Mitochondrial distribution and inheritance

Abstract

Mechanisms mediating the inheritance of mitochondria are poorly understood, but recent studies with the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have begun to identify components that facilitate this essential process. These components have been identified through the analysis of conditional yeast mutants that display aberrant mitochondrial distribution at restrictive conditions. The analysis of these mutants has uncovered several novel proteins that are localized either to cytoskeletal structures or to the mitochondria themselves. Many mitochondrial inheritance mutants also show altered mitochondrial morphology and defects in maintenance of the mitochondrial genome. Although some inheritance components and mechanisms appear to function specifically in certain types of cells, other conserved proteins are likely to mediate mitochondrial behavior in all eukaryotic cells.

A mutant for the yeastscERV1 gene displays a new defect in mitochondrial morphology and distribution

“…Initial fluorescence studies identified a drastic change in mitochondrial morphology and distribution at the permissive temperature, in comparison wild-type cells that exhibit the normal peripheral distribution of the mitochondrial network. In contrast to former studies with other mutants that identified giant mitochondria or unusual fusion of membranes (for review, see Bereiter-Hahn and Voth, 1994;Berger and Yaffe, 1996;Herrmann et al, 1998) the pet492 mutant exhibits accumulation of small mitochondrial vesicles that have a tendency to assemble at opposite poles in the cell. Ultrastructural photographs demonstrate that those vesicles are still separated from each other and that in some cases unusual fusion structures of mitochondria are observed.…”

“…Therefore, after the shift to the permissive temperature, the mutant cannot restore respiration because of the missing mitochondrial DNA and the respective gene products for the oxidative chain complexes. The loss of mitochondrial genomes is also found in many other conditional mutants for mitochondrial morphology (Berger and Yaffe, 1996). However, longer incubation of the mutant pet492 leads in addition to a growth defect on glucose complete medium that is also not reversible.…”

“…So far, three main functions and localizations for proteins involved in mitochondrial morphology and distribution have been described: (a) cytosolic proteins that interact with the cytoskeleton and mitochondria (Berger and Yaffe, 1998); (b) proteins of the outer mitochondrial membrane that are attachment sites for cytosolic filaments or microtubules (Sogo and Yaffe, 1994;Yaffe et al, 1996); and (c) cytosolic and matrix proteins that are involved in the biosynthesis of products essential for membrane biogenesis, e.g. fatty acid synthesis (for review, see Berger and Yaffe, 1996;Schneiter and Kohlwein, 1997). The present data suggest that scErv1p may belong to the third class of those proteins, and thereby may be involved in the biosynthesis or protection of intact mitochondrial membranes.…”

“…The complex influence of the scERV1 gene on mitochondrial biogenesis and the vegetative growth prompted us to investigate the influence of this gene on morphology and distribution of mitochondria in the conditional mutant. In recent studies it has been shown that mitochondrial morphology, distribution, fusion and fission are complex processes genetically controlled by a larger number of special nuclear genes, most of which have been identified by appropriate conditional mutants (for review, see Berger and Yaffe, 1996;Schneiter and Kohlwein, 1997;.…”

Prohibitin Family Members Interact Genetically with Mitochondrial Inheritance Components in Saccharomyces cerevisiae

“…In budding yeast, factors specifically required for mitochondrial inheritance have been identified and characterized through the analysis of conditional mutants (7,25). Three distinct proteins of the mitochondrial outer membrane, Mdm10p, Mmm1p, and Mdm12p, have been found to constitute one class of mitochondrial inheritance factors.…”