A crucial role of the mitochondrial protein import receptor MOM19 for the biogenesis of mitochondria

• Published in: The Journal of cell biology Vol. 124; no. 5; pp. 637 - 648
• Main Authors: Harkness, T.A.A, Nargang, F.E, Klei, I. van der, Neupert, W, Lill, R
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.03.1994; The Rockefeller University Press
• Subjects: Antibodies; Biological and medical sciences; Cell growth; Cells; Cellular biology; CHIMIORECEPTEUR; Chromosomes; Cytochromes; Cytochromes - biosynthesis; Diverse techniques; Fundamental and applied biological sciences. Psychology; Fungal Proteins - biosynthesis; Fungal Proteins - metabolism; Genes, Fungal; Imports; Kinetics; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; Membrane Proteins - metabolism; Membrane Transport Proteins; Membranes; METABOLISME DES PROTEINES; METABOLISMO PROTEICO; Microscopy, Electron; Mitochondria; Mitochondria - metabolism; Mitochondria - ultrastructure; MITOCHONDRIE; MITOCONDRIA; Molecular and cellular biology; MUTANT; MUTANTES; Mutation; Neurons; NEUROSPORA; Neurospora crassa; Neurospora crassa - genetics; Neurospora crassa - growth & development; Neurospora crassa - metabolism; Point Mutation; Protein precursors; PROTEINAS; PROTEINE; Proteins; QUIMIORECEPTORS; Receptors; Receptors, Cell Surface; Receptors, Cytoplasmic and Nuclear - biosynthesis; Receptors, Cytoplasmic and Nuclear - genetics; Receptors, Cytoplasmic and Nuclear - metabolism; Repetitive Sequences, Nucleic Acid; Fungi; Proteins; Mitochondria; Development; Ascomycetes; Neurospora crassa; Mutation; Technique; Biological receptor; Thallophyta
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.124.5.637

The novel genetic method of "sheltered RIP" (repeat induced point mutation) was used to generate a Neurospora crassa mutant in which MOM19, a component of the protein import machinery of the mitochondrial outer membrane, can be depleted. Deficiency in MOM19 resulted in a severe growth defect, but the cells remained viable. The number of mitochondrial profiles was not grossly changed, but mutant mitochondria were highly deficient in cristae membranes, cytochromes, and protein synthesis activity. Protein import into isolated mutant mitochondria was decreased by factors of 6 to 30 for most proteins from all suborganellar compartments. Proteins like the ADP/ATP carrier, MOM19, and cytochrome c, whose import into wild-type mitochondria occurs independently of MOM19 became imported normally showing that the reduced import activities are solely caused by a lack of MOM19. Depletion of MOM19 reveals a close functional relationship between MOM19 and MOM22, since loss of MOM19 led to decreased levels of MOM22 and reduced protein import through MOM22. Furthermore, MOM72 does not function as a general backup receptor for MOM19 suggesting that these two proteins have distinct precursor specificities. These findings demonstrate that the import receptor MOM19 fulfills an important role in the biogenesis of mitochondria and that it is essential for the formation of mitochondria competent in respiration and phosphorylation