scholarly journals The C-terminal dimerization motif of cyclase-associated protein is essential for actin monomer regulation

2016 ◽  
Vol 473 (23) ◽  
pp. 4427-4441 ◽  
Author(s):  
Shohei Iwase ◽  
Shoichiro Ono
Keyword(s):  
Regulatory Protein ◽  
Full Length ◽  
Regulatory Function ◽  
Actin Monomer ◽  
Nucleotide Exchange ◽  
Strong Activity ◽  
Filament Dynamics ◽  
Evolutionarily Conserved ◽  
Syndrome Protein

Cyclase-associated protein (CAP) is a conserved actin-regulatory protein that functions together with actin depolymerizing factor (ADF)/cofilin to enhance actin filament dynamics. CAP has multiple functional domains, and the function to regulate actin monomers is carried out by its C-terminal half containing a Wiskott–Aldrich Syndrome protein homology 2 (WH2) domain, a CAP and X-linked retinitis pigmentosa 2 (CARP) domain, and a dimerization motif. WH2 and CARP are implicated in binding to actin monomers and important for enhancing filament turnover. However, the role of the dimerization motif is unknown. Here, we investigated the function of the dimerization motif of CAS-2, a CAP isoform in the nematode Caenorhabditis elegans, in actin monomer regulation. CAS-2 promotes ATP-dependent recycling of ADF/cofilin-bound actin monomers for polymerization by enhancing exchange of actin-bound nucleotides. The C-terminal half of CAS-2 (CAS-2C) has nearly as strong activity as full-length CAS-2. Maltose-binding protein (MBP)-tagged CAS-2C is a dimer. However, MBP-CAS-2C with a truncation of either one or two C-terminal β-strands is monomeric. Truncations of the dimerization motif in MBP-CAS-2C nearly completely abolish its activity to sequester actin monomers from polymerization and enhance nucleotide exchange on actin monomers. As a result, these CAS-2C variants, also in the context of full-length CAS-2, fail to compete with ADF/cofilin to release actin monomers for polymerization. CAS-2C variants lacking the dimerization motif exhibit enhanced binding to actin filaments, which is mediated by WH2. Taken together, these results suggest that the evolutionarily conserved dimerization motif of CAP is essential for its C-terminal region to exert the actin monomer-specific regulatory function.

scholarly journals ThechbGGene of the Chitobiose (chb) Operon of Escherichia coli Encodes a Chitooligosaccharide Deacetylase

2012 ◽  
Vol 194 (18) ◽  
pp. 4959-4971 ◽  
Author(s):  
Subhash Chandra Verma ◽  
Subramony Mahadevan
Keyword(s):  
Escherichia Coli ◽  
Metal Binding ◽  
Inflammatory Diseases ◽  
Regulatory Protein ◽  
Loss Of Function ◽  
Content Type ◽  
Reading Frame ◽  
E Coli ◽  
Evolutionarily Conserved

ABSTRACTThechboperon ofEscherichia coliis involved in the utilization of the β-glucosides chitobiose and cellobiose. The function ofchbG(ydjC), the sixth open reading frame of the operon that codes for an evolutionarily conserved protein is unknown. We show thatchbGencodes a monodeacetylase that is essential for growth on the acetylated chitooligosaccharides chitobiose and chitotriose but is dispensable for growth on cellobiose and chitosan dimer, the deacetylated form of chitobiose. The predicted active site of the enzyme was validated by demonstrating loss of function upon substitution of its putative metal-binding residues that are conserved across the YdjC family of proteins. We show that activation of thechbpromoter by the regulatory protein ChbR is dependent on ChbG, suggesting that deacetylation of chitobiose-6-P and chitotriose-6-P is necessary for their recognition by ChbR as inducers. Strains carrying mutations inchbRconferring the ability to grow on both cellobiose and chitobiose are independent ofchbGfunction for induction, suggesting that gain of function mutations in ChbR allow it to recognize the acetylated form of the oligosaccharides. ChbR-independent expression of the permease and phospho-β-glucosidase from a heterologous promoter did not support growth on both chitobiose and chitotriose in the absence ofchbG, suggesting an additional role ofchbGin the hydrolysis of chitooligosaccharides. The homologs ofchbGin metazoans have been implicated in development and inflammatory diseases of the intestine, indicating that understanding the function ofE. colichbGhas a broader significance.

scholarly journals Novel data about association of the functionally significant polymorphisms of the MMP-9 gene with exfoliation glaucoma in the Caucasian population of Central Russia

2020 ◽  
Author(s):  
Dina Starikova ◽  
Irina Ponomarenko ◽  
Evgeny Reshetnikov ◽  
Volodymyr Dvornyk ◽  
Mikhail Churnosov
Keyword(s):  
Regulatory Protein ◽  
Additive Model ◽  
Caucasian Population ◽  
Control Group ◽  
Regulatory Motifs ◽  
Exfoliation Glaucoma ◽  
Central Russia ◽  
Increased Risk ◽  
Evolutionarily Conserved

Aim: This study aimed to investigate the role of functionally significant polymorphisms of the MMP-1, MMP-3, and MMP-9 genes in the development of exfoliation glaucoma (XFG) in the Caucasian population of Central Russia. Methods: The study sample consisted of 724 participants, including 328 patients with XFG and 396 individuals in the control group. The participants were of Russian ethnicity (self-reported) born in Central Russia. The participants were genotyped at eight functionally significant polymorphisms of the MMP genes (rs3918242, rs3918249, rs17576, rs3787268, rs2250889, rs17577 MMP9, rs679620 MMP3, and rs1799750 MMP1). The association analysis was performed using logistic regression. Two polymorphisms, which were associated with XFG, and 12 polymorphisms linked to them (r2≥0.8) were analyzed for their functional significance in silico. Results: Allele C of rs3918249 MMP9 was associated with XFG according to the additive model (OR = 0.75, 95% CI 0.56-0.93, pperm = 0.015), and allele G of the rs2250889 MMP9 locus was associated with XFG according to the additive (OR = 1.59, 95% CI 1.10-2.29, pperm = 0.013) and dominant (OR = 1.68, 95% CI 1.11- 2.56, рperm = 0.016) models. Two XFG-associated loci of the MMP9 gene и 12 SNPs linked to them had a significant regulatory potential (they are located in the evolutionarily conserved regions, promoter and enhancer histone marks, the DNAase- hypersensitivity regions, a region binding to regulatory protein and a region of regulatory motifs) and may influence the expression of 13 genes and alternative splicing of four genes in various tissues and organs related to the pathogenesis of XFG. Conclusion: Allele C rs3918249 MMP9 decreased risk for XFG (OR = 0.75) and allele G of the rs2250889 MMP9 locus increased risk for XFG (OR = 1.59-1.68) in the Caucasian population of Central Russia.

scholarly journals The H2 Sensor of Ralstonia eutropha Is a Member of the Subclass of Regulatory [NiFe] Hydrogenases

2000 ◽  
Vol 182 (10) ◽  
pp. 2716-2724 ◽  
Author(s):  
Laura Kleihues ◽  
Oliver Lenz ◽  
Michael Bernhard ◽  
Thorsten Buhrke ◽  
Bärbel Friedrich
Keyword(s):  
Ralstonia Eutropha ◽  
Regulatory Protein ◽  
Regulatory System ◽  
Structural Features ◽  
Regulatory Function ◽  
Nickel Iron ◽  
H2 Sensor ◽  
Overexpression System ◽  
Electron Transfer Processes

ABSTRACT Two energy-generating hydrogenases enable the aerobic hydrogen bacterium Ralstonia eutropha (formerly Alcaligenes eutrophus) to use molecular hydrogen as the sole energy source. The complex synthesis of the nickel-iron-containing enzymes has to be efficiently regulated in response to H2, which is available in low amounts in aerobic environments. H2 sensing inR. eutropha is achieved by a hydrogenase-like protein which controls the hydrogenase gene expression in concert with a two-component regulatory system. In this study we show that the H2 sensor of R. eutropha is a cytoplasmic protein. Although capable of H2 oxidation with redox dyes as electron acceptors, the protein did not support lithoautotrophic growth in the absence of the energy-generating hydrogenases. A specifically designed overexpression system for R. eutrophaprovided the basis for identifying the H2 sensor as a nickel-containing regulatory protein. The data support previous results which showed that the sensor has an active site similar to that of prototypic [NiFe] hydrogenases (A. J. Pierik, M. Schmelz, O. Lenz, B. Friedrich, and S. P. J. Albracht, FEBS Lett. 438:231–235, 1998). It is demonstrated that in addition to the enzymatic activity the regulatory function of the H2 sensor is nickel dependent. The results suggest that H2 sensing requires an active [NiFe] hydrogenase, leaving the question open whether only H2 binding or subsequent H2oxidation and electron transfer processes are necessary for signaling. The regulatory role of the H2-sensing hydrogenase ofR. eutropha, which has also been investigated in other hydrogen-oxidizing bacteria, is intimately correlated with a set of typical structural features. Thus, the family of H2 sensors represents a novel subclass of [NiFe] hydrogenases denoted as the “regulatory hydrogenases.”

scholarly journals ATP-dependent regulation of actin monomer–filament equilibrium by cyclase-associated protein and ADF/cofilin

2013 ◽  
Vol 453 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Kazumi Nomura ◽  
Shoichiro Ono
Keyword(s):  
Actin Filaments ◽  
Striated Muscle ◽  
Actin Binding ◽  
Molar Ratio ◽  
Dependent Manner ◽  
Actin Monomer ◽  
Nucleotide Exchange ◽  
C Elegans ◽  
Filament Dynamics ◽  
Steady State Levels

CAP (cyclase-associated protein) is a conserved regulator of actin filament dynamics. In the nematode Caenorhabditis elegans, CAS-1 is an isoform of CAP that is expressed in striated muscle and regulates sarcomeric actin assembly. In the present study, we report that CAS-2, a second CAP isoform in C. elegans, attenuates the actin-monomer-sequestering effect of ADF (actin depolymerizing factor)/cofilin to increase the steady-state levels of actin filaments in an ATP-dependent manner. CAS-2 binds to actin monomers without a strong preference for either ATP– or ADP–actin. CAS-2 strongly enhances the exchange of actin-bound nucleotides even in the presence of UNC-60A, a C. elegans ADF/cofilin that inhibits nucleotide exchange. UNC-60A induces the depolymerization of actin filaments and sequesters actin monomers, whereas CAS-2 reverses the monomer-sequestering effect of UNC-60A in the presence of ATP, but not in the presence of only ADP or the absence of ATP or ADP. A 1:100 molar ratio of CAS-2 to UNC-60A is sufficient to increase actin filaments. CAS-2 has two independent actin-binding sites in its N- and C-terminal halves, and the C-terminal half is necessary and sufficient for the observed activities of the full-length CAS-2. These results suggest that CAS-2 (CAP) and UNC-60A (ADF/cofilin) are important in the ATP-dependent regulation of the actin monomer–filament equilibrium.

The Regulatory Function of the Molecular Chaperone Hsp90 in the Cell Wall Integrity of Pathogenic Fungi

2018 ◽  
Vol 16 (1) ◽  
pp. 44-53
Author(s):  
Marina Campos Rocha ◽  
Camilla Alves Santos ◽  
Iran Malavazi
Keyword(s):  
Cell Wall ◽  
Antifungal Therapy ◽  
Molecular Chaperone ◽  
Regulatory Protein ◽  
Pathogenic Fungi ◽  
Antifungal Drugs ◽  
Cell Wall Integrity ◽  
Regulatory Function ◽  
Loss Of Function ◽  
Hsp90 Inhibition

Different signaling cascades including the Cell Wall Integrity (CWI), the High Osmolarity Glycerol (HOG) and the Ca2+/calcineurin pathways control the cell wall biosynthesis and remodeling in fungi. Pathogenic fungi, such as Aspergillus fumigatus and Candida albicans, greatly rely on these signaling circuits to cope with different sources of stress, including the cell wall stress evoked by antifungal drugs and the host’s response during infection. Hsp90 has been proposed as an important regulatory protein and an attractive target for antifungal therapy since it stabilizes major effector proteins that act in the CWI, HOG and Ca2+/calcineurin pathways. Data from the human pathogen C. albicans have provided solid evidence that loss-of-function of Hsp90 impairs the evolution of resistance to azoles and echinocandin drugs. In A. fumigatus, Hsp90 is also required for cell wall integrity maintenance, reinforcing a coordinated function of the CWI pathway and this essential molecular chaperone. In this review, we focus on the current information about how Hsp90 impacts the aforementioned signaling pathways and consequently the homeostasis and maintenance of the cell wall, highlighting this cellular event as a key mechanism underlying antifungal therapy based on Hsp90 inhibition.

scholarly journals Structure of the full-length human Pannexin1 channel and insights into its role in pyroptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sensen Zhang ◽  
Baolei Yuan ◽  
Jordy Homing Lam ◽  
Jun Zhou ◽  
Xuan Zhou ◽  
...  
Keyword(s):  
Md Simulation ◽  
Potential Role ◽  
Md Simulations ◽  
Full Length ◽  
Inflammasome Activation ◽  
Simulation Studies ◽  
Cryo Electron Microscopy ◽  
Gating Mechanism ◽  
Atp Efflux

AbstractPannexin1 (PANX1) is a large-pore ATP efflux channel with a broad distribution, which allows the exchange of molecules and ions smaller than 1 kDa between the cytoplasm and extracellular space. In this study, we show that in human macrophages PANX1 expression is upregulated by diverse stimuli that promote pyroptosis, which is reminiscent of the previously reported lipopolysaccharide-induced upregulation of PANX1 during inflammasome activation. To further elucidate the function of PANX1, we propose the full-length human Pannexin1 (hPANX1) model through cryo-electron microscopy (cryo-EM) and molecular dynamics (MD) simulation studies, establishing hPANX1 as a homo-heptamer and revealing that both the N-termini and C-termini protrude deeply into the channel pore funnel. MD simulations also elucidate key energetic features governing the channel that lay a foundation to understand the channel gating mechanism. Structural analyses, functional characterizations, and computational studies support the current hPANX1-MD model, suggesting the potential role of hPANX1 in pyroptosis during immune responses.

scholarly journals A novel putative microtubule-associated protein is involved in arbuscule development during arbuscular mycorrhiza formation

2021 ◽  
Author(s):  
Tania Ho-Plágaro ◽  
Raúl Huertas ◽  
María I Tamayo-Navarrete ◽  
Elison Blancaflor ◽  
Nuria Gavara ◽  
...  
Keyword(s):  
Plant Root ◽  
Arbuscular Mycorrhizal ◽  
Host Cells ◽  
Root Cells ◽  
Filament Dynamics ◽  
Fungal Structure ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Mycorrhizal Development

Abstract The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming in order to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb gene, belonging to a Solanaceae group of genes encoding MT-associated proteins for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb OE roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells overexpressing tsb revealed that TSB is involved in MT-bundling. Taken together, our results provide unprecedented insights into the role of novel MT-associated protein in MT rearrangements throughout the different stages of the arbuscule life cycle.

scholarly journals Emerging multifaceted roles of BAP1 complexes in biological processes

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Aileen Patricia Szczepanski ◽  
Lu Wang
Keyword(s):  
Transcriptional Repression ◽  
Target Genes ◽  
Regulatory Mechanisms ◽  
Biological Processes ◽  
Multiprotein Complex ◽  
Downstream Target ◽  
Evolutionarily Conserved ◽  
Complex Forms ◽  
Polycomb Repressive Complex 1

AbstractHistone H2AK119 mono-ubiquitination (H2AK119Ub) is a relatively abundant histone modification, mainly catalyzed by the Polycomb Repressive Complex 1 (PRC1) to regulate Polycomb-mediated transcriptional repression of downstream target genes. Consequently, H2AK119Ub can also be dynamically reversed by the BAP1 complex, an evolutionarily conserved multiprotein complex that functions as a general transcriptional activator. In previous studies, it has been reported that the BAP1 complex consists of important biological roles in development, metabolism, and cancer. However, identifying the BAP1 complex’s regulatory mechanisms remains to be elucidated due to its various complex forms and its ability to target non-histone substrates. In this review, we will summarize recent findings that have contributed to the diverse functional role of the BAP1 complex and further discuss the potential in targeting BAP1 for therapeutic use.

Sign in / Sign up

Export Citation Format

Share Document