scholarly journals Aim24 and MICOS modulate respiratory function, tafazzin-related cardiolipin modification and mitochondrial architecture

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Max Emanuel Harner ◽  
Ann-Katrin Unger ◽  
Toshiaki Izawa ◽  
Dirk M Walther ◽  
Cagakan Özbalci ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Respiratory Function ◽  
Structure And Function ◽  
Complete Loss ◽  
Mitochondrial Ultrastructure ◽  
Inner Membrane ◽  
Outer Membranes ◽  
Contact Sites ◽  
Inner Membrane Protein ◽  
And Function

Structure and function of mitochondria are intimately linked. In a search for components that participate in building the elaborate architecture of this complex organelle we have identified Aim24, an inner membrane protein. Aim24 interacts with the MICOS complex that is required for the formation of crista junctions and contact sites between inner and outer membranes. Aim24 is necessary for the integrity of the MICOS complex, for normal respiratory growth and mitochondrial ultrastructure. Modification of MICOS subunits Mic12 or Mic26 by His-tags in the absence of Aim24 leads to complete loss of cristae and respiratory complexes. In addition, the level of tafazzin, a cardiolipin transacylase, is drastically reduced and the composition of cardiolipin is modified like in mutants lacking tafazzin. In conclusion, Aim24 by interacting with the MICOS complex plays a key role in mitochondrial architecture, composition and function.

Order-disorder transitions of cytoplasmic N-termini in the mechanisms of P-type ATPases

2020 ◽  
Author(s):  
Khondker Rufaka Hossain ◽  
Daniel Clayton ◽  
Sophia C Goodchild ◽  
Alison Rodger ◽  
Richard James Payne ◽  
...  
Keyword(s):  
Protein Structure ◽  
Membrane Protein ◽  
Structure And Function ◽  
Membrane Protein Structure ◽  
Protein Structure And Function ◽  
Lipid Environment ◽  
Membrane Pumps ◽  
And Function ◽  
P Type

Membrane protein structure and function are modulated via interactions with their lipid environment. This is particularly true for the integral membrane pumps, the P-type ATPases. These ATPases play vital roles...

Nanoscale lipid membrane mimetics in spin-labeling and electron paramagnetic resonance spectroscopy studies of protein structure and function

2017 ◽  
Vol 6 (1) ◽  
pp. 75-92 ◽  
Author(s):  
Elka R. Georgieva
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Protein Structure ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Spin Labeling ◽  
Structure And Function ◽  
Protein Structure And Function ◽  
Paramagnetic Resonance ◽  
And Function ◽  
Electron Paramagnetic

AbstractCellular membranes and associated proteins play critical physiological roles in organisms from all life kingdoms. In many cases, malfunction of biological membranes triggered by changes in the lipid bilayer properties or membrane protein functional abnormalities lead to severe diseases. To understand in detail the processes that govern the life of cells and to control diseases, one of the major tasks in biological sciences is to learn how the membrane proteins function. To do so, a variety of biochemical and biophysical approaches have been used in molecular studies of membrane protein structure and function on the nanoscale. This review focuses on electron paramagnetic resonance with site-directed nitroxide spin-labeling (SDSL EPR), which is a rapidly expanding and powerful technique reporting on the local protein/spin-label dynamics and on large functionally important structural rearrangements. On the other hand, adequate to nanoscale study membrane mimetics have been developed and used in conjunction with SDSL EPR. Primarily, these mimetics include various liposomes, bicelles, and nanodiscs. This review provides a basic description of the EPR methods, continuous-wave and pulse, applied to spin-labeled proteins, and highlights several representative applications of EPR to liposome-, bicelle-, or nanodisc-reconstituted membrane proteins.

scholarly journals Genetic analysis of the role of the conserved inner membrane protein CvpA in EHEC resistance to deoxycholate

2020 ◽  
Author(s):  
Alyson R. Warr ◽  
Rachel T. Giorgio ◽  
Matthew K. Waldor
Keyword(s):  
Stress Response ◽  
Membrane Protein ◽  
Bile Salt ◽  
Cell Envelope ◽  
Enteric Bacteria ◽  
Enteric Pathogens ◽  
Inner Membrane ◽  
Bacterial Phyla ◽  
E Coli ◽  
Inner Membrane Protein

The function of cvpA, a bacterial gene predicted to encode an inner membrane protein, is largely unknown. Early studies in E. coli linked cvpA to Colicin V secretion and recent work revealed that it is required for robust intestinal colonization by diverse enteric pathogens. In enterohemorrhagic E. coli (EHEC), cvpA is required for resistance to the bile salt deoxycholate (DOC). Here, we carried out genome-scale transposon-insertion mutagenesis and spontaneous suppressor analysis to uncover cvpA’s genetic interactions and identify common pathways that rescue the sensitivity of a ΔcvpA EHEC mutant to DOC. These screens demonstrated that mutations predicted to activate the σE-mediated extracytoplasmic stress response bypass the ΔcvpA mutant’s susceptibility to DOC. Consistent with this idea, we found that deletions in rseA and msbB and direct overexpression of rpoE restored DOC resistance to the ΔcvpA mutant. Analysis of the distribution of CvpA homologs revealed that this inner membrane protein is conserved across diverse bacterial phyla, in both enteric and non-enteric bacteria that are not exposed to bile. Together, our findings suggest that CvpA plays a role in cell envelope homeostasis in response to DOC and similar stress stimuli in diverse bacterial species. IMPORTANCE Several enteric pathogens, including Enterohemorrhagic E. coli (EHEC), require CvpA to robustly colonize the intestine. This inner membrane protein is also important for secretion of a colicin and EHEC resistance to the bile salt deoxycholate (DOC), but its function is unknown. Genetic analyses carried out here showed that activation of the σE-mediated extracytoplasmic stress response restored the resistance of a cvpA mutant to DOC, suggesting that CvpA plays a role in cell envelope homeostasis. The conservation of CvpA across diverse bacterial phyla suggests that this membrane protein facilitates cell envelope homeostasis in response to varied cell envelope perturbations.

scholarly journals YieJ (CbrC) Mediates CreBC-Dependent Colicin E2 Tolerance in Escherichia coli

2010 ◽  
Vol 192 (13) ◽  
pp. 3329-3336 ◽  
Author(s):  
S. James L. Cariss ◽  
Chrystala Constantinidou ◽  
Mala D. Patel ◽  
Yuiko Takebayashi ◽  
Jon L. Hobman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Protein ◽  
Microarray Analysis ◽  
Gene Knockout ◽  
Inner Membrane ◽  
Two Component ◽  
Inner Membrane Protein ◽  
Colicin E2 ◽  
K 12

ABSTRACT Colicin E2-tolerant (known as Cet2) Escherichia coli K-12 mutants overproduce an inner membrane protein, CreD, which is believed to cause the Cet2 phenotype. Here, we show that overproduction of CreD in a Cet2 strain results from hyperactivation of the CreBC two-component regulator, but CreD overproduction is not responsible for the Cet2 phenotype. Through microarray analysis and gene knockout and overexpression studies, we show that overexpression of another CreBC-regulated gene, yieJ (also known as cbrC), causes the Cet2 phenotype.

scholarly journals The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria

2012 ◽  
Vol 23 (11) ◽  
pp. 2143-2155 ◽  
Author(s):  
Christian Körner ◽  
Miguel Barrera ◽  
Jovana Dukanovic ◽  
Katharina Eydt ◽  
Max Harner ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Inner Membrane ◽  
Functional Roles ◽  
Architectural Elements ◽  
Contact Sites ◽  
Oligomer Formation ◽  
Terminal Domain ◽  
Moderate Reduction ◽  
Close Proximity ◽  
Inner Membrane Protein

Crista junctions (CJs) are tubular invaginations of the inner membrane of mitochondria that connect the inner boundary with the cristae membrane. These architectural elements are critical for mitochondrial function. The yeast inner membrane protein Fcj1, called mitofilin in mammals, was reported to be preferentially located at CJs and crucial for their formation. Here we investigate the functional roles of individual domains of Fcj1. The most conserved part of Fcj1, the C-terminal domain, is essential for Fcj1 function. In its absence, formation of CJ is strongly impaired and irregular, and stacked cristae are present. This domain interacts with full-length Fcj1, suggesting a role in oligomer formation. It also interacts with Tob55 of the translocase of outer membrane β-barrel proteins (TOB)/sorting and assembly machinery (SAM) complex, which is required for the insertion of β-barrel proteins into the outer membrane. The association of the TOB/SAM complex with contact sites depends on the presence of Fcj1. The biogenesis of β-barrel proteins is not significantly affected in the absence of Fcj1. However, down-regulation of the TOB/SAM complex leads to altered cristae morphology and a moderate reduction in the number of CJs. We propose that the C-terminal domain of Fcj1 is critical for the interaction of Fcj1 with the TOB/SAM complex and thereby for stabilizing CJs in close proximity to the outer membrane. These results assign novel functions to both the C-terminal domain of Fcj1 and the TOB/SAM complex.

Sign in / Sign up

Export Citation Format

Share Document