Coiled Coil ◽  
The Other ◽  
Uniparental Inheritance ◽  
Zygote Formation ◽  
Mitochondrial Inheritance ◽  
Distinct Mechanism ◽  
Coiled Coil Domain ◽  
Yeast Meiosis

SummaryDuring sexual reproduction in eukaryotes, processes such as active degradation and dilution of paternal mitochondria ensure maternal mitochondrial inheritance. In the isogamous organism fission yeast, we employed high-resolution fluorescence microscopy to visualize mitochondrial inheritance during meiosis by differentially labeling mitochondria of the two parental cells. Remarkably, mitochondria, and thereby, mitochondrial DNA from the parental cells did not mix upon zygote formation, but remained segregated at the poles by attaching to clusters of the dynein anchor Mcp5 via its coiled-coil domain. We observed that this tethering of parental mitochondria to the poles results in uniparental inheritance of mitochondria, wherein two of the four spores formed subsequently contained mitochondria from one parent and the other spores, mitochondria from the other parent. Further, the presence of dynein on an Mcp5 cluster precluded the attachment of mitochondria to the same cluster. Taken together, we reveal a distinct mechanism that achieves uniparental inheritance by segregation of parental mitochondria.

scholarly journals Rapid, Selective Digestion of Mitochondrial DNA in Accordance With the matA Hierarchy of Multiallelic Mating Types in the Mitochondrial Inheritance of Physarum polycephalum

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 963-975 ◽  
Author(s):  
Y Moriyama ◽  
S Kawano
Keyword(s):  
Mitochondrial Dna ◽  
Physarum Polycephalum ◽  
Nuclear Fusion ◽  
The Other ◽  
Pcr Analysis ◽  
Uniparental Inheritance ◽  
Mating Types ◽  
Mitochondrial Inheritance ◽  
Biparental Inheritance ◽  
Mitochondrial Nucleoids

Abstract Although mitochondria are inherited uniparentally in nearly all eukaryotes, the mechanism for this is unclear. When zygotes of the isogamous protist Physarum polycephalum were stained with DAPI, the fluorescence of mtDNA in half of the mitochondria decreased simultaneously to give small spots and then disappeared completely ∼1.5 hr after nuclear fusion, while the other mitochondrial nucleoids and all of the mitochondrial sheaths remained unchanged. PCR analysis of single zygote cells confirmed that the loss was limited to mtDNA from one parent. The vacant mitochondrial sheaths were gradually eliminated by 60 hr after mating. Using six mating types, the transmission patterns of mtDNA were examined in all possible crosses. In 39 of 60 crosses, strict uniparental inheritance was confirmed in accordance with a hierarchy of relative sexuality. In the other crosses, however, mtDNA from both parents was transmitted to plasmodia. The ratio of parental mtDNA was estimated to be from 1:1 to 1:10-4. Nevertheless, the matA hierarchy was followed. In these crosses, the mtDNA was incompletely digested, and mtDNA replicated during subsequent plasmodial development. We conclude that the rapid, selective digestion of mtDNA promotes the uniparental inheritance of mitochondria; when this fails, biparental inheritance occurs.

scholarly journals Uniparental inheritance and replacement of mitochondrial DNA in Neurospora tetrasperma.

Genetics ◽  
1993 ◽  
Vol 134 (4) ◽  
pp. 1063-1075
Author(s):  
S B Lee ◽  
J W Taylor
Keyword(s):  
Mitochondrial Dna ◽  
Uniparental Inheritance ◽  
Mitochondrial Inheritance ◽  
Reproductive Structure ◽  
Hyphal Fusion ◽  
Heterokaryon Incompatibility ◽  
Reciprocal Interactions ◽  
Mtdna Inheritance ◽  
Length Polymorphisms ◽  
Neurospora Tetrasperma

Abstract This study tested mechanisms proposed for maternal uniparental mitochondrial inheritance in Neurospora: (1) exclusion of conidial mitochondria by the specialized female reproductive structure, trichogyne, due to mating locus heterokaryon incompatibility and (2) mitochondrial input bias favoring the larger trichogyne over the smaller conidium. These mechanisms were tested by determining the modes of mitochondrial DNA (mtDNA) inheritance and transmission in the absence of mating locus heterokaryon incompatibility following crosses of uninucleate strains of Neurospora tetrasperma with trichogyne (trichogyne inoculated by conidia) and without trichogyne (hyphal fusion). Maternal uniparental mitochondrial inheritance was observed in 136 single ascospore progeny following both mating with and without trichogyne using mtDNA restriction fragment length polymorphisms to distinguish parental types. This suggests that maternal mitochondrial inheritance following hyphal fusions is due to some mechanism other than those that implicate the trichogyne. Following hyphal fusion, mutually exclusive nuclear migration permitted investigation of reciprocal interactions. Regardless of which strain accepted nuclei following seven replicate hyphal fusion matings, acceptor mtDNA was the only type detected in 34 hyphal plug and tip samples taken from the contact and acceptor zones. No intracellular mtDNA mixtures were detected. Surprisingly, 3 days following hyphal fusion, acceptor mtDNA replaced donor mtDNA throughout the entire colony. To our knowledge, this is the first report of complete mitochondrial replacement during mating in a filamentous fungus.

scholarly journals Evidence for mitochondrial DNA polymorphism and uniparental inheritance in the cellular slime mold Polysphondylium pallidum: effect of intraspecies mating on mitochondrial DNA transmission.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 607-613
Author(s):  
M Mirfakhrai ◽  
Y Tanaka ◽  
K Yanagisawa
Keyword(s):  
Mitochondrial Dna ◽  
Slime Mold ◽  
Cellular Slime Mold ◽  
Uniparental Inheritance ◽  
Mating Types ◽  
Mitochondrial Inheritance ◽  
Mitochondrial Dna Polymorphism ◽  
Polysphondylium Pallidum ◽  
Length Polymorphisms ◽  
Cellular Slime

Abstract Restriction fragment length polymorphisms (RFLPs) were used as markers to monitor mitochondrial inheritance in the cellular slime mold, Polysphondylium pallidum. When two opposite mating types (mat1 and mat2) of closely related strains were crossed, all the haploid progeny regardless of mating type inherited their mitochondrial DNA from the mat2 parent only. When opposite mating types from more distantly related strains were crossed, most of the progeny also inherited their mitochondrial DNA from the mat2 parent, but some inherited their mitochondrial DNA from the mat1 parent. In both cases however, the transmission of mitochondrial DNA was uniparental, since in every individual progeny only one type of mitochondrial DNA exists. Moreover, in crosses involving more distantly related strains all the progeny of a single macrocyst were shown to contain the same type of mitochondrial DNA. These findings are discussed in regard to mechanisms of transmission and the possible involvement of nuclear genes in the control of transmission of mitochondrial DNA in Polysphondylium.

scholarly journals Prezygotic and Postzygotic Control of Uniparental Mitochondrial DNA Inheritance in Cryptococcus neoformans

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Rachana Gyawali ◽  
Xiaorong Lin
Keyword(s):  
Mitochondrial Dna ◽  
Cryptococcus Neoformans ◽  
Cell Fusion ◽  
Uniparental Inheritance ◽  
Mitochondrial Inheritance ◽  
Inheritance Pattern ◽  
Content Type ◽  
Mtdna Inheritance ◽  
Higher Eukaryotes ◽  
Eukaryotic Microbe

ABSTRACT Uniparental inheritance of mitochondrial DNA is pervasive in nonisogamic higher eukaryotes during sexual reproduction, and postzygotic and/or prezygotic factors are shown to be important in ensuring such an inheritance pattern. Although the fungus Cryptococcus neoformans undergoes sexual production with isogamic partners of opposite mating types a and α, most progeny derived from such mating events inherit the mitochondrial DNA (mtDNA) from the a parent. The homeodomain protein complex Sxi1α/Sxi2a, formed in the zygote after a-α cell fusion, was previously shown to play a role in this uniparental mtDNA inheritance. Here, we defined the timing of the establishment of the mtDNA inheritance pattern during the mating process and demonstrated a critical role in determining the mtDNA inheritance pattern by a prezygotic factor, Mat2. Mat2 is the key transcription factor that governs the pheromone sensing and response pathway, and it is critical for the early mating events that lead to cell fusion and zygote formation. We show that Mat2 governs mtDNA inheritance independently of the postzygotic factors Sxi1α/Sxi2a, and the cooperation between these prezygotic and postzygotic factors helps to achieve stricter uniparental mitochondrial inheritance in this eukaryotic microbe. IMPORTANCE Mitochondrial DNA is inherited uniparentally from the maternal parent in the majority of eukaryotes. Studies done on higher eukaryotes such as mammals have shown that the transmission of parental mitochondrial DNA is controlled at both the prefertilization and postfertilization stages to achieve strict uniparental inheritance. However, the molecular mechanisms underlying such uniparental mitochondrial inheritance have been investigated in detail mostly in anisogamic multicellular eukaryotes. Here, we show that in a simple isogamic microbe, Cryptococcus neoformans, the mitochondrial inheritance is controlled at the prezygotic level as well as the postzygotic level by regulators that are critical for sexual development. Furthermore, the cooperation between these two levels of control ensures stricter uniparental mitochondrial inheritance, echoing what has been observed in higher eukaryotes. Thus, the investigation of uniparental mitochondrial inheritance in this eukaryotic microbe could help advance our understanding of the convergent evolution of this widespread phenomenon in the eukaryotic domain.

scholarly journals Direct membrane binding and self-interaction contribute to Mmr1 function in mitochondrial inheritance

2018 ◽  
Vol 29 (19) ◽  
pp. 2346-2357 ◽  
Author(s):  
WeiTing Chen ◽  
Holly A. Ping ◽  
Laura L. Lackner
Keyword(s):  
Structure Function ◽  
Membrane Binding ◽  
Coiled Coil ◽  
Mitochondrial Inheritance ◽  
Binding Assays ◽  
Membrane Interaction ◽  
Coiled Coil Domain ◽  
Necessary And Sufficient

Mitochondrial transport and anchoring mechanisms work in concert to position mitochondria to meet cellular needs. In yeast, Mmr1 functions as a mitochondrial adaptor for Myo2 to facilitate actin-based transport of mitochondria to the bud. Posttransport, Mmr1 is proposed to anchor mitochondria at the bud tip. Although both functions require an interaction between Mmr1 and mitochondria, the molecular basis of the Mmr1–mitochondria interaction is poorly understood. Our in vitro phospholipid binding assays indicate Mmr1 can directly interact with phospholipid membranes. Through structure–function studies we identified an unpredicted membrane-binding domain composed of amino acids 76–195 that is both necessary and sufficient for Mmr1 to interact with mitochondria in vivo and liposomes in vitro. In addition, our structure–function analyses indicate that the coiled-coil domain of Mmr1 is necessary and sufficient for Mmr1 self-interaction and facilitates the polarized localization of the protein. Disrupting either the Mmr1–membrane interaction or Mmr1 self-interaction leads to defects in mitochondrial inheritance. Therefore, direct membrane binding and self-interaction are necessary for Mmr1 function in mitochondrial inheritance and are utilized as a means to spatially and temporally regulate mitochondrial positioning.

Computer-Controlled Hrem Alignment Using Automated Diffractogram Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 532-533
Author(s):  
G.Y. Fan ◽  
O.L. Krivanek
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
The Other ◽  
Full Information ◽  
Resolution Electron ◽  
Skilled Operator ◽  
Automatic Alignment ◽  
High Resolution Electron Microscope ◽  
Computer Controlled ◽  
Recorded Image

Full alignment of a high resolution electron microscope (HREM) requires five parameters to be optimized: the illumination angle (beam tilt) x and y, defocus, and astigmatism magnitude and orientation. Because neither voltage nor current centering lead to the correct illumination angle, all the adjustments must be done on the basis of observing contrast changes in a recorded image. The full alignment can be carried out by a computer which is connected to a suitable image pick-up device and is able to control the microscope, sometimes with greater precision and speed than even a skilled operator can achieve. Two approaches to computer-controlled (automatic) alignment have been investigated. The first is based on measuring the dependence of the overall contrast in the image of a thin amorphous specimen on the relevant parameters, the other on measuring the image shift. Here we report on our progress in developing a new method, which makes use of the full information contained in a computed diffractogram.

TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum

2019 ◽  
Vol 476 (21) ◽  
pp. 3241-3260
Author(s):  
Sindhu Wisesa ◽  
Yasunori Yamamoto ◽  
Toshiaki Sakisaka
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Transmembrane Domains ◽  
Domain Family ◽  
Coiled Coil Domain ◽  
U2os Cells ◽  
Er Membrane

The tubular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions. Two classes of the conserved ER membrane proteins, atlastins and lunapark, have been shown to reside at the three-way junctions so far and be involved in the generation and stabilization of the three-way junctions. In this study, we report TMCC3 (transmembrane and coiled-coil domain family 3), a member of the TEX28 family, as another ER membrane protein that resides at the three-way junctions in mammalian cells. When the TEX28 family members were transfected into U2OS cells, TMCC3 specifically localized at the three-way junctions in the peripheral ER. TMCC3 bound to atlastins through the C-terminal transmembrane domains. A TMCC3 mutant lacking the N-terminal coiled-coil domain abolished localization to the three-way junctions, suggesting that TMCC3 localized independently of binding to atlastins. TMCC3 knockdown caused a decrease in the number of three-way junctions and expansion of ER sheets, leading to a reduction of the tubular ER network in U2OS cells. The TMCC3 knockdown phenotype was partially rescued by the overexpression of atlastin-2, suggesting that TMCC3 knockdown would decrease the activity of atlastins. These results indicate that TMCC3 localizes at the three-way junctions for the proper tubular ER network.

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