Electron Tomography of Neuronal Mitochondria: Three-Dimensional Structure and Organization of Cristae and Membrane Contacts

Electron Tomography of Neuronal Mitochondria: Three-Dimensional Structure and Organization of... The structure of neuronal mitochondria from chick and rat was examined using electron microscope tomography of chemically fixed tissue embedded in plastic and sliced in ≈500-nm-thick sections. Three-dimensional reconstructions of representative mitochondria were made from single-axis tilt series acquired with an intermediate voltage electron microscope (400 kV). The tilt increment was either 1° or 2° ranging from −60° to +60°. The mitochondrial ultrastructure was similar across species and neuronal regions. The outer and inner membranes were each ≈7 nm thick. The inner boundary membrane was found to lie close to the outer membrane, with a total thickness across both membranes of ≈22 nm. We discovered that the inner membrane invaginates to form cristae only through narrow, tubular openings, which we call crista junctions. Sometimes the cristae remain tubular throughout their length, but often multiple tubular cristae merge to form lamellar compartments. Punctate regions, ≈14 nm in diameter, were observed in which the inner and outer membranes appeared in contact (total thickness of both membranes ≈14 nm). These contact sites are known to a play a key role in the transport of proteins into the mitochondrion. It has been hypothesized that contact sites may be proximal to crista junctions to facilitate transport of proteins destined for the cristae. However, our statistical analyses indicated that contact sites are randomly located with respect to these junctions. In addition, a close association was observed between endoplasmic reticulum membranes and the outer mitochondrial membrane, consistent with the reported mechanism of transport of certain lipids into the mitochondrion. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Structural Biology Elsevier

Electron Tomography of Neuronal Mitochondria: Three-Dimensional Structure and Organization of Cristae and Membrane Contacts

Journal of Structural Biology, Volume 119 (3) – Aug 1, 1997

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Publisher
Elsevier
Copyright
Copyright © 1997 Academic Press
ISSN
1047-8477
eISSN
1095-8657
DOI
10.1006/jsbi.1997.3885
pmid
9245766
Publisher site
See Article on Publisher Site

Abstract

The structure of neuronal mitochondria from chick and rat was examined using electron microscope tomography of chemically fixed tissue embedded in plastic and sliced in ≈500-nm-thick sections. Three-dimensional reconstructions of representative mitochondria were made from single-axis tilt series acquired with an intermediate voltage electron microscope (400 kV). The tilt increment was either 1° or 2° ranging from −60° to +60°. The mitochondrial ultrastructure was similar across species and neuronal regions. The outer and inner membranes were each ≈7 nm thick. The inner boundary membrane was found to lie close to the outer membrane, with a total thickness across both membranes of ≈22 nm. We discovered that the inner membrane invaginates to form cristae only through narrow, tubular openings, which we call crista junctions. Sometimes the cristae remain tubular throughout their length, but often multiple tubular cristae merge to form lamellar compartments. Punctate regions, ≈14 nm in diameter, were observed in which the inner and outer membranes appeared in contact (total thickness of both membranes ≈14 nm). These contact sites are known to a play a key role in the transport of proteins into the mitochondrion. It has been hypothesized that contact sites may be proximal to crista junctions to facilitate transport of proteins destined for the cristae. However, our statistical analyses indicated that contact sites are randomly located with respect to these junctions. In addition, a close association was observed between endoplasmic reticulum membranes and the outer mitochondrial membrane, consistent with the reported mechanism of transport of certain lipids into the mitochondrion.

Journal

Journal of Structural BiologyElsevier

Published: Aug 1, 1997

References

  • Approaches to large-scale structures
    Frank, J.
  • A crucial role of the mitochondrial protein import receptor MOM19 for the biogenesis of mitochondria
    Harkness, T.A.; Nargang, F.E.; van der Klei, I.; Neupert, W.; Lill, R.
  • The mitochondrial protein import apparatus
    Pfanner, N.; Neupert, W.

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