scholarly journals Mycosins Are Required for the Stabilization of the ESX-1 and ESX-5 Type VII Secretion Membrane Complexes

mBio ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
Vincent J. C. van Winden ◽  
Roy Ummels ◽  
Sander R. Piersma ◽  
Connie R. Jiménez ◽  
Konstantin V. Korotkov ◽  
...  
Keyword(s):  
Essential Role ◽  
Intervention Strategies ◽  
Independent Function ◽  
Secretion Systems ◽  
The Core ◽  
Proper Functioning ◽  
Type Vii Secretion ◽  
Membrane Complex ◽  
The Stability

ABSTRACT Pathogenic mycobacteria contain up to five type VII secretion (T7S) systems, ESX-1 to ESX-5. One of the conserved T7S components is the serine protease mycosin (MycP). Strikingly, whereas MycP is essential for secretion, the protease activity of MycP 1 in Mycobacterium tuberculosis has been shown to be dispensable for secretion. The essential role of MycP therefore remains unclear. Here we show that MycP 1 and MycP 5 of M. marinum have similar phenotypes, confirming that MycP has a second unknown function that is essential for its T7S system. To investigate whether this role is related to proper functioning of the T7S membrane complex, we first analyzed the composition of the ESX-1 membrane complex and showed that this complex consists of EccBCDE 1 , similarly to what was previously shown for ESX-5. Surprisingly, while mycosins are not an integral part of these purified core complexes, we noticed that the stability of both the ESX-1 complex and the ESX-5 complex is compromised in the absence of their MycP subunit. Additional interaction studies showed that, although mycosins are not part of the central ESX membrane complex, they loosely associate with this complex. We hypothesize that this MycP association with the core membrane complex is crucial for the integrity and functioning of the T7S machinery. IMPORTANCE Among the major virulence factors of pathogenic mycobacteria are the type VII secretion (T7S) systems. Three of these systems, ESX-1, ESX-3, and ESX-5, have been shown to be crucial for virulence or viability. Here we describe the function of mycosin proteases, which are conserved components within these systems. We show that MycP 1 and MycP 5 have a second, proteolytic-independent function which is essential for the T7S system. We additionally found that this second essential role is related to the stabilization and proper functioning of their respective ESX membrane core complexes. Finally, we found that this is mediated by a loose association of MycP with the complex. Understanding the essential role of mycosins in type VII secretion systems, which play central roles in the virulence and viability of pathogenic mycobacteria, may provide new intervention strategies to treat tuberculosis.

scholarly journals Mycobacterial Pan-Genome Analysis Suggests Important Role of Plasmids in the Radiation of Type VII Secretion Systems

2016 ◽  
Vol 8 (2) ◽  
pp. 387-402 ◽  
Author(s):  
Emilie Dumas ◽  
Eva Christina Boritsch ◽  
Mathias Vandenbogaert ◽  
Ricardo C. Rodríguez de la Vega ◽  
Jean-Michel Thiberge ◽  
...  
Keyword(s):  
Genome Analysis ◽  
Secretion Systems ◽  
Pan Genome ◽  
Type Vii Secretion

scholarly journals Role of Vif in Stability of the Human Immunodeficiency Virus Type 1 Core

2000 ◽  
Vol 74 (23) ◽  
pp. 11055-11066 ◽  
Author(s):  
Åsa Öhagen ◽  
Dana Gabuzda
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dna Synthesis ◽  
Virus Entry ◽  
Wild Type ◽  
The Core ◽  
Immunodeficiency Virus ◽  
The Stability ◽  
Hiv 1

ABSTRACT The Vif protein of human immunodeficiency virus type 1 (HIV-1) is important for virion infectivity. Previous studies have shown thatvif-defective virions exhibit structural abnormalities in the virus core and are defective in the ability to complete proviral DNA synthesis in acutely infected cells. We developed novel assays to assess the relative stability of the core in HIV-1 virions. Using these assays, we examined the role of Vif in the stability of the HIV-1 core. The integrity of the core was examined following virion permeabilization or removal of the lipid envelope and treatment with various triggers, including S100 cytosol, deoxynucleoside triphosphates, detergents, NaCl, and buffers of different pH to mimic aspects of the uncoating and disassembly process which occurs after virus entry but preceding or during reverse transcription.vif mutant cores were more sensitive to disruption by all triggers tested than wild-type cores, as determined by endogenous reverse transcriptase (RT) assays, biochemical analyses, and electron microscopy. RT and the p7 nucleocapsid protein were released more readily from vif mutant virions than from wild-type virions, suggesting that the internal nucleocapsid is less stably packaged in the absence of Vif. Purified cores could be isolated from wild-type but not vif mutant virions by sedimentation through detergent-treated gradients. These results demonstrate that Vif increases the stability of virion cores. This may permit efficient viral DNA synthesis by preventing premature degradation or disassembly of viral nucleoprotein complexes during early events after virus entry.

scholarly journals A type VII secretion system in Group B Streptococcus mediates cytotoxicity and virulence

2021 ◽  
Vol 17 (12) ◽  
pp. e1010121
Author(s):  
Brady L. Spencer ◽  
Uday Tak ◽  
Jéssica C. Mendonça ◽  
Prescilla E. Nagao ◽  
Michael Niederweis ◽  
...  
Keyword(s):  
Group B Streptococcus ◽  
Bioinformatic Analysis ◽  
Effector Proteins ◽  
Dependent Manner ◽  
Secretion Systems ◽  
Gram Positive Bacteria ◽  
Type Vii Secretion ◽  
Type Vii Secretion System ◽  
Group B

Type VII secretion systems (T7SS) have been identified in Actinobacteria and Firmicutes and have been shown to secrete effector proteins with functions in virulence, host toxicity, and/or interbacterial killing in a few genera. Bioinformatic analysis indicates that isolates of Group B Streptococcus (GBS) encode at least four distinct subtypes of T7SS machinery, three of which encode adjacent putative T7SS effectors with WXG and LXG motifs. However, the function of T7SS in GBS pathogenesis is unknown. Here we assessed the role of the most abundant GBS T7SS subtype during GBS pathogenesis. In a murine model of hematogenous meningitis, mice infected with GBS lacking a functional T7SS or lacking the secreted WXG100 effector EsxA exhibited less mortality, lower bacterial burdens in tissues, and decreased inflammation in the brain compared to mice infected with the parental GBS strain. We further showed that this T7SS induces cytotoxicity in brain endothelium and that EsxA contributes to these cytotoxicity phenotypes in a WXG motif-dependent manner. Finally, we determined that EsxA is a pore-forming protein, thus demonstrating the first role for a non-mycobacterial EsxA homolog in pore formation. This work reveals the importance of a T7SS in host–GBS interactions and has implications for T7SS effector function in other Gram-positive bacteria.

scholarly journals Structure and dynamics of the ESX-5 type VII secretion system of Mycobacterium tuberculosis

2020 ◽  
Author(s):  
Catalin M. Bunduc ◽  
Dirk Fahrenkamp ◽  
Jiri Wald ◽  
Roy Ummels ◽  
Wilbert Bitter ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Protein Transport ◽  
Cell Envelope ◽  
Transmembrane Helix ◽  
Transport Systems ◽  
Secretion Systems ◽  
Type Vii Secretion ◽  
Membrane Complex ◽  
Type Vii Secretion System ◽  
Inner Membrane Complex

AbstractMycobacterium tuberculosis causes one of the most important infectious diseases in humans, leading to 1.5 million deaths every year. Specialized protein transport systems, called type VII secretion systems (T7SSs), are central for its virulence, but also crucial for nutrient and metabolite transport across the mycobacterial cell envelope. Here we present the first structure of an intact T7SS inner membrane complex of M. tuberculosis. We show how the 2.32 MDa, 165 transmembrane helices-containing ESX-5 assembly is restructured and stabilized as a trimer of dimers by the MycP5 protease. A trimer of MycP5 caps a central periplasmic dome-like chamber formed by three EccB5 dimers, with the proteolytic sites facing towards the cavity. This chamber suggests a central secretion and processing conduit. Complexes without MycP5 show disruption of the EccB5 periplasmic assembly and increased flexibility, highlighting the importance of this component for complex integrity. Beneath the EccB5-MycP5 chamber, dimers of the EccC5 ATPase assemble into three four-transmembrane helix bundles, which together seal the potential central secretion channel. Individual cytoplasmic EccC5 domains adopt two distinctive conformations, likely reflecting different secretion states. Our work suggests a novel mechanism of protein transport and provides a structural scaffold to aid drug development against the major human pathogen.

Proteasome activator Blm10 regulates transcription especially during aging

2021 ◽  
Vol 22 ◽  
Author(s):  
Yu-Shan Chen ◽  
Xia Han ◽  
Kui Lin ◽  
Tian-Xia Jiang ◽  
Xiao-Bo Qiu
Keyword(s):  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Cellular Aging ◽  
Yeast Cells ◽  
Histone Marks ◽  
Proteasome Activator ◽  
The Core ◽  
Core Histones ◽  
The Stability

Background: Histones are basic elements of the chromatin, and are critical to controlling chromatin structure and transcription. The proteasome activator PA200 promotes the acetylation-dependent proteasomal degradation of the core histones during spermatogenesis, DNA repair, transcription and cellular aging, and maintains the stability of histone marks. Objective: The study aimed to explore whether the yeast ortholog of PA200, Blm10, promotes degradation of the core histones during transcription and regulates transcription especially during aging. Method: Protein degradation assays were performed to detect the role of Blm10 in histone degradation during transcription. mRNA profiles were compared in WT and mutant BY4741 or MDY510 yeast cells by RNA-sequencing. Results: The core histones can be degraded by the Blm10-proteasome in the non-replicating yeast, suggesting that Blm10 promotes the transcription-coupled degradation of the core histones. Blm10 preferentially regulates transcription in aged yeast, especially transcription of genes related to translation, amino acid metabolism and carbohydrate metabolism. Mutations of Blm10 at F2125/N2126 in its putative acetyl-lysine binding region abolished the Blm10-mediated regulation of gene expression. Conclusion: Blm10 promotes degradation of the core histones during transcription and regulates transcription especially during cellular aging, further supporting the critical role of PA200 in maintaining the stability of histone marks from the evolutionary view. These results should provide meaningful insights into the mechanisms underlying aging and the related diseases.

scholarly journals WhiB5, a Transcriptional Regulator That Contributes to Mycobacterium tuberculosis Virulence and Reactivation

2012 ◽  
Vol 80 (9) ◽  
pp. 3132-3144 ◽  
Author(s):  
Stefano Casonato ◽  
Axel Cervantes Sánchez ◽  
Hirohito Haruki ◽  
Monica Rengifo González ◽  
Roberta Provvedi ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Chronic Infection ◽  
Null Mutant ◽  
Wild Type ◽  
Secretion Systems ◽  
Content Type ◽  
Type Vii Secretion ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACTThe proteins belonging to the WhiB superfamily are small global transcriptional regulators typical of actinomycetes. In this paper, we characterize the role of WhiB5, aMycobacterium tuberculosisprotein belonging to this superfamily. A null mutant was constructed inM. tuberculosisH37Rv and was shown to be attenuated during both progressive and chronic mouse infections. Mice infected with the mutant had smaller bacillary burdens in the lungs but a larger inflammatory response, suggesting a role of WhiB5 in immunomodulation. Most interestingly, thewhiB5mutant was not able to resume growth after reactivation from chronic infection, suggesting that WhiB5 controls the expression of genes involved in this process. The mutant was also more sensitive than the wild-type parental strain toS-nitrosoglutathione (GSNO) and was less metabolically active following prolonged starvation, underscoring the importance of GSNO and starvation in development and maintenance of chronic infection. DNA microarray analysis identified 58 genes whose expression is influenced by WhiB5, includingsigM, encoding an alternative sigma factor, and genes encoding the constituents of two type VII secretion systems, namely, ESX-2 and ESX-4.

scholarly journals Role of Metal-Dependent Regulation of ESX-3 Secretion in Intracellular Survival of Mycobacterium tuberculosis

2016 ◽  
Vol 84 (8) ◽  
pp. 2255-2263 ◽  
Author(s):  
Emir Tinaztepe ◽  
Jun-Rong Wei ◽  
Jenelle Raynowska ◽  
Cynthia Portal-Celhay ◽  
Victor Thompson ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Envelope ◽  
Bacterial Pathogen ◽  
Transcriptional Response ◽  
Secretion Systems ◽  
Content Type ◽  
Type Vii Secretion ◽  
Significant Difference ◽  
Iron And Zinc

More people die every year fromMycobacterium tuberculosisinfection than from infection by any other bacterial pathogen. Type VII secretion systems (T7SS) are used by both environmental and pathogenic mycobacteria to secrete proteins across their complex cell envelope. In the nonpathogenMycobacterium smegmatis, the ESX-1 T7SS plays a role in conjugation, and the ESX-3 T7SS is involved in metal homeostasis. InM. tuberculosis, these secretion systems have taken on roles in virulence, and they also are targets of the host immune response. ESX-3 secretes a heterodimer composed of EsxG (TB9.8) and EsxH (TB10.4), which impairs phagosome maturation in macrophages and is essential for virulence in mice. Given the importance of EsxG and EsxH during infection, we examined their regulation. WithM. tuberculosis, the secretion of EsxG and EsxH was regulated in response to iron and zinc, in accordance with the previously described transcriptional response of theesx-3locus to these metals. While iron regulated theesx-3expression in bothM. tuberculosisandM. smegmatis, there is a significant difference in the dynamics of this regulation. InM. smegmatis, theesx-3locus behaved like other iron-regulated genes such asmbtB. InM. tuberculosis, both iron and zinc modestly repressedesx-3expression. Diminished secretion of EsxG and EsxH in response to these metals altered the interaction ofM. tuberculosiswith macrophages, leading to impaired intracellularM. tuberculosissurvival. Our findings detail the regulatory differences ofesx-3inM. tuberculosisandM. smegmatisand demonstrate the importance of metal-dependent regulation of ESX-3 for virulence inM. tuberculosis.

scholarly journals The role of executive bodies as subjects of the economic security system of Ukraine

2021 ◽  
pp. 86-92
Author(s):  
V.I. Melnyk
Keyword(s):  
National Economy ◽  
Legal Status ◽  
Economic Security ◽  
Security System ◽  
Effective Protection ◽  
Proper Functioning ◽  
National Economic ◽  
The Stability ◽  
Definition Of

The article is devoted to the role of executive bodies as subjects of the economic security system of Ukraine. Attention is drawn to the importance of effective administrative activity as one of the basic preconditions for the proper functioning of various branches of the economic sector. It is noted that such activity is of great strategic importance in the issues of ensuring the stability of the national economy and facilitating the necessary development of the latter. An attempt is made to prove that an important role, given their goals, objectives, functions and constitutionally established appointments, is assigned to the executive authorities to facilitate the proper functioning of the national economic system. It has been noted that, among all other bodies of State power, entities have undoubtedly played a significant role in this process and have a special place in the existing State machinery. Attention is drawn to the issues of the concept, as well as to the definition of the structure of the administrative and legal status of the subjects in question. The purpose, tasks and functions of executive bodies as subjects of the system of economic security of Ukraine are defined and characterized. Competence of the said structures in this direction of scientific research is determined, key powers of executive authorities as subjects of the national system of economic security are singled out. It is noted that great importance is given to development of general and coordinated activity of executive authorities, taking into account complexity and multifaceted nature of national economy. It has been noted and an attempt has been made to prove that strengthening external and internal cooperation is a weighty prerequisite for the effective protection of the economic component. It is pointed out that this is especially important in the context of active globalization processes, including those related to the economic sphere. It is noted that such practice also takes place in most EU countries and shows positive statistics from this activity.

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