Identification ofBremia lactucaeandOidium neolycopersiciproteins extracted for intact spore MALDI mass spectrometric biotyping

Distinct proteomes and allergen profiles appear across the life-cycle stages of Alternaria alternata

BACKGROUND

Alternaria alternata is associated with allergic respiratory diseases, which can be managed with allergen extract-based diagnostics and immunotherapy. It is not known how spores and hyphae contribute to allergen content. Commercial allergen extracts are manufactured by extracting proteins without separating the different forms of the fungus.

OBJECTIVE

We sought to determine differences between spore and hyphae proteomes and how allergens are distributed in Aalternata.

METHODS

Data-independent acquisition mass spectrometry was used to quantitatively compare the proteomes of asexual spores (nongerminating and germinating) with vegetative hyphae.

RESULTS

We identified 4515 proteins in nongerminating spores, germinating spores, and hyphae; most known allergens are more abundant in nongerminating spores. On comparing significant protein fold-change differences between nongerminating spores and hyphae, we found that 174 proteins were upregulated in nongerminating spores and 80 proteins in hyphae. Among the spore proteins are ones functionally involved in cell wall synthesis, responding to cellular stress, and maintaining redox balance and homeostasis. On comparing nongerminating and germinating spores, 25 proteins were found to be upregulated in nongerminating spores and 54 in germinating spores. Among the proteins specific to germinating spores were proteases known to be virulence factors. One of the most abundant proteins in the spore proteome is sialidase, which has not been identified as an allergen but may be important in the pathogenicity of this fungus. Major allergen Alt a 1 is present at low levels in spores and hyphae and appears to be largely secreted into growth media.

CONCLUSIONS

Spores and hyphae express overlapping but distinct proteomes. Most known allergens are found more abundantly in nongerminating spores.

Tissue-specific signatures in tick cell line MS profiles

Background

The availability of tick in vitro cell culture systems has facilitated many aspects of tick research, including proteomics. However, certain cell lines have shown a tissue-specific response to infection. Thus, a more thorough characterization of tick cell lines is necessary. Proteomic comparative studies of various tick cell lines will contribute to more efficient application of tick cell lines as model systems for investigation of host-vector-pathogen interactions.

Results

Three cell lines obtained from a hard tick, Ixodes ricinus, and two from I. scapularis were investigated. A cell mass spectrometry approach (MALDI-TOF MS) was applied, as well as classical proteomic workflows. Using PCA, tick cell line MS profiles were grouped into three clusters comprising IRE/CTVM19 and ISE18, IRE11 and IRE/CTVM20, and ISE6 cell lines. Two other approaches confirmed the results of PCA: in-solution digestion followed by nanoLC-ESI-Q-TOF MS/MS and 2D electrophoresis. The comparison of MS spectra of the cell lines and I. ricinus tick organs revealed 29 shared peaks. Of these, five were specific for ovaries, three each for gut and salivary glands, and one for Malpighian tubules. For the first time, characteristic peaks in MS profiles of tick cell lines were assigned to proteins identified in acidic extracts of corresponding cell lines.

Conclusions

Several organ-specific MS signals were revealed in the profiles of tick cell lines.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3460-5) contains supplementary material, which is available to authorized users.

Identification of cisplatin-binding sites on the large cytoplasmic loop of the Na+/K+-ATPase

Cisplatin is the most widely used chemotherapeutic drug for the treatment of various types of cancer; however, its administration brings also numerous side effects. It was demonstrated that cisplatin can inhibit the Na⁺/K⁺-ATPase (NKA), which can explain a large part of the adverse effects. In this study, we have identified five cysteinyl residues (C452, C456, C457, C577, and C656) as the cisplatin binding sites on the cytoplasmic loop connecting transmembrane helices 4 and 5 (C45), using site-directed mutagenesis and mass spectrometry experiments. The identified residues are known to be susceptible to glutathionylation indicating their involvement in a common regulatory mechanism.