scholarly journals Multispan mitochondrial outer membrane protein Ugo1 follows a unique Mim1-dependent import pathway

2011 ◽  
Vol 194 (3) ◽  
pp. 397-405 ◽  
Author(s):  
Dražen Papić ◽  
Katrin Krumpe ◽  
Jovana Dukanovic ◽  
Kai S. Dimmer ◽  
Doron Rapaport
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Gel Electrophoresis ◽  
Mitochondrial Outer Membrane ◽  
Yeast Mitochondria ◽  
Membrane Complex ◽  
Native Gel ◽  
Insertion Process ◽  
Import Receptor

The mitochondrial outer membrane (MOM) harbors several multispan proteins that execute various functions. Despite their importance, the mechanisms by which these proteins are recognized and inserted into the outer membrane remain largely unclear. In this paper, we address this issue using yeast mitochondria and the multispan protein Ugo1. Using a specific insertion assay and analysis by native gel electrophoresis, we show that the import receptor Tom70, but not its partner Tom20, is involved in the initial recognition of the Ugo1 precursor. Surprisingly, the import pore formed by the translocase of the outer membrane complex appears not to be required for the insertion process. Conversely, the multifunctional outer membrane protein mitochondrial import 1 (Mim1) plays a central role in mediating the insertion of Ugo1. Collectively, these results suggest that Ugo1 is inserted into the MOM by a novel pathway in which Tom70 and Mim1 contribute to the efficiency and selectivity of the process.

scholarly journals Mutations in Fis1 disrupt orderly disposal of defective mitochondria

2014 ◽  
Vol 25 (1) ◽  
pp. 145-159 ◽  
Author(s):  
Qinfang Shen ◽  
Koji Yamano ◽  
Brian P. Head ◽  
Sumihiro Kawajiri ◽  
Jesmine T. M. Cheung ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Couple Stress ◽  
Mitochondrial Fission ◽  
Mitochondrial Outer Membrane ◽  
Related Protein ◽  
Degradation Processes ◽  
Mitochondrial Toxins

Mitochondrial fission is mediated by the dynamin-related protein Drp1 in metazoans. Drp1 is recruited from the cytosol to mitochondria by the mitochondrial outer membrane protein Mff. A second mitochondrial outer membrane protein, named Fis1, was previously proposed as recruitment factor, but Fis1−/− cells have mild or no mitochondrial fission defects. Here we show that Fis1 is nevertheless part of the mitochondrial fission complex in metazoan cells. During the fission cycle, Drp1 first binds to Mff on the surface of mitochondria, followed by entry into a complex that includes Fis1 and endoplasmic reticulum (ER) proteins at the ER–mitochondrial interface. Mutations in Fis1 do not normally affect fission, but they can disrupt downstream degradation events when specific mitochondrial toxins are used to induce fission. The disruptions caused by mutations in Fis1 lead to an accumulation of large LC3 aggregates. We conclude that Fis1 can act in sequence with Mff at the ER–mitochondrial interface to couple stress-induced mitochondrial fission with downstream degradation processes.

scholarly journals Super-Resolution Fluorescence Microscopy Reveals Clustering Behaviour of Chlamydia pneumoniae’s Major Outer Membrane Protein

Biology ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 344
Author(s):  
Amy E. Danson ◽  
Alex McStea ◽  
Lin Wang ◽  
Alice Y. Pollitt ◽  
Marisa L. Martin-Fernandez ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Chlamydia Pneumoniae ◽  
Inflammatory Diseases ◽  
Super Resolution ◽  
Homology Model ◽  
Major Outer Membrane Protein ◽  
Membrane Complex ◽  
Antimicrobial Studies

Chlamydia pneumoniae is a Gram-negative bacterium responsible for a number of human respiratory diseases and linked to some chronic inflammatory diseases. The major outer membrane protein (MOMP) of Chlamydia is a conserved immunologically dominant protein located in the outer membrane, which, together with its surface exposure and abundance, has led to MOMP being the main focus for vaccine and antimicrobial studies in recent decades. MOMP has a major role in the chlamydial outer membrane complex through the formation of intermolecular disulphide bonds, although the exact interactions formed are currently unknown. Here, it is proposed that due to the large number of cysteines available for disulphide bonding, interactions occur between cysteine-rich pockets as opposed to individual residues. Such pockets were identified using a MOMP homology model with a supporting low-resolution (~4 Å) crystal structure. The localisation of MOMP in the E. coli membrane was assessed using direct stochastic optical reconstruction microscopy (dSTORM), which showed a decrease in membrane clustering with cysteine-rich regions containing two mutations. These results indicate that disulphide bond formation was not disrupted by single mutants located in the cysteine-dense regions and was instead compensated by neighbouring cysteines within the pocket in support of this cysteine-rich pocket hypothesis.

scholarly journals Flavin nucleotides act as electron shuttles mediating reduction of the [2Fe-2S] clusters in mitochondrial outer membrane protein mitoNEET

2017 ◽  
Vol 102 ◽  
pp. 240-247 ◽  
Author(s):  
Aaron P. Landry ◽  
Yiming Wang ◽  
Zishuo Cheng ◽  
Robert B. Crochet ◽  
Yong-Hwan Lee ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Mitochondrial Outer Membrane ◽  
Electron Shuttles
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