The axonemal microtubules of the Chlamydomonas flagellum differ in tubulin isoform content

1998 ◽  
Vol 111 (3) ◽  
pp. 313-320 ◽  
Author(s):  
K.A. Johnson
Keyword(s):  
Structure And Function ◽  
Post Translational Modification ◽  
Immunofluorescence Analysis ◽  
Central Pair ◽  
Alpha Tubulin ◽  
Microtubule Polymerization ◽  
Tubulin Isoforms ◽  
Flagellar Assembly ◽  
Tyrosinated Tubulin ◽  
And Function

Little is known of the molecular basis for the diversity of microtubule structure and function found within the eukaryotic flagellum. Antibodies that discriminate between tyrosinated alpha tubulin and post-translationally detyrosinated alpha tubulin were used to localize these complementary tubulin isoforms in flagella of the single-celled green alga Chlamydomonas reinhardtii. Immunofluorescence analysis of intact axonemes detected both isoforms along most of the lengths of flagella; however, each had a short distal zone rich in tyrosinated tubulin. Localizations on splayed axonemes revealed that the microtubules of the central-pair apparatus were rich in tyrosinated tubulin, while outer doublets contained a mixture of both isoforms. Immunoelectron analysis of individual outer doublets revealed that while tyrosinated tubulin was present in both A and B tubules, detyrosinated tubulin was largely confined to the wall of the B hemi-tubules. The absence of detyrosinated tubulin from the A tubules of the outer doublets and the microtubules of the central pair, both of which extend past the B hemi-tubules of the outer doublets in the flagellar tip, explained the appearance of a tyrosinated tubulin-rich distal zone on intact axonemes. Localizations performed on cells regenerating flagella revealed that flagellar assembly used tyrosinated tubulin; detyrosination of the B tubule occurred during later stages of regeneration, well after microtubule polymerization. The developmental timing of detyrosination, which occurs over a period during which the regrowing flagella begin to beat more effectively, suggests that post-translational modification of the B tubule surface may enhance dynein/B tubule interactions that power flagellar beating.

scholarly journals Neddylation regulation of mitochondrial structure and functions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qiyin Zhou ◽  
Yawen Zheng ◽  
Yi Sun
Keyword(s):  
Structure And Function ◽  
Post Translational Modification ◽  
Exciting Field ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Mitochondrial Regulation ◽  
A Cell ◽  
And Function ◽  
Multiple Signaling ◽  
Ring E3 Ligases

AbstractMitochondria are the powerhouse of a cell. The structure and function of mitochondria are precisely regulated by multiple signaling pathways. Neddylation, a post-translational modification, plays a crucial role in various cellular processes including cellular metabolism via modulating the activity, function and subcellular localization of its substrates. Recently, accumulated data demonstrated that neddylation is involved in regulation of morphology, trafficking and function of mitochondria. Mechanistic elucidation of how mitochondria is modulated by neddylation would further our understanding of mitochondrial regulation to a new level. In this review, we first briefly introduce mitochondria, then neddylation cascade, and known protein substrates subjected to neddylation modification. Next, we summarize current available data of how neddylation enzymes, its substrates (including cullins/Cullin-RING E3 ligases and non-cullins) and its inhibitor MLN4924 regulate the structure and function of mitochondria. Finally, we propose the future perspectives on this emerging and exciting field of mitochondrial research.

Monoclonal and polyclonal antibodies detect a new type of post-translational modification of axonemal tubulin

1995 ◽  
Vol 108 (9) ◽  
pp. 3013-3028 ◽  
Author(s):  
N. Levilliers ◽  
A. Fleury ◽  
A.M. Hill
Keyword(s):  
Polyclonal Antibodies ◽  
Microtubule Assembly ◽  
Fusion Peptides ◽  
Post Translational Modification ◽  
Beta Tubulin ◽  
Post Translational Modifications ◽  
Alpha Tubulin ◽  
Tubulin Isoforms ◽  
Molecular Masses ◽  
New Type

Polyclonal (PAT) and monoclonal (AXO 49) antibodies against Paramecium axonemal tubulin were used as probes to reveal tubulin heterogeneity. The location, the nature and the subcellular distribution of the epitopes recognized by these antibodies were, respectively, determined by means of: (i) immunoblotting on peptide maps of Paramecium, sea urchin and quail axonemal tubulins; (ii) immunoblotting on ciliate tubulin fusion peptides generated in E. coli to discriminate antibodies directed against sequential epitopes (reactive) from post-translational ones (non reactive); and (iii) immunofluorescence on Paramecium cells, using throughout an array of antibodies directed against tubulin sequences and post-translational modifications as references. AXO 49 monoclonal antibody and PAT serum were both shown to recognize epitopes located near the carboxyl-terminal end of both subunits of Paramecium axonemal tubulin, whereas the latter recognized additional epitopes in alpha-tubulin; AXO 49 and a fraction of the PAT serum proved to be unreactive over fusion proteins; both PAT and AXO 49 labelled a restricted population of very stable microtubules in Paramecium, consisting of axonemal and cortical ones, and their reactivity was sequentially detected following microtubule assembly; finally, both antibodies stained two upward spread bands in Paramecium axonemal tubulin separated by SDS-PAGE, indicating the recognition of various alpha- and beta-tubulin isoforms displaying different apparent molecular masses. These data, taken as a whole, definitely establish that PAT and AXO 49 recognize a post-translational modification occurring in axonemal microtubules of protozoa as of metazoa. This modification appears to be distinct from the previously known ones, and all the presently available evidence indicates that it corresponds to the very recently discovered polyglycylation of Paramecium axonemal alpha- and beta-tubulin.

Development and maintenance of synaptic structure is mediated by the alpha-tubulin acetyltransferase MEC-17/αTAT1

2019 ◽  
Author(s):  
Jean-Sébastien Teoh ◽  
Wenyue Wang ◽  
Gursimran Chandhok ◽  
Roger Pocock ◽  
Brent Neumann
Keyword(s):  
Leucine Zipper ◽  
Structure And Function ◽  
Loss Of Function ◽  
Neuronal Structure ◽  
Alpha Tubulin ◽  
Synaptic Structure ◽  
Dynamic Structures ◽  
And Function ◽  
Actin Remodelling ◽  
Acetyltransferase Domain

Microtubules are fundamental elements of neuronal structure and function. They are dynamic structures formed from protofilament chains of α- and β-tubulin heterodimers. Acetylation of the lysine 40 (K40) residue of α-tubulin protects microtubules from mechanical stresses by imparting structural elasticity. The enzyme responsible for this acetylation event is MEC-17/αTAT1. However, despite its functional importance, the consequences of MEC-17/αTAT1 misregulation on neuronal structure and function are incompletely defined. Using overexpression and loss of function approaches, we have analysed the effects of MEC-17 misregulation on the development and maintenance of synaptic branches in the mechanosensory neurons of Caenorhabditis elegans. We find that synaptic branch extension is delayed, and that synaptogenesis is defective in these animals. Strikingly, by adulthood the synaptic branches specifically and spontaneously degenerate. This phenotype is dependent on the acetyltransferase domain on MEC-17, revealing that correct levels of K40 acetylation are essential for the maintenance of neuronal structure. Finally, we investigate the genetic pathways in which mec-17 functions, uncovering novel interactions with dual leucine-zipper kinase dlk-1 and the focal adhesion gene zyx-1/Zyxin. These interactions link MEC-17 together with factors involved in neuronal and actin remodelling to protect synaptic branches. Together, our results reveal that appropriate levels of α-tubulin K40 acetylation by MEC-17 are crucial for the development and maintenance of neuronal architecture.

scholarly journals Mitochondrial Kinases and the Role of Mitochondrial Protein Phosphorylation in Health and Disease

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 82
Author(s):  
Veronika Kotrasová ◽  
Barbora Keresztesová ◽  
Gabriela Ondrovičová ◽  
Jacob A. Bauer ◽  
Henrieta Havalová ◽  
...  
Keyword(s):  
Mitochondrial Biogenesis ◽  
Mitochondrial Protein ◽  
Structure And Function ◽  
Stress Factors ◽  
Mitochondrial Proteins ◽  
Post Translational Modification ◽  
Mitochondrial Structure ◽  
Health And Disease ◽  
And Function

The major role of mitochondria is to provide cells with energy, but no less important are their roles in responding to various stress factors and the metabolic changes and pathological processes that might occur inside and outside the cells. The post-translational modification of proteins is a fast and efficient way for cells to adapt to ever changing conditions. Phosphorylation is a post-translational modification that signals these changes and propagates these signals throughout the whole cell, but it also changes the structure, function and interaction of individual proteins. In this review, we summarize the influence of kinases, the proteins responsible for phosphorylation, on mitochondrial biogenesis under various cellular conditions. We focus on their role in keeping mitochondria fully functional in healthy cells and also on the changes in mitochondrial structure and function that occur in pathological processes arising from the phosphorylation of mitochondrial proteins.

scholarly journals 3D Structure and Function of Glycosyltransferases Involved in N-glycan Maturation

2020 ◽  
Vol 21 (2) ◽  
pp. 437 ◽  
Author(s):  
Masamichi Nagae ◽  
Yoshiki Yamaguchi ◽  
Naoyuki Taniguchi ◽  
Yasuhiko Kizuka
Keyword(s):  
Reaction Mechanisms ◽  
Recent Progress ◽  
Protein Transport ◽  
3D Structure ◽  
Biological Significance ◽  
Structure And Function ◽  
Glycan Structure ◽  
Post Translational Modification ◽  
Biochemical Studies ◽  
And Function

Glycosylation is the most ubiquitous post-translational modification in eukaryotes. N-glycan is attached to nascent glycoproteins and is processed and matured by various glycosidases and glycosyltransferases during protein transport. Genetic and biochemical studies have demonstrated that alternations of the N-glycan structure play crucial roles in various physiological and pathological events including progression of cancer, diabetes, and Alzheimer’s disease. In particular, the formation of N-glycan branches regulates the functions of target glycoprotein, which are catalyzed by specific N-acetylglucosaminyltransferases (GnTs) such as GnT-III, GnT-IVs, GnT-V, and GnT-IX, and a fucosyltransferase, FUT8s. Although the 3D structures of all enzymes have not been solved to date, recent progress in structural analysis of these glycosyltransferases has provided insights into substrate recognition and catalytic reaction mechanisms. In this review, we discuss the biological significance and structure-function relationships of these enzymes.

The Apparent Flexural Rigidity of the Flagellar Axoneme Depends on Resistance to Inter-Doublet Sliding

2012 ◽  
Author(s):  
Gang Xu ◽  
Kate S. Wilson ◽  
Ruth J. Okamoto ◽  
Jin-Yu Shao ◽  
Susan K. Dutcher ◽  
...  
Keyword(s):  
Flexural Rigidity ◽  
Motor Protein ◽  
Structure And Function ◽  
Central Pair ◽  
Subcellular Organelles ◽  
And Function ◽  
Flagellar Axoneme ◽  
Mechanical Feedback

Cilia are thin subcellular organelles that bend actively to propel fluid. The ciliary cytoskeleton (the axoneme) consists of nine outer microtubule doublets surrounding a central pair of singlet microtubules. Large bending deformations of the axoneme involve relative sliding of the outer doublets, driven by the motor protein dynein. Ciliary structure and function have been studied extensively, but details of the mechanics and coordination of the axoneme remain unclear. In particular, dynein activity must be switched on and off at specific times and locations to produce an oscillatory, propulsive beat. Leading hypotheses assert that mechanical feedback plays a role in the control of dynein activity, but these ideas remain speculative.

scholarly journals A synopsis of recent developments defining how N-glycosylation impacts immunoglobulin G structure and function

Glycobiology ◽  
2019 ◽  
Vol 30 (4) ◽  
pp. 214-225 ◽  
Author(s):  
Yoshiki Yamaguchi ◽  
Adam W Barb
Keyword(s):  
Immunoglobulin G ◽  
Underlying Mechanism ◽  
Structure And Function ◽  
Post Translational Modification ◽  
Drug Conjugates ◽  
Coated Particle ◽  
Recent Developments ◽  
Dependent Cell ◽  
And Function ◽  
Therapeutic Monoclonal Antibodies

Abstract Therapeutic monoclonal antibodies (mAbs) are the fastest growing group of drugs with 11 new antibodies or antibody-drug conjugates approved by the Food and Drug Administration in 2018. Many mAbs require effector function for efficacy, including antibody-dependent cell-mediated cytotoxicity triggered following contact of an immunoglobulin G (IgG)-coated particle with activating crystallizable fragment (Fc) γ receptors (FcγRs) expressed by leukocytes. Interactions between IgG1 and the FcγRs require post-translational modification of the Fc with an asparagine-linked carbohydrate (N-glycan). Though the structure of IgG1 Fc and the role of Fc N-glycan composition on disease were known for decades, the underlying mechanism of how the N-glycan affected FcγR binding was not defined until recently. This review will describe the current understanding of how N-glycosylation impacts the structure and function of the IgG1 Fc and describe new techniques that are poised to provide the next critical breakthroughs.

The extended tubulin superfamily

2001 ◽  
Vol 114 (15) ◽  
pp. 2723-2733 ◽  
Author(s):  
Paul G. McKean ◽  
Sue Vaughan ◽  
Keith Gull
Keyword(s):  
Cell Biology ◽  
Structure And Function ◽  
Microtubule Assembly ◽  
Eukaryotic Cells ◽  
Current Evidence ◽  
Post Translational Modification ◽  
Tubulin Isotypes ◽  
The Past ◽  
And Function

Although most eukaryotic cells can express multiple isotypes of αβ-tubulin, the significance of this diversity has not always been apparent. Recent data indicate that particular αβ-tubulin isotypes, both genome encoded and those derived by post-translational modification, can directly influence microtubule structure and function — thus validating ideas originally proposed in the multitubulin hypothesis over 25 years ago.It has also become increasingly evident over the past year that some (but intriguingly not all) eukaryotes encode several other tubulin proteins, and to date five further members of the tubulin superfamily, γ, δ, ϵ, 𝛇 and η, have been identified. Although the role of γ-tubulin in the nucleation of microtubule assembly is now well established, far less is known about the functions of δ-, ϵ-, 𝛇- and η-tubulin. Recent work has expanded our knowledge of the functions and localisation of these newer members of the tubulin superfamily, and the emerging data suggesting a restricted evolutionary distribution of these `new' tubulin proteins, conforms to established knowledge of microtubule cell biology. On the basis of current evidence, we predict that δ-, ϵ-, 𝛇- and η-tubulin all have functions associated with the centriole or basal body of eukaryotic cells and organisms.

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