0
selected
-
1.
Investigating the cell and developmental biology of plant infection by the rice blast fungus Magnaporthe oryzae.
Eseola, AB, Ryder, LS, Osés-Ruiz, M, Findlay, K, Yan, X, Cruz-Mireles, N, Molinari, C, Garduño-Rosales, M, Talbot, NJ
Fungal genetics and biology : FG & B. 2021;:103562
Abstract
Magnaporthe oryzae is the causal agent of rice blast disease, the most widespread and serious disease of cultivated rice. Live cell imaging and quantitative 4D image analysis have provided new insight into the mechanisms by which the fungus infects host cells and spreads rapidly in plant tissue. In this video review article, we apply live cell imaging approaches to understanding the cell and developmental biology of rice blast disease. To gain entry to host plants, M. oryzae develops a specialised infection structure called an appressorium, a unicellular dome-shaped cell which generates enormous turgor, translated into mechanical force to rupture the leaf cuticle. Appressorium development is induced by perception of the hydrophobic leaf surface and nutrient deprivation. Cargo-independent autophagy in the three-celled conidium, controlled by cell cycle regulation, is essential for appressorium morphogenesis. Appressorium maturation involves turgor generation and melanin pigment deposition in the appressorial cell wall. Once a threshold of turgor has been reached, this triggers re-polarisation which requires regulated generation of reactive oxygen species, to facilitate septin GTPase-dependent cytoskeletal re-organisation and re-polarisation of the appressorium to form a narrow, rigid penetration peg. Infection of host tissue requires a further morphogenetic transition to a pseudohyphal-type of growth within colonised rice cells. At the same time the fungus secretes an arsenal of effector proteins to suppress plant immunity. Many effectors are secreted into host cells directly, which involves a specific secretory pathway and a specialised structure called the biotrophic interfacial complex. Cell-to-cell spread of the fungus then requires development of a specialised structure, the transpressorium, that is used to traverse pit field sites, allowing the fungus to maintain host cell membrane integrity as new living plant cells are invaded. Thereafter, the fungus rapidly moves through plant tissue and host cells begin to die, as the fungus switches to necrotrophic growth and disease symptoms develop. These morphogenetic transitions are reviewed in the context of live cell imaging studies.
-
2.
Exploiting Structural Modelling Tools to Explore Host-Translocated Effector Proteins.
Amoozadeh, S, Johnston, J, Meisrimler, CN
International journal of molecular sciences. 2021;(23)
Abstract
Oomycete and fungal interactions with plants can be neutral, symbiotic or pathogenic with different impact on plant health and fitness. Both fungi and oomycetes can generate so-called effector proteins in order to successfully colonize the host plant. These proteins modify stress pathways, developmental processes and the innate immune system to the microbes' benefit, with a very different outcome for the plant. Investigating the biological and functional roles of effectors during plant-microbe interactions are accessible through bioinformatics and experimental approaches. The next generation protein modeling software RoseTTafold and AlphaFold2 have made significant progress in defining the 3D-structure of proteins by utilizing novel machine-learning algorithms using amino acid sequences as their only input. As these two methods rely on super computers, Google Colabfold alternatives have received significant attention, making the approaches more accessible to users. Here, we focus on current structural biology, sequence motif and domain knowledge of effector proteins from filamentous microbes and discuss the broader use of novel modelling strategies, namely AlphaFold2 and RoseTTafold, in the field of effector biology. Finally, we compare the original programs and their Colab versions to assess current strengths, ease of access, limitations and future applications.
-
3.
Coordinated regulation of iron metabolism in Cryptococcus neoformans by GATA and CCAAT transcription factors: connections with virulence.
Jung, WH, Sánchez-León, E, Kronstad, JW
Current genetics. 2021;(4):583-593
-
-
Free full text
-
Abstract
Iron acquisition is critical for pathogenic fungi to adapt to and survive within the host environment. However, to same extent, the fungi must also avoid the detrimental effects caused by excess iron. The importance of iron has been demonstrated for the physiology and virulence of major fungal pathogens of humans including Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans. In particular, numerous studies have revealed that aspects of iron acquisition, metabolism, and homeostasis in the fungal pathogens are tightly controlled by conserved transcriptional regulators including a GATA-type iron transcription factor and the CCAAT-binding complex (CBC)/HapX orthologous protein complex. However, the specific downstream regulatory networks are slightly different in each fungus. In addition, roles have been proposed or demonstrated for other factors including monothiol glutaredoxins, BolA-like proteins, and Fe-S cluster incorporation on the GATA-type iron transcription factor and the CBC/HapX orthologous protein complex, although limited information is available. Here we focus on recent work on C. neoformans in the context of an emerging framework for fungal regulation of iron acquisition, metabolism, and homeostasis. Our specific goal is to summarize recent findings on transcriptional networks governed by the iron regulators Cir1 and HapX in C. neoformans.
-
4.
DyP-Type Peroxidases: Recent Advances and Perspectives.
Sugano, Y, Yoshida, T
International journal of molecular sciences. 2021;(11)
Abstract
In this review, we chart the major milestones in the research progress on the DyP-type peroxidase family over the past decade. Though mainly distributed among bacteria and fungi, this family actually exhibits more widespread diversity. Advanced tertiary structural analyses have revealed common and different features among members of this family. Notably, the catalytic cycle for the peroxidase activity of DyP-type peroxidases appears to be different from that of other ubiquitous heme peroxidases. DyP-type peroxidases have also been reported to possess activities in addition to peroxidase function, including hydrolase or oxidase activity. They also show various cellular distributions, functioning not only inside cells but also outside of cells. Some are also cargo proteins of encapsulin. Unique, noteworthy functions include a key role in life-cycle switching in Streptomyces and the operation of an iron transport system in Staphylococcus aureus, Bacillus subtilis and Escherichia coli. We also present several probable physiological roles of DyP-type peroxidases that reflect the widespread distribution and function of these enzymes. Lignin degradation is the most common function attributed to DyP-type peroxidases, but their activity is not high compared with that of standard lignin-degrading enzymes. From an environmental standpoint, degradation of natural antifungal anthraquinone compounds is a specific focus of DyP-type peroxidase research. Considered in its totality, the DyP-type peroxidase family offers a rich source of diverse and attractive materials for research scientists.
-
5.
Skin Commensal Fungus Malassezia and Its Lipases.
Park, M, Park, S, Jung, WH
Journal of microbiology and biotechnology. 2021;(5):637-644
Abstract
Malassezia is the most abundant genus in the fungal microflora found on human skin, and it is associated with various skin diseases. Among the 18 different species of Malassezia that have been identified to date, M. restricta and M. globosa are the most predominant fungal species found on human skin. Several studies have suggested a possible link between Malassezia and skin disorders. However, our knowledge on the physiology and pathogenesis of Malassezia in human body is still limited. Malassezia is unable to synthesize fatty acids; hence, it uptakes external fatty acids as a nutrient source for survival, a characteristic compensated by the secretion of lipases and degradation of sebum to produce and uptake external fatty acids. Although it has been reported that the activity of secreted lipases may contribute to pathogenesis of Malassezia, majority of the data were indirect evidences; therefore, enzymes' role in the pathogenesis of Malassezia infections is still largely unknown. This review focuses on the recent advances on Malassezia in the context of an emerging interest for lipases and summarizes the existing knowledge on Malassezia, diseases associated with the fungus, and the role of the reported lipases in its physiology and pathogenesis.
-
6.
Zinc Finger Proteins in the Human Fungal Pathogen Cryptococcus neoformans.
Li, YH, Liu, TB
International journal of molecular sciences. 2020;(4)
Abstract
Zinc is one of the essential trace elements in eukaryotes and it is a critical structural component of a large number of proteins. Zinc finger proteins (ZNFs) are zinc-finger domain-containing proteins stabilized by bound zinc ions and they form the most abundant proteins, serving extraordinarily diverse biological functions. In recent years, many ZNFs have been identified and characterized in the human fungal pathogen Cryptococcus neoformans, a fungal pathogen causing fatal meningitis mainly in immunocompromised individuals. It has been shown that ZNFs play important roles in the morphological development, differentiation, and virulence of C. neoformans. In this review, we, first, briefly introduce the ZNFs and their classification. Then, we explain the identification and classification of the ZNFs in C. neoformans. Next, we focus on the biological role of the ZNFs functionally characterized so far in the sexual reproduction, virulence factor production, ion homeostasis, pathogenesis, and stress resistance in C. neoformans. We also discuss the perspectives on future function studies of ZNFs in C. neoformans.
-
7.
Amyloid-Like β-Aggregates as Force-Sensitive Switches in Fungal Biofilms and Infections.
Lipke, PN, Klotz, SA, Dufrene, YF, Jackson, DN, Garcia-Sherman, MC
Microbiology and molecular biology reviews : MMBR. 2018;(1)
-
-
Free full text
-
Abstract
Cellular aggregation is an essential step in the formation of biofilms, which promote fungal survival and persistence in hosts. In many of the known yeast cell adhesion proteins, there are amino acid sequences predicted to form amyloid-like β-aggregates. These sequences mediate amyloid formation in vitro. In vivo, these sequences mediate a phase transition from a disordered state to a partially ordered state to create patches of adhesins on the cell surface. These β-aggregated protein patches are called adhesin nanodomains, and their presence greatly increases and strengthens cell-cell interactions in fungal cell aggregation. Nanodomain formation is slow (with molecular response in minutes and the consequences being evident for hours), and strong interactions lead to enhanced biofilm formation. Unique among functional amyloids, fungal adhesin β-aggregation can be triggered by the application of physical shear force, leading to cellular responses to flow-induced stress and the formation of robust biofilms that persist under flow. Bioinformatics analysis suggests that this phenomenon may be widespread. Analysis of fungal abscesses shows the presence of surface amyloids in situ, a finding which supports the idea that phase changes to an amyloid-like state occur in vivo. The amyloid-coated fungi bind the damage-associated molecular pattern receptor serum amyloid P component, and there may be a consequential modulation of innate immune responses to the fungi. Structural data now suggest mechanisms for the force-mediated induction of the phase change. We summarize and discuss evidence that the sequences function as triggers for protein aggregation and subsequent cellular aggregation, both in vitro and in vivo.
-
8.
Dynamic Fungal Cell Wall Architecture in Stress Adaptation and Immune Evasion.
Hopke, A, Brown, AJP, Hall, RA, Wheeler, RT
Trends in microbiology. 2018;(4):284-295
-
-
Free full text
-
Abstract
Deadly infections from opportunistic fungi have risen in frequency, largely because of the at-risk immunocompromised population created by advances in modern medicine and the HIV/AIDS pandemic. This review focuses on dynamics of the fungal polysaccharide cell wall, which plays an outsized role in fungal pathogenesis and therapy because it acts as both an environmental barrier and as the major interface with the host immune system. Human fungal pathogens use architectural strategies to mask epitopes from the host and prevent immune surveillance, and recent work elucidates how biotic and abiotic stresses present during infection can either block or enhance masking. The signaling components implicated in regulating fungal immune recognition can teach us how cell wall dynamics are controlled, and represent potential targets for interventions designed to boost or dampen immunity.
-
9.
Microbial 2-Cys Peroxiredoxins: Insights into Their Complex Physiological Roles.
Toledano, MB, Huang, B
Molecules and cells. 2016;(1):31-9
Abstract
The peroxiredoxins (Prxs) constitute a very large and highly conserved family of thiol-based peroxidases that has been discovered only very recently. We consider here these enzymes through the angle of their discovery, and of some features of their molecular and physiological functions, focusing on complex phenotypes of the gene mutations of the 2-Cys Prxs subtype in yeast. As scavengers of the low levels of H2O2 and as H2O2 receptors and transducers, 2-Cys Prxs have been highly instrumental to understand the biological impact of H2O2, and in particular its signaling function. 2-Cys Prxs can also become potent chaperone holdases, and unveiling the in vivo relevance of this function, which is still not established, should further increase our knowledge of the biological impact and toxicity of H2O2. The diverse molecular functions of 2-Cys Prx explain the often-hard task of relating them to peroxiredoxin genes phenotypes, which underscores the pleiotropic physiological role of these enzymes and complex biologic impact of H2O2.
-
10.
Septins and Generation of Asymmetries in Fungal Cells.
Khan, A, McQuilken, M, Gladfelter, AS
Annual review of microbiology. 2015;:487-503
-
-
Free full text
-
Abstract
Polarized growth is critical for the development and maintenance of diverse organisms and tissues but particularly so in fungi, where nutrient uptake, communication, and reproduction all rely on cell asymmetries. To achieve polarized growth, fungi spatially organize both their cytosol and cortical membranes. Septins, a family of GTP-binding proteins, are key regulators of spatial compartmentalization in fungi and other eukaryotes. Septins form higher-order structures on fungal plasma membranes and are thought to contribute to the generation of cell asymmetries by acting as molecular scaffolds and forming diffusional barriers. Here we discuss the links between septins and polarized growth and consider molecular models for how septins contribute to cellular asymmetry in fungi.