Localization and evolution of septins in algae

Yamazaki, T.; Owari, Satomi; Ota, Shuhei; Sumiya, Nobuko; Yamamoto, Maki; Watanabe, Koichi; Nagumo, Tamotsu; Miyamura, Shinichi; Kawano, Shigeyuki

doi:10.1111/tpj.12147

Cited by 24 publications

(27 citation statements)

References 42 publications

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“…Finally, the role of the aspE septins, the presumed ancestral septins found in filamentous fungi and certain ciliates and algae, but missing from yeasts and animals (Pan et al, 2007; Nishihama et al, 2011; Yamazaki et al, 2013), may offer a clue to how filamentous fungi have maintained a diverse septin repertoire to condition morphogenetic plasticity. Perhaps AspE-type septins facilitate unique hetero-oligomeric associations during different developmental stages.…”

Section: How Do Septins Focus Invasive Growth By Fungi?mentioning

confidence: 99%

Septins Focus Cellular Growth for Host Infection by Pathogenic Fungi

Momany

Talbot

2017

Front. Cell Dev. Biol.

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One of the key challenges faced by microbial pathogens is invasion of host tissue. Fungal pathogens adopt a number of distinct strategies to overcome host cell defenses, including the development of specialized infection structures, the secretion of proteins that manipulate host responses or cellular organization, and the ability to facilitate their own uptake by phagocytic mechanisms. Key to many of these adaptations is the considerable morphogenetic plasticity displayed by pathogenic species. Fungal pathogens can, for example, shift their growth habit between non-polarized spores, or yeast-like cells, and highly polarized hyphal filaments. These polarized filaments can then elaborate differentiated cells, specialized to breach host barriers. Septins play fundamental roles in the ability of diverse fungi to undergo shape changes and organize the F-actin cytoskeleton to facilitate invasive growth. As a consequence, septins are increasingly implicated in fungal pathogenesis, with many septin mutants displaying impairment in their ability to cause diseases of both plants and animals. In this mini-review, we show that a common feature of septin mutants is the emergence of extra polar outgrowths during morphological transitions, such as emergence of germ tubes from conidia or branches from hyphae. We propose that because septins detect and stabilize membrane curvature, they prevent extra polar outgrowths and thereby focus fungal invasive force, allowing substrate invasion.

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Section: How Do Septins Focus Invasive Growth By Fungi?mentioning

confidence: 99%

Septins Focus Cellular Growth for Host Infection by Pathogenic Fungi

Momany

Talbot

2017

Front. Cell Dev. Biol.

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“…The number of septin genes varies widely between eukaryotic organisms, from 2 in nematodes to 13 in humans (25)(26)(27). Despite this variability, single particle electron microscopy and crystallography studies have shown that septins assemble into a conserved rodshaped heteromeric complex (also referred to as a protofilament) (Fig.…”

mentioning

confidence: 99%

Septin Form and Function at the Cell Cortex

Bridges

Gladfelter

2015

Journal of Biological Chemistry

131

138

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Septins are a conserved family of cytoskeletal GTP-binding proteins that function in cytokinesis, cell polarity, and membrane remodeling in many eukaryotic cell types (1, 2). To contribute to these diverse process, septins polymerize into filaments and higher-order structures that organize the cell cortex into domains that are tightly controlled in time and/or space (3). Higher-order septin structures act to recruit and/or integrate protein networks at specific locations, an example being contractile ring components in cell division (4 -7). In addition, septins are thought to alter lateral diffusion of proteins embedded in the plasma and endoplasmic reticulum (ER) 2 membranes and may influence local lipid composition (8 -10). In addition to membrane association, septins interact with, respond to, and organize the actin and microtubule cytoskeletons (11). Although septins were discovered by Hartwell, Pringle, and colleagues (12) in cell division cycle screens decades ago, understanding of septins has lagged behind other cytoskeletal systems. Recent biochemical, structural, and biophysical approaches, however, have made septins highly tractable and brought about exciting advances. Despite this recent progress, many fundamental questions remain in the septin field, in particular, the mechanisms by which septins associate with and influence the cell cortex.

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“…Therefore, studies addressing the question of their assembly into possible homofilamentous assemblies, similar to those composed of multiple subunits, could be very informative. Thus far, only one report addresses this issue using a non-flagellate green alga (17). Their results show this unique septin to be localized within a ringlike structure in vivo and to be involved in cytokinesis.…”

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confidence: 96%

“…Their results show this unique septin to be localized within a ringlike structure in vivo and to be involved in cytokinesis. Furthermore, recombinantly expressed protein was capable of forming filamentous structures in vitro, implying that filaments composed of a single septin may play important physiological roles in some species (17).…”

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confidence: 99%

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

Pinto

Pereira

Zeraik

et al. 2017

Journal of Biological Chemistry

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Edited by Norma AllewellSeptins are filament-forming GTP-binding proteins involved in many essential cellular events related to cytoskeletal dynamics and maintenance. Septins can self-assemble into heterocomplexes, which polymerize into highly organized, cell membraneinteracting filaments. The number of septin genes varies among organisms, and although their structure and function have been thoroughly studied in opisthokonts (including animals and fungi), no structural studies have been reported for other organisms. This makes the single septin from Chlamydomonas (CrSEPT) a particularly attractive model for investigating whether functional homopolymeric septin filaments also exist. CrSEPT was detected at the base of the flagella in Chlamydomonas, suggesting that CrSEPT is involved in the formation of a membrane-diffusion barrier. Using transmission electron microscopy, we observed that recombinant CrSEPT forms long filaments with dimensions comparable with those of the canonical structure described for opisthokonts. The GTP-binding domain of CrSEPT purified as a nucleotide-free monomer that hydrolyzes GTP and readily binds its analog guanosine 5-3-O-(thio)triphosphate. We also found that upon nucleotide binding, CrSEPT formed dimers that were stabilized by an interface involving the ligand (G-interface). Across this interface, one monomer supplied a catalytic arginine to the opposing subunit, greatly accelerating the rate of GTP hydrolysis. This is the first report of an arginine finger observed in a septin and suggests that CrSEPT may act as its own GTP-activating protein. The finger is conserved in all algal septin sequences, suggesting a possible correlation between the ability to form homopolymeric filaments and the accelerated rate of hydrolysis that it provides.

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Localization and evolution of septins in algae

Cited by 24 publications

References 42 publications

Septins Focus Cellular Growth for Host Infection by Pathogenic Fungi

Septins Focus Cellular Growth for Host Infection by Pathogenic Fungi

Septin Form and Function at the Cell Cortex

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

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