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Key J, Gispert S, Auburger G. Knockout Mouse Studies Show That Mitochondrial CLPP Peptidase and CLPX Unfoldase Act in Matrix Condensates near IMM, as Fast Stress Response in Protein Assemblies for Transcript Processing, Translation, and Heme Production. Genes (Basel) 2024; 15:694. [PMID: 38927630 PMCID: PMC11202940 DOI: 10.3390/genes15060694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
LONP1 is the principal AAA+ unfoldase and bulk protease in the mitochondrial matrix, so its deletion causes embryonic lethality. The AAA+ unfoldase CLPX and the peptidase CLPP also act in the matrix, especially during stress periods, but their substrates are poorly defined. Mammalian CLPP deletion triggers infertility, deafness, growth retardation, and cGAS-STING-activated cytosolic innate immunity. CLPX mutations impair heme biosynthesis and heavy metal homeostasis. CLPP and CLPX are conserved from bacteria to humans, despite their secondary role in proteolysis. Based on recent proteomic-metabolomic evidence from knockout mice and patient cells, we propose that CLPP acts on phase-separated ribonucleoprotein granules and CLPX on multi-enzyme condensates as first-aid systems near the inner mitochondrial membrane. Trimming within assemblies, CLPP rescues stalled processes in mitoribosomes, mitochondrial RNA granules and nucleoids, and the D-foci-mediated degradation of toxic double-stranded mtRNA/mtDNA. Unfolding multi-enzyme condensates, CLPX maximizes PLP-dependent delta-transamination and rescues malformed nascent peptides. Overall, their actions occur in granules with multivalent or hydrophobic interactions, separated from the aqueous phase. Thus, the role of CLPXP in the matrix is compartment-selective, as other mitochondrial peptidases: MPPs at precursor import pores, m-AAA and i-AAA at either IMM face, PARL within the IMM, and OMA1/HTRA2 in the intermembrane space.
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Affiliation(s)
| | | | - Georg Auburger
- Experimental Neurology, Clinic of Neurology, University Hospital, Goethe University Frankfurt, Heinrich Hoffmann Str. 7, 60590 Frankfurt am Main, Germany; (J.K.); (S.G.)
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Mizrahi R, Ostersetzer-Biran O. Mitochondrial RNA Helicases: Key Players in the Regulation of Plant Organellar RNA Splicing and Gene Expression. Int J Mol Sci 2024; 25:5502. [PMID: 38791540 PMCID: PMC11122041 DOI: 10.3390/ijms25105502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/06/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Mitochondrial genomes of land plants are large and exhibit a complex mode of gene organization and expression, particularly at the post-transcriptional level. The primary organellar transcripts in plants undergo extensive maturation steps, including endo- and/or exo-nucleolytic cleavage, RNA-base modifications (mostly C-to-U deaminations) and both 'cis'- and 'trans'-splicing events. These essential processing steps rely on the activities of a large set of nuclear-encoded factors. RNA helicases serve as key players in RNA metabolism, participating in the regulation of transcription, mRNA processing and translation. They unwind RNA secondary structures and facilitate the formation of ribonucleoprotein complexes crucial for various stages of gene expression. Furthermore, RNA helicases are involved in RNA metabolism by modulating pre-mRNA maturation, transport and degradation processes. These enzymes are, therefore, pivotal in RNA quality-control mechanisms, ensuring the fidelity and efficiency of RNA processing and turnover in plant mitochondria. This review summarizes the significant roles played by helicases in regulating the highly dynamic processes of mitochondrial transcription, RNA processing and translation in plants. We further discuss recent advancements in understanding how dysregulation of mitochondrial RNA helicases affects the splicing of organellar genes, leading to respiratory dysfunctions, and consequently, altered growth, development and physiology of land plants.
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Affiliation(s)
| | - Oren Ostersetzer-Biran
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus—Givat Ram, Jerusalem 9190401, Israel
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Shiryaev SA, Cieplak P, Cheltsov A, Liddington RC, Terskikh AV. Dual function of Zika virus NS2B-NS3 protease. PLoS Pathog 2023; 19:e1011795. [PMID: 38011215 PMCID: PMC10723727 DOI: 10.1371/journal.ppat.1011795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/15/2023] [Accepted: 11/02/2023] [Indexed: 11/29/2023] Open
Abstract
Zika virus (ZIKV) serine protease, indispensable for viral polyprotein processing and replication, is composed of the membrane-anchored NS2B polypeptide and the N-terminal domain of the NS3 polypeptide (NS3pro). The C-terminal domain of the NS3 polypeptide (NS3hel) is necessary for helicase activity and contains an ATP-binding site. We discovered that ZIKV NS2B-NS3pro binds single-stranded RNA with a Kd of ~0.3 μM, suggesting a novel function. We tested various structural modifications of NS2B-NS3pro and observed that constructs stabilized in the recently discovered "super-open" conformation do not bind RNA. Likewise, stabilizing NS2B-NS3pro in the "closed" (proteolytically active) conformation using substrate inhibitors abolished RNA binding. We posit that RNA binding occurs when ZIKV NS2B-NS3pro adopts the "open" conformation, which we modeled using highly homologous dengue NS2B-NS3pro crystallized in the open conformation. We identified two positively charged fork-like structures present only in the open conformation of NS3pro. These forks are conserved across Flaviviridae family and could be aligned with the positively charged grove on NS3hel, providing a contiguous binding surface for the negative RNA strand exiting helicase. We propose a "reverse inchworm" model for a tightly intertwined NS2B-NS3 helicase-protease machinery, which suggests that NS2B-NS3pro cycles between open and super-open conformations to bind and release RNA enabling long-range NS3hel processivity. The transition to the closed conformation, likely induced by the substrate, enables the classical protease activity of NS2B-NS3pro.
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Affiliation(s)
- Sergey A. Shiryaev
- Sanford-Burnham-Prebys Medical Discovery Institute, Infectious and Inflammatory Disease Center, La Jolla, California, United States of America
| | - Piotr Cieplak
- Sanford-Burnham-Prebys Medical Discovery Institute, Infectious and Inflammatory Disease Center, La Jolla, California, United States of America
| | - Anton Cheltsov
- Q-mol LLC, San Diego, California, United States of America
| | - Robert C. Liddington
- Sanford-Burnham-Prebys Medical Discovery Institute, Infectious and Inflammatory Disease Center, La Jolla, California, United States of America
| | - Alexey V. Terskikh
- Sanford-Burnham-Prebys Medical Discovery Institute, Infectious and Inflammatory Disease Center, La Jolla, California, United States of America
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IRC3 regulates mitochondrial translation in response to metabolic cues in Saccharomyces cerevisiae. Mol Cell Biol 2021; 41:e0023321. [PMID: 34398681 DOI: 10.1128/mcb.00233-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) enzymes are made up of dual genetic origin. Mechanisms regulating the expression of nuclear-encoded OXPHOS subunits in response to metabolic cues (glucose vs. glycerol), is significantly understood while regulation of mitochondrially encoded OXPHOS subunits is poorly defined. Here, we show that IRC3 a DEAD/H box helicase, previously implicated in mitochondrial DNA maintenance, is central to integrating metabolic cues with mitochondrial translation. Irc3 associates with mitochondrial small ribosomal subunit in cells consistent with its role in regulating translation elongation based on Arg8m reporter system. IRC3 deleted cells retained mitochondrial DNA despite growth defect on glycerol plates. Glucose grown Δirc3ρ+ and irc3 temperature-sensitive cells at 370C have reduced translation rates from majority of mRNAs. In contrast, when galactose was the carbon source, reduction in mitochondrial translation was observed predominantly from Cox1 mRNA in Δirc3ρ+ but no defect was observed in irc3 temperature-sensitive cells, at 370C. In support, of a model whereby IRC3 responds to metabolic cues to regulate mitochondrial translation, suppressors of Δirc3 isolated for restoration of growth on glycerol media restore mitochondrial protein synthesis differentially in presence of glucose vs. glycerol.
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Muhammad I, Shalmani A, Ali M, Yang QH, Ahmad H, Li FB. Mechanisms Regulating the Dynamics of Photosynthesis Under Abiotic Stresses. FRONTIERS IN PLANT SCIENCE 2020; 11:615942. [PMID: 33584756 PMCID: PMC7876081 DOI: 10.3389/fpls.2020.615942] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 12/28/2020] [Indexed: 05/02/2023]
Abstract
Photosynthesis sustains plant life on earth and is indispensable for plant growth and development. Factors such as unfavorable environmental conditions, stress regulatory networks, and plant biochemical processes limits the photosynthetic efficiency of plants and thereby threaten food security worldwide. Although numerous physiological approaches have been used to assess the performance of key photosynthetic components and their stress responses, though, these approaches are not extensive enough and do not favor strategic improvement of photosynthesis under abiotic stresses. The decline in photosynthetic capacity of plants due to these stresses is directly associated with reduction in yield. Therefore, a detailed information of the plant responses and better understanding of the photosynthetic machinery could help in developing new crop plants with higher yield even under stressed environments. Interestingly, cracking of signaling and metabolic pathways, identification of some key regulatory elements, characterization of potential genes, and phytohormone responses to abiotic factors have advanced our knowledge related to photosynthesis. However, our understanding of dynamic modulation of photosynthesis under dramatically fluctuating natural environments remains limited. Here, we provide a detailed overview of the research conducted on photosynthesis to date, and highlight the abiotic stress factors (heat, salinity, drought, high light, and heavy metal) that limit the performance of the photosynthetic machinery. Further, we reviewed the role of transcription factor genes and various enzymes involved in the process of photosynthesis under abiotic stresses. Finally, we discussed the recent progress in the field of biodegradable compounds, such as chitosan and humic acid, and the effect of melatonin (bio-stimulant) on photosynthetic activity. Based on our gathered researched data set, the logical concept of photosynthetic regulation under abiotic stresses along with improvement strategies will expand and surely accelerate the development of stress tolerance mechanisms, wider adaptability, higher survival rate, and yield potential of plant species.
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Affiliation(s)
- Izhar Muhammad
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, China
| | - Abdullah Shalmani
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, China
| | - Muhammad Ali
- Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Qing-Hua Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, China
| | - Husain Ahmad
- College of Horticulture, Northwest A&F University, Yangling, China
| | - Feng Bai Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, China
- *Correspondence: Feng Bai Li
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Identification and Analysis of Micro-Exon Genes in the Rice Genome. Int J Mol Sci 2019; 20:ijms20112685. [PMID: 31159166 PMCID: PMC6600660 DOI: 10.3390/ijms20112685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/25/2019] [Accepted: 05/29/2019] [Indexed: 11/24/2022] Open
Abstract
Micro-exons are a kind of exons with lengths no more than 51 nucleotides. They are generally ignored in genome annotation due to the short length, whereas recent studies indicate that they have special splicing properties and important functions. Considering that there has been no genome-wide study of micro-exons in plants up to now, we screened and analyzed genes containing micro-exons in two indica rice varieties in this study. According to the annotation of Zhenshan 97 (ZS97) and Minghui 63 (MH63), ~23% of genes possess micro-exons. We then identified micro-exons from RNA-seq data and found that >65% micro-exons had been annotated and most of novel micro-exons were located in gene regions. About 60% micro-exons were constitutively spliced, and the others were alternatively spliced in different tissues. Besides, we observed that approximately 54% of genes harboring micro-exons tended to be ancient genes, and 13% were Oryza genus-specific. Micro-exon genes were highly conserved in Oryza genus with consistent domains. In particular, the predicted protein structures showed that alternative splicing of in-frame micro-exons led to a local structural recombination, which might affect some core structure of domains, and alternative splicing of frame-shifting micro-exons usually resulted in premature termination of translation by introducing a stop codon or missing functional domains. Overall, our study provided the genome-wide distribution, evolutionary conservation, and potential functions of micro-exons in rice.
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Su A, Song W, Xing J, Zhao Y, Zhang R, Li C, Duan M, Luo M, Shi Z, Zhao J. Identification of Genes Potentially Associated with the Fertility Instability of S-Type Cytoplasmic Male Sterility in Maize via Bulked Segregant RNA-Seq. PLoS One 2016; 11:e0163489. [PMID: 27669430 PMCID: PMC5036866 DOI: 10.1371/journal.pone.0163489] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 09/09/2016] [Indexed: 12/16/2022] Open
Abstract
S-type cytoplasmic male sterility (CMS-S) is the largest group among the three major types of CMS in maize. CMS-S exhibits fertility instability as a partial fertility restoration in a specific nuclear genetic background, which impedes its commercial application in hybrid breeding programs. The fertility instability phenomenon of CMS-S is controlled by several minor quantitative trait locus (QTLs), but not the major nuclear fertility restorer (Rf3). However, the gene mapping of these minor QTLs and the molecular mechanism of the genetic modifications are still unclear. Using completely sterile and partially rescued plants of fertility instable line (FIL)-B, we performed bulk segregant RNA-Seq and identified six potential associated genes in minor effect QTLs contributing to fertility instability. Analyses demonstrate that these potential associated genes may be involved in biological processes, such as floral organ differentiation and development regulation, energy metabolism and carbohydrates biosynthesis, which results in a partial anther exsertion and pollen fertility restoration in the partially rescued plants. The single nucleotide polymorphisms (SNPs) identified in two potential associated genes were validated to be related to the fertility restoration phenotype by KASP marker assays. This novel knowledge contributes to the understanding of the molecular mechanism of the partial fertility restoration of CMS-S in maize and thus helps to guide the breeding programs.
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Affiliation(s)
- Aiguo Su
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Wei Song
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Jinfeng Xing
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Yanxin Zhao
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Ruyang Zhang
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Chunhui Li
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Minxiao Duan
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Meijie Luo
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
| | - Zi Shi
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
- * E-mail: (ZS); (JZ)
| | - Jiuran Zhao
- Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Beijing, 100097, China
- * E-mail: (ZS); (JZ)
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Bhushan L, Abraham A, Choudhury NR, Rana VS, Mukherjee SK, Savithri HS. Demonstration of helicase activity in the nonstructural protein, NSs, of the negative-sense RNA virus, groundnut bud necrosis virus. Arch Virol 2015; 160:959-67. [PMID: 25643815 DOI: 10.1007/s00705-014-2331-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 11/30/2014] [Indexed: 12/22/2022]
Abstract
The nonstructural protein NSs, encoded by the S RNA of groundnut bud necrosis virus (GBNV) (genus Tospovirus, family Bunyaviridae) has earlier been shown to possess nucleic-acid-stimulated NTPase and 5' α phosphatase activity. ATP hydrolysis is an essential function of a true helicase. Therefore, NSs was tested for DNA helicase activity. The results demonstrated that GBNV NSs possesses bidirectional DNA helicase activity. An alanine mutation in the Walker A motif (K189A rNSs) decreased DNA helicase activity substantially, whereas a mutation in the Walker B motif resulted in a marginal decrease in this activity. The parallel loss of the helicase and ATPase activity in the K189A mutant confirms that NSs acts as a non-canonical DNA helicase. Furthermore, both the wild-type and K189A NSs could function as RNA silencing suppressors, demonstrating that the suppressor activity of NSs is independent of its helicase or ATPase activity. This is the first report of a true helicase from a negative-sense RNA virus.
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Affiliation(s)
- Lokesh Bhushan
- Department of Biochemistry, New Biological Sciences, Indian Institute of Science, Bangalore, 560012, Karnataka, India
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