Treatment of Human Sporotrichosis Caused by Sporothrix brasiliensis

We describe the successful treatment of a series of 30 zoonotic sporotrichosis cases from southern Brazil. Sporothrix brasiliensis was the species genotypically identified in all 25 confirmed cases. Five other cases were classified as probable, without laboratory confirmation, but with clinical and epidemiological data of cat-transmitted sporotrichosis. Two isolates were sequenced by translation elongation factor-1 alpha (EF1α) loci in order to compare their sequences, and both of them showed distinct genotypes from S. brasiliensis strains from other Brazilian states. Itraconazole (ITZ) or potassium iodide (KI) were the first choice treatment in 28 and 2 cases, respectively. Microdilution assay showed a wild-type profile of S. brasiliensis isolates to ITZ. However, a lack of clinical response occurred in 42% of cases, especially those treated with ITZ 100 mg/day, and treatment needed modifications, by either increased doses or antifungal combinations. Clinical cure required a mean of 187 days of treatment, which was dependent on the clinical form of the disease and age of patients. Therapy, including dosages and durations, for cutaneous forms of sporotrichosis requires re-evaluation, since cases caused by S. brasiliensis may influence treatment efficacy.

Protein homeostasis is maintained by proteasomes containing PSMB9 induced by EEF1A2 upon mitochondrial stress

Perturbed proteostasis and mitochondrial dysfunction are often associated with age-related diseases such as Alzheimer′s and Parkinson′s diseases. However, the link between them remains incompletely understood. Mitochondrial dysfunction causes proteostasis imbalance, and cells respond to restore proteostasis by increasing proteasome activity and molecular chaperons in yeast and C. elegans. Here, we demonstrate the presence of similar responses in humans. Mitochondrial dysfunction upregulates a small heat shock protein HSPB1 and an immunoproteasome subunit PSMB9 leading to an increase in proteasome activity. HSPB1 and PSMB9 are required to prevent protein aggregation upon mitochondrial dysfunction. Moreover, PSMB9 expression is dependent on a translation elongation factor EEF1A2, and PSMB9-containing proteasomes are located near mitochondria, enabling fast local degradation of aberrant proteins. Our findings put a step forward in understanding the stress response triggered by mitochondrial dysfunction, and may be useful for therapeutic strategies to prevent or delay the onset of age-related diseases and attenuate their progression.

Morphology, Phylogeny and Pathogenicity of Pestalotioid Species on Camellia oleifera in China

Tea-oil tree (Camellia oleifera) is an important edible oil woody plant with a planting area of over 3,800,000 hectares in southern China. Pestalotioid fungi are associated with a wide variety of plants worldwide along with endophytes, pathogens, and saprobes. In this study, symptomatic leaves of C. oleifera were collected from Guangdong, Guangxi, Hainan, Hunan, and Jiangsu Provinces and pestalotioid fungi are characterized based on combined sequence data analyses of internal transcribed spacer (ITS), beta tubulin (tub2), and translation elongation factor 1-alpha (tef-1α) coupled with morphological characteristics. As a result, seven species were confirmed, of which five species are described as new viz. N. camelliae-oleiferae, P. camelliae-oleiferae, P. hunanensis, P. nanjingensis, P. nanningensis, while the other two are reported as known species, viz., N. cubana and N. iberica. Pathogenicity assays showed that all species except for P. nanjingensis developed brown lesions on healthy leaves and P. camelliae-oleiferae showed stronger virulence.

Analysis of senescence-responsive stress fiber proteome reveals reorganization of stress fibers mediated by elongation factor eEF2 in HFF-1 cells

Stress fibers (SFs), which are actomyosin structures, reorganize in response to various cues to maintain cellular homeostasis. Currently, the protein components of SFs are only partially identified, limiting our understanding of their responses. Here we isolate SFs from human fibroblasts HFF-1 to determine with proteomic analysis the whole protein components and how they change with replicative senescence (RS), a state where cells decline in ability to replicate after repeated divisions. We found that at least 135 proteins are associated with SFs, and 63 of them are upregulated with RS, by which SFs become larger in size. Among them, we focused on eEF2 (eukaryotic translation elongation factor 2) as it exhibited upon RS the most significant increase in abundance. We show that eEF2 is critical to the reorganization and stabilization of SFs in senescent fibroblasts. Our findings provide a novel molecular basis for SFs to be reinforced to resist cellular senescence.

Morphology and Phylogeny of Gnomoniopsis (Gnomoniaceae, Diaporthales) from Fagaceae Leaves in China

Gnomoniopsis (Gnomoniaceae, Diaporthales) is a well-classified genus inhabiting leaves, branches and fruits of the hosts in three plant families, namely Fagaceae, Onagraceae and Rosaceae. In the present study, eighteen Gnomoniopsis isolates were obtained from diseased leaves of Fagaceae hosts collected from Fujian, Guangdong, Hainan, Henan, Jiangxi and Shaanxi provinces in China. Morphology from the cultures and phylogeny based on the 5.8S nuclear ribosomal DNA gene with the two flanking internally transcribed spacer (ITS) regions, the translation elongation factor 1-alpha (tef1) and the beta-tubulin (tub2) genes were employed to identify these isolates. As a result, seven species were revealed, viz. Gnomoniopsis castanopsidis, G. fagacearum, G. guangdongensis, G. hainanensis, G. rossmaniae and G. silvicola spp. nov, as well as a known species G. daii. In addition, G. daii was firstly reported on the host Quercus aliena.

Autophagy-competent mitochondrial translation elongation factor TUFM inhibits caspase-8-mediated apoptosis

Mitochondria support multiple cell functions, but an accumulation of dysfunctional or excessive mitochondria is detrimental to cells. We previously demonstrated that a defect in the autophagic removal of mitochondria, termed mitophagy, leads to the acceleration of apoptosis induced by herpesvirus productive infection. However, the exact molecular mechanisms underlying activation of mitophagy and regulation of apoptosis remain poorly understood despite the identification of various mitophagy-associated proteins. Here, we report that the mitochondrial translation elongation factor Tu, a mitophagy-associated protein encoded by the TUFM gene, locates in part on the outer membrane of mitochondria (OMM) where it acts as an inhibitor of altered mitochondria-induced apoptosis through its autophagic function. Inducible depletion of TUFM potentiated caspase-8-mediated apoptosis in virus-infected cells with accumulation of altered mitochondria. In addition, TUFM depletion promoted caspase-8 activation induced by treatment with TNF-related apoptosis-inducing ligand in cancer cells, potentially via dysregulation of mitochondrial dynamics and mitophagy. Importantly, we revealed the existence of and structural requirements for autophagy-competent TUFM on the OMM; the GxxxG motif within the N-terminal mitochondrial targeting sequences of TUFM was required for self-dimerization and mitophagy. Furthermore, we found that autophagy-competent TUFM was subject to ubiquitin-proteasome-mediated degradation but stabilized upon mitophagy or autophagy activation. Moreover, overexpression of autophagy-competent TUFM could inhibit caspase-8 activation. These studies extend our knowledge of mitophagy regulation of apoptosis and could provide a novel strategic basis for targeted therapy of cancer and viral diseases.

Cryptic Diversity in Cladosporium cladosporioides Resulting from Sequence-Based Species Delimitation Analyses

Cladosporium cladosporioides is an extremely widespread fungus involved in associations ranging from mutualistic to pathogenic and is the most frequently represented Cladosporium species in sequence databases, such as Genbank. The taxonomy of Cladosporium species, currently based on the integration of molecular data with morphological and cultural characters, is in frequent need of revision. Hence, the recently developed species delimitation methods can be helpful to explore cryptic diversity in this genus. Considering a previous study that reported several hypothetical species within C. cladosporioides, we tested four methods of species delimitation using the combined DNA barcodes internal transcribed spacers, translation elongation factor 1-α and actin 1. The analyses involved 105 isolates, revealing that currently available sequences of C. cladosporioides in GenBank actually represent more than one species. Moreover, we found that eight isolates from this set should be ascribed to Cladosporium anthropophilum. Our results revealed a certain degree of discordance among species delimitation methods, which can be efficiently treated using conservative approaches in order to minimize the risk of considering false positives.

Diphthamide promotes TOR signaling by increasing the translation of proteins in the TORC1 pathway

Diphthamide, a modification found only on translation elongation factor 2 (EF2), was proposed to suppress −1 frameshifting in translation. Although diphthamide is conserved among all eukaryotes, exactly what proteins are affected by diphthamide deletion is not clear in cells. Through genome-wide profiling for a potential −1 frameshifting site, we identified that the target of rapamycin complex 1 (TORC1)/mammalian TORC1 (mTORC1) signaling pathway is affected by deletion of diphthamide. Diphthamide deficiency in yeast suppresses the translation of TORC1-activating proteins Vam6 and Rtc1. Interestingly, TORC1 signaling also promotes diphthamide biosynthesis, suggesting that diphthamide forms a positive feedback loop to promote translation under nutrient-rich conditions. Our results provide an explanation for why diphthamide is evolutionarily conserved and why diphthamide deletion can cause severe developmental defects.