On the Edge of Dispensability, the Chloroplast ndh Genes

The polypeptides encoded by the chloroplast ndh genes and some nuclear genes form the thylakoid NADH dehydrogenase (Ndh) complex, homologous to the mitochondrial complex I. Except for Charophyceae (algae related to higher plants) and a few Prasinophyceae, all eukaryotic algae lack ndh genes. Among vascular plants, the ndh genes are absent in epiphytic and in some species scattered among different genera, families, and orders. The recent identification of many plants lacking plastid ndh genes allows comparison on phylogenetic trees and functional investigations of the ndh genes. The ndh genes protect Angiosperms under various terrestrial stresses, maintaining efficient photosynthesis. On the edge of dispensability, ndh genes provide a test for the natural selection of photosynthesis-related genes in evolution. Variable evolutionary environments place Angiosperms without ndh genes at risk of extinction and, probably, most extant ones may have lost ndh genes recently. Therefore, they are evolutionary endpoints in phylogenetic trees. The low number of sequenced plastid DNA and the long lifespan of some Gymnosperms lacking ndh genes challenge models about the role of ndh genes protecting against stress and promoting leaf senescence. Additional DNA sequencing in Gymnosperms and investigations into the molecular mechanisms of their response to stress will provide a unified model of the evolutionary and functional consequences of the lack of ndh genes.

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Microglia in cerebral ischemia: molecular actions and interactionsThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigator's Forum.

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y05-143 ◽

2006 ◽

Vol 84 (1) ◽

pp. 49-59 ◽

Cited By ~ 121

Author(s):

Aaron Y. Lai ◽

Kathryn G. Todd

Keyword(s):

Cerebral Ischemia ◽

Intracellular Signaling ◽

Molecular Mechanisms ◽

Extracellular Signals ◽

Messenger Molecules ◽

Membrane Bound ◽

The Subject ◽

Survey Review ◽

Selection Of

The precise role of microglia in stroke and cerebral ischemia has been the subject of debate for a number of years. Microglia are capable of synthesizing numerous soluble and membrane-bound biomolecules, some known to be neuroprotective, some neurotoxic, whereas others have less definitive bioactivities. The molecular mechanisms through which microglia activate these molecules have thus become an important area of ischemia research. Here we provide a survey review that summarizes the key actions of microglial factors in cerebral ischemia including complement proteins, chemokines, pro-inflammatory cytokines, neurotrophic factors, hormones, and proteinases, as well several important messenger molecules that play a part in how these factors respond to extracellular signals during ischemic injuries. We also provide some new perspectives on how microglial intracellular signaling may contribute to the seemingly contradictory roles of several microglial effector molecules.

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Current Evidence for a Role of Neuropeptides in the Regulation of Autophagy

BioMed Research International ◽

10.1155/2017/5856071 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 7

Author(s):

Elisabetta Catalani ◽

Clara De Palma ◽

Cristiana Perrotta ◽

Davide Cervia

Keyword(s):

Molecular Mechanisms ◽

Current Evidence ◽

Pathological Conditions ◽

Organ Systems ◽

Intercellular Signalling ◽

Physiological Homeostasis ◽

Response To Stress ◽

Autophagic Process ◽

Regulatory Functions

Neuropeptides drive a wide diversity of biological actions and mediate multiple regulatory functions involving all organ systems. They modulate intercellular signalling in the central and peripheral nervous systems as well as the cross talk among nervous and endocrine systems. Indeed, neuropeptides can function as peptide hormones regulating physiological homeostasis (e.g., cognition, blood pressure, feeding behaviour, water balance, glucose metabolism, pain, and response to stress), neuroprotection, and immunomodulation. We aim here to describe the recent advances on the role exerted by neuropeptides in the control of autophagy and its molecular mechanisms since increasing evidence indicates that dysregulation of autophagic process is related to different pathological conditions, including neurodegeneration, metabolic disorders, and cancer.

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Molecular Functions and Pathways of Plastidial Starch Phosphorylase (PHO1) in Starch Metabolism: Current and Future Perspectives

International Journal of Molecular Sciences ◽

10.3390/ijms221910450 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10450

Author(s):

Noman Shoaib ◽

Lun Liu ◽

Asif Ali ◽

Nishbah Mughal ◽

Guowu Yu ◽

...

Keyword(s):

Protein Interactions ◽

Molecular Mechanisms ◽

Higher Plants ◽

Crop Improvement ◽

Starch Biosynthesis ◽

Starch Metabolism ◽

Protein Protein Interactions ◽

Starch Phosphorylase ◽

Integral Role

Starch phosphorylase is a member of the GT35-glycogen-phosphorylase superfamily. Glycogen phosphorylases have been researched in animals thoroughly when compared to plants. Genetic evidence signifies the integral role of plastidial starch phosphorylase (PHO1) in starch biosynthesis in model plants. The counterpart of PHO1 is PHO2, which specifically resides in cytosol and is reported to lack L80 peptide in the middle region of proteins as seen in animal and maltodextrin forms of phosphorylases. The function of this extra peptide varies among species and ranges from the substrate of proteasomes to modulate the degradation of PHO1 in Solanum tuberosum to a non-significant effect on biochemical activity in Oryza sativa and Hordeum vulgare. Various regulatory functions, e.g., phosphorylation, protein–protein interactions, and redox modulation, have been reported to affect the starch phosphorylase functions in higher plants. This review outlines the current findings on the regulation of starch phosphorylase genes and proteins with their possible role in the starch biosynthesis pathway. We highlight the gaps in present studies and elaborate on the molecular mechanisms of phosphorylase in starch metabolism. Moreover, we explore the possible role of PHO1 in crop improvement.

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Filamentation in Candida albicans is modulated by adaptive translation of farnesol signalling genes

10.1101/2021.01.20.427544 ◽

2021 ◽

Author(s):

Carla Oliveira ◽

Ana Rita Guimarães ◽

Inês Correia ◽

Inês Sousa ◽

Ana Poim ◽

...

Keyword(s):

Candida Albicans ◽

Molecular Mechanisms ◽

Phenotypic Diversity ◽

Critical Role ◽

Normal Growth ◽

Morphological Diversity ◽

Growth Conditions ◽

Response To Stress ◽

Variable Morphology

AbstractThe complex biology of the human pathogen Candida albicans is reflected in its remarkable ability to proliferate in numerous body sites, adapt to drastic changes in the environment, form various types of colonies and grow in yeast, pseudo-hyphal and hyphal forms. Much has been learnt in recent years about the relevance of this phenotypic plasticity, but the mechanisms that support it are still not fully understood. We have demonstrated that atypical translation of the CUG codon is a source of unexpected morphological diversity. The CUG codon is translated as both leucine (Leu) (~3%) and serine (Ser) (~97%) in normal growth conditions, but Ser/Leu levels change in response to stress. Remarkably, recombinant C. albicans strains incorporating between 20% and 99% of Leu at CUG sites display a diverse array of phenotypes and produce colonies of variable morphology containing a mixture of yeast, pseudohyphal and hyphal cells. In this work we investigate the role of the CUG codon in the yeast-hypha transition. Our data show that increasing incorporation levels of Leu at CUG sites trigger hyphal initiation under non-inducing conditions by reducing farnesol production, and increasing the degradation of the Nrg1 hyphal repressor. We propose that dual CUG Ser/Leu translation triggers filamentation via the Nrg1 pathway.ImportanceThe unique translation of the CUG codon as both Ser (~97%) and Leu (~3%) plays a key role in the production of high genomic and phenotypic diversity in C. albicans. The molecular mechanisms that support such diversity are poorly understood. Here, we show that increased Leu incorporation at CUG sites induce hyphae formation in media where C. albicans normally grows in the yeast form. The data show that increasing Leu at CUG sites triggers the degradation of the hyphal repressor Nrg1, allowing for full expression of hyphal genes. Since filamentation is important for invasion of host tissues, this work shows how the atypical translation of a single codon may play a critical role in the virulence of all fungi of the CTG clade.

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Fidelity of Cotranslational Protein Targeting to the Endoplasmic Reticulum

International Journal of Molecular Sciences ◽

10.3390/ijms23010281 ◽

2021 ◽

Vol 23 (1) ◽

pp. 281

Author(s):

Hao-Hsuan Hsieh ◽

Shu-ou Shan

Keyword(s):

Molecular Mechanisms ◽

Protein Targeting ◽

Protein Localization ◽

Signal Recognition Particle ◽

Cellular Membrane ◽

Secretory Proteins ◽

Signal Recognition ◽

Substrate Selection ◽

Selection Of

Fidelity of protein targeting is essential for the proper biogenesis and functioning of organelles. Unlike replication, transcription and translation processes, in which multiple mechanisms to recognize and reject noncognate substrates are established in energetic and molecular detail, the mechanisms by which cells achieve a high fidelity in protein localization remain incompletely understood. Signal recognition particle (SRP), a conserved pathway to mediate the localization of membrane and secretory proteins to the appropriate cellular membrane, provides a paradigm to understand the molecular basis of protein localization in the cell. In this chapter, we review recent progress in deciphering the molecular mechanisms and substrate selection of the mammalian SRP pathway, with an emphasis on the key role of the cotranslational chaperone NAC in preventing protein mistargeting to the ER and in ensuring the organelle specificity of protein localization.

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First person – Alessandra Gallo

Journal of Cell Science ◽

10.1242/jcs.253955 ◽

2020 ◽

Vol 133 (18) ◽

pp. jcs253955

Keyword(s):

Molecular Mechanisms ◽

Neurite Growth ◽

Early Career ◽

First Person ◽

Biotech Company ◽

Early Career Researchers ◽

Selection Of

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Alessandra Gallo is first author on ‘Role of the Sec22b–E-Syt complex in neurite growth and ramification’, published in JCS. Alessandra currently works as a medical affairs manager for the biotech company Alzohis, Paris, France, in the lab of Romain Verpillot, investigating the molecular mechanisms of neurodevelopment and neurodegeneration.

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The Role of Alternative Polyadenylation in the Regulation of Subcellular RNA Localization

Frontiers in Genetics ◽

10.3389/fgene.2021.818668 ◽

2022 ◽

Vol 12 ◽

Author(s):

Ankita Arora ◽

Raeann Goering ◽

Hei Yong G. Lo ◽

Joelle Lo ◽

Charlie Moffatt ◽

...

Keyword(s):

Cell Proliferation ◽

Molecular Mechanisms ◽

Regulatory Mechanism ◽

Alternative Polyadenylation ◽

Mrna Localization ◽

Rna Localization ◽

Mrna Isoforms ◽

Cellular Processes ◽

Response To Stress

Alternative polyadenylation (APA) is a widespread and conserved regulatory mechanism that generates diverse 3′ ends on mRNA. APA patterns are often tissue specific and play an important role in cellular processes such as cell proliferation, differentiation, and response to stress. Many APA sites are found in 3′ UTRs, generating mRNA isoforms with different 3′ UTR contents. These alternate 3′ UTR isoforms can change how the transcript is regulated, affecting its stability and translation. Since the subcellular localization of a transcript is often regulated by 3′ UTR sequences, this implies that APA can also change transcript location. However, this connection between APA and RNA localization has only recently been explored. In this review, we discuss the role of APA in mRNA localization across distinct subcellular compartments. We also discuss current challenges and future advancements that will aid our understanding of how APA affects RNA localization and molecular mechanisms that drive these processes.

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Role of Sirtuins in Modulating Neurodegeneration of the Enteric Nervous System and Central Nervous System

Frontiers in Neuroscience ◽

10.3389/fnins.2020.614331 ◽

2020 ◽

Vol 14 ◽

Author(s):

Pavithra Chandramowlishwaran ◽

Anitha Vijay ◽

Daniel Abraham ◽

Ge Li ◽

Simon Musyoka Mwangi ◽

...

Keyword(s):

Nervous System ◽

Histone Deacetylases ◽

Cellular Response ◽

Genome Stability ◽

Molecular Mechanisms ◽

Metabolic Dysfunction ◽

Growth And Survival ◽

Obesity And Diabetes ◽

Response To Stress

Neurodegeneration of the central and enteric nervous systems is a common feature of aging and aging-related diseases, and is accelerated in individuals with metabolic dysfunction including obesity and diabetes. The molecular mechanisms of neurodegeneration in both the CNS and ENS are overlapping. Sirtuins are an important family of histone deacetylases that are important for genome stability, cellular response to stress, and nutrient and hormone sensing. They are activated by calorie restriction (CR) and by the coenzyme, nicotinamide adenine dinucleotide (NAD+). Sirtuins, specifically the nuclear SIRT1 and mitochondrial SIRT3, have been shown to have predominantly neuroprotective roles in the CNS while the cytoplasmic sirtuin, SIRT2 is largely associated with neurodegeneration. A systematic study of sirtuins in the ENS and their effect on enteric neuronal growth and survival has not been conducted. Recent studies, however, also link sirtuins with important hormones such as leptin, ghrelin, melatonin, and serotonin which influence many important processes including satiety, mood, circadian rhythm, and gut homeostasis. In this review, we address emerging roles of sirtuins in modulating the metabolic challenges from aging, obesity, and diabetes that lead to neurodegeneration in the ENS and CNS. We also highlight a novel role for sirtuins along the microbiota-gut-brain axis in modulating neurodegeneration.

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Critical Role of NdhA in the Incorporation of the Peripheral Arm into the Membrane-embedded Part of the Chloroplast NADH Dehydrogenase-like Complex

Plant and Cell Physiology ◽

10.1093/pcp/pcaa143 ◽

2020 ◽

Author(s):

Hiroshi Yamamoto ◽

Nozomi Sato ◽

Toshiharu Shikanai

Keyword(s):

Nadh Dehydrogenase ◽

Critical Role ◽

Pentatricopeptide Repeat ◽

Ppr Protein ◽

Final Assembly ◽

In The Wild ◽

Ndh Genes ◽

Arabidopsis Mutant ◽

Biochemical Analyses

Abstract The chloroplast NADH dehydrogenase-like (NDH) complex mediates ferredoxin-dependent plastoquinone reduction in the thylakoid membrane. In angiosperms, chloroplast NDH is composed of five subcomplexes and further forms a supercomplex with PSI. Subcomplex A (SubA) mediates the electron transport and consists of eight subunits encoded by both plastid and nuclear genomes. The assembly of SubA in the stroma has been extensively studied but it is unclear how SubA is incorporated into the membrane embedded part of the NDH complex. Here, we isolated a novel Arabidopsis mutant chlororespiratory reduction 16 (crr16) defective in NDH activity. CRR16 encodes a chloroplast-localized P-class pentatricopeptide repeat (PPR) protein conserved in angiosperms. Transcript analysis of plastid-encoded ndh genes indicated that CRR16 was responsible for the efficient splicing of the group II intron in the ndhA transcript, which encodes a membrane-embedded subunit localized to the connecting site between SubA and membrane subcomplex (SubM). To analyze the roles of NdhA in the assembly and stability of the NDH complex, the homoplastomic knockout plant of ndhA (ΔndhA) was generated in tobacco (Nicotiana tabacum). Biochemical analyses of crr16 and ΔndhA plants indicated that NdhA was essential for stabilizing SubA and SubE but not for the accumulation of the other three subcomplexes. Furthermore, the crr16 mutant accumulated the SubA assembly intermediates in the stroma more than that in the wild type. These results suggest that NdhA biosynthesis is essential for the incorporation of SubA into the membrane-embedded part of the NDH complex at the final assembly step of the NDH-PSI supercomplex.

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A phospho-regulated ensemble signal motif of α-TAT1 drives dynamic microtubule acetylation

10.1101/2020.09.23.310235 ◽

2020 ◽

Author(s):

Abhijit Deb Roy ◽

Evan G. Gross ◽

Gayatri S. Pillai ◽

Shailaja Seetharaman ◽

Sandrine Etienne-Manneville ◽

...

Keyword(s):

Nuclear Export ◽

Molecular Mechanisms ◽

Cellular Functions ◽

Intrinsically Disordered ◽

Phosphorylated Form ◽

C Terminus ◽

Cancer Mutations ◽

Functional Consequences ◽

Dynamic Microtubule

AbstractSpatiotemporal patterns of microtubule modifications such as acetylation underlie diverse cellular functions. While the molecular identity of the acetylating agent, α-tubulin N-acetyltransferase 1 (α-TAT1), as well as the functional consequences of microtubule acetylation have been revealed, the molecular mechanisms that regulate multi-tasking α-TAT1 action for dynamic acetylation remain obscure. Here we identified a signal motif in the intrinsically disordered C-terminus of α-TAT1, which comprises three functional elements - nuclear export, nuclear import and cytosolic retention. Their balance is tuned via phosphorylation by serine-threonine kinases to determine subcellular localization of α-TAT1. While the phosphorylated form binds to 14-3-3 adapters and accumulates in the cytosol for maximal substrate access, the non-phosphorylated form is sequestered inside the nucleus, thus keeping microtubule acetylation minimal. As cancer mutations have been reported to this motif, the unique ensemble regulation of α-TAT1 localization may hint at a role of microtubule acetylation in aberrant physiological conditions.

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