scholarly journals Degradation of mitochondrial alternative oxidase in the appendices of Arum maculatum

2020 ◽  
Vol 477 (17) ◽  
pp. 3417-3431
Author(s):  
Kikukatsu Ito ◽  
Takafumi Ogata ◽  
Takanari Seito ◽  
Yui Umekawa ◽  
Yusuke Kakizaki ◽  
...  

Cyanide-resistant alternative oxidase (AOX) is a nuclear-encoded quinol oxidase located in the inner mitochondrial membrane. Although the quality control of AOX proteins is expected to have a role in elevated respiration in mitochondria, it remains unclear whether thermogenic plants possess molecular mechanisms for the mitochondrial degradation of AOX. To better understand the mechanism of AOX turnover in mitochondria, we performed a series of in organello AOX degradation assays using mitochondria from various stages of the appendices of Arum maculatum. Our analyses clearly indicated that AOX proteins at certain stages in the appendices are degraded at 30°C, which is close to the maximum appendix temperature observed during thermogenesis. Interestingly, such temperature-dependent protease activities were specifically inhibited by E-64, a cysteine protease inhibitor. Moreover, purification and subsequent nano LC–MS/MS analyses of E-64-sensitive and DCG-04-labeled active mitochondrial protease revealed an ∼30 kDa protein with an identical partial peptide sequence to the cysteine protease 1-like protein from Phoenix dactylifera. Our data collectively suggest that AOX is a potential target for temperature-dependent E-64-sensitive cysteine protease in the appendices of A. maculatum. A possible retrograde signalling cascade mediated by specific degradation of AOX proteins and its physiological significance are discussed.

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 388
Author(s):  
Hương Giang Lê ◽  
A-Jeong Ham ◽  
Jung-Mi Kang ◽  
Tuấn Cường Võ ◽  
Haung Naw ◽  
...  

Naegleria fowleri is a free-living amoeba that is ubiquitous in diverse natural environments. It causes a fatal brain infection in humans known as primary amoebic meningoencephalitis. Despite the medical importance of the parasitic disease, there is a great lack of knowledge about the biology and pathogenicity of N. fowleri. In this study, we identified and characterized a novel cysteine protease inhibitor of N. fowleri (NfCPI). NfCPI is a typical cysteine protease inhibitor belonging to the cystatin family with a Gln-Val-Val-Ala-Gly (QVVAG) motif, a characteristic motif conserved in the cystatin family of proteins. Bacterially expressed recombinant NfCPI has a dimeric structure and exhibits inhibitory activity against several cysteine proteases including cathespin Bs of N. fowleri at a broad range of pH values. Expression profiles of nfcpi revealed that the gene was highly expressed during encystation and cyst of the amoeba. Western blot and immunofluorescence assays also support its high level of expression in cysts. These findings collectively suggest that NfCPI may play a critical role in encystation or cyst formation of N. fowleri by regulating cysteine proteases that may mediate encystation or mature cyst formation of the amoeba. More comprehensive studies to investigate the roles of NfCPI in encystation and its target proteases are necessary to elucidate the regulatory mechanism and the biological significance of NfCPI.


2005 ◽  
Vol 96 (1) ◽  
pp. 137-144 ◽  
Author(s):  
A.M. Zagariya ◽  
R. Bhat ◽  
E. Zhabotynsky ◽  
G. Chari ◽  
S. Navale ◽  
...  

2017 ◽  
Vol 26 (4) ◽  
pp. 563-569 ◽  
Author(s):  
Bartłomiej Stańczykiewicz ◽  
Marta Jakubik-Witkowska ◽  
Antoni Polanowski ◽  
Tadeusz Trziszka ◽  
Joanna Rymaszewska

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Bui T. T. Nga ◽  
Yuki Takeshita ◽  
Misa Yamamoto ◽  
Yoshimi Yamamoto

Mouse cytotoxic T-lymphocyte antigen-2α (CTLA-2α), Drosophila CTLA-2-like protein (crammer), and Bombyx cysteine protease inhibitor (BCPI) belong to a novel family of cysteine protease inhibitors (I29). Their inhibitory mechanisms were studied comparatively. CTLA-2α contains a cysteine residue (C75), which is essential for its inhibitory potency. The CTLA-2α monomer was converted to a disulfide-bonded dimer in vitro and in vivo. The dimer was fully inhibitory, but the monomer, which possessed a free thiol residue, was not. A disulfide-bonded CTLA-2α/cathepsin L complex was isolated, and a cathepsin L subunit with a molecular weight of 24,000 was identified as the interactive enzyme protein. Crammer also contains a cysteine residue (C72). Both dimeric and monomeric forms of crammer were inhibitory. A crammer mutant with Cys72 to alanine (C72A) was fully inhibitory, while the replacement of Gly73 with alanine (G73A) caused a significant loss in inhibitory potency, which suggests a different inhibition mechanism from CTLA-2α. BCPI does not contain cysteine residue. C-terminal region (L77-R80) of BCPI was essential for its inhibitory potency. CTLA-2α was inhibitory in the acidic pH condition but stabilized cathepsin L under neutral pH conditions. The different inhibition mechanisms and functional considerations of these inhibitors are discussed.


2017 ◽  
Vol 41 (4) ◽  
pp. 1049-1058
Author(s):  
Manal Salah El-Din Mahmoud ◽  
Ayman Nabil Ibrahim ◽  
Abeer Fathy Badawy ◽  
Nourhan Mohamed Abdelmoniem

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