Anopheles aquasalis is a dipteran of the family Culicidae that is widely distributed in the coastal regions of South and Central America. This species acts as a vector of Plasmodium vivax, an ...important etiological agent of malaria, which represents a serious public health problem. In mosquitoes, trypsin-like serine proteases are important in blood meal digestion, immune responses and reproductive functions. The study of peptidases expressed in the mosquito midgut is essential to understanding the mechanisms of parasite-host interaction and the physiological process of nutrient digestion.
Our study aimed to identify and characterize the proteolytic activities in the midgut of sugar-fed An. aquasalis females using zymographic analyses (substrate-SDS-PAGE), in-solution assays and mass spectrometry.
Here, we used a zymographic analysis to further biochemically characterize the proteolytic profile of the midgut of sugar-feeding An. aquasalis females. The trypsin peptidases migrated between ~17 and ~76 kDa and displayed higher proteolytic activities between pH 7.5 and 10 and at temperatures between 37 °C and 50 °C. Four putative trypsin-like serine peptidases were identified using mass spectrometry and data mining. The molecular masses of these peptidases were similar to those observed using zymography, which suggested that these peptidases could be responsible for some of the observed proteolytic bands.
Taken together, our results contribute to the gene annotation of the unknown genome of this species, to the tissue location of these peptidases, and to the functional prediction of these crucial enzymes, which all impact further studies of this species.
The inability of the yeast
Saccharomyces cerevisiae
to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior studies reveal that functional ...expression of xylose isomerase (XI) from
Burkholderia cenocepacia
(XylA
Bc
) in
S. cerevisiae
has remarkably improved xylose consumption and ethanol productivity. Yet, little is known about kinetic and structural properties of this enzyme. Hereby, a purified recombinant XylA was assayed in vitro, showing optimal enzyme activity at 37 °C and pH 7.2. The K
m
of XylA for
d
-xylose was at least threefold lower than the K
m
results for any XI published to date (e.g. XylA from
Piromyces
sp.). In addition, oligomerization behavior as a tetramer was observed for XylA in solution. Functional and structural comparative analyses amongst three microbial XIs were further performed as theoretical models, showing that xylose orientation at the active site was highly conserved among the XIs. Mg
2+
ions anchor the sugar and guide its pyranoside oxygen towards a histidine residue present at the active site, allowing an acid–base reaction, linearizing xylose. Electrostatic surface analyses showed that small variations in the net charge distribution and dipole moment could directly affect the way the substrate interacts with the protein, thus altering its kinetic properties. Accordingly, in silico modeling suggested the tetramer may be the major functional form. These analyses and the resulting model promote a better understanding of this protein family and pave the way to further protein engineering and application of XylA in the ethanol industry.
Extracellular proteins secreted/released by protozoan parasites are key mediators of the host–parasite interaction. To characterise the profile of proteins secreted/released by
Leishmania (
Viannia)
...braziliensis promastigotes, a proteomic approach combining two-dimensional electrophoresis (2DE), tandem matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF/TOF) mass spectrometry, and data mining was carried out. The 2DE map revealed a set of 270 secreted protein spots from which 42 were confidently identified and classified into 11 categories according to Gene Ontology (GeneDB database) and KEEG Ontology annotation of biological processes. Parasite promastigotes were able to secrete/release proteins involved in immunomodulation, signal transduction, and intracellular survival, such as HSP70, acid phosphatase, activated protein kinase C receptor (LACK), elongation factor 1β, and tryparedoxin peroxidase. Data mining showed that ~
5% of identified proteins present a classical secretion signal whereas ~
57% were secreted following non-classical secretion mechanisms, indicating that protein export in this primitive eukaryote might proceed mainly by unconventional pathways. This study reports a suitable approach to identify secreted proteins in the culture supernatant of
L. braziliensis and provides new perspectives for the study of molecules potentially involved in the early stages of infection.
This study reports a suitable approach to identify secreted proteins of
Leishmania braziliensis and provides new perspectives for the study of molecules potentially involved in the early stages of infection.
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New robust and reproducible differentiation approaches are needed to generate induced pluripotent stem cell (iPSC)-derived cardiomyocytes of specific subtypes in predictable quantities for ...tissue-specific disease modeling, tissue engineering, and eventual clinical translation. Here, we assessed whether powdered decellularized extracellular matrix (dECM) particles contained chamber-specific cues that could direct the cardiac differentiation of human iPSCs toward an atrial phenotype. Human hearts were dissected and the left ventricle (LV) and left atria (LA) were isolated, minced, and decellularized using an adapted submersion decellularization technique to generate chamber-specific powdered dECM. Comparative proteomic analyses showed chamber-specific dECM segregation, with atrial- and ventricle-specific proteins uniquely present in powdered dECM-hA and dECM-hV, respectively. Cell populations differentiated in the presence of dECM-hA showed upregulated atrial molecular markers and a two-fold increase in the number of atrial-like cells as compared with cells differentiated with dECM-hV or no dECM (control). Finally, electrophysiological data showed an increase in action potentials characteristic of atrial-like cells in the dECM-hA group. These findings support the hypothesis that dECM powder derived from human atria retained endogenous cues to drive cardiac differentiation toward an atrial fate.
Although older adults are at a high risk of severe or critical Covid-19, there are many cases of unvaccinated centenarians who had a silent infection or recovered from mild or moderate Covid-19. We ...studied three Brazilian supercentenarians, older than 110 years, who survived Covid-19 in 2020 before being vaccinated.
Despite their advanced age, humoral immune response analysis showed that these individuals displayed robust levels of IgG and neutralizing antibodies (NAbs) against SARS-CoV-2. Enrichment of plasma proteins and metabolites related to innate immune response and host defense was also observed. None presented autoantibodies (auto-Abs) to type I interferon (IFN). Furthermore, these supercentenarians do not carry rare variants in genes underlying the known inborn errors of immunity, including particular inborn errors of type I IFN.
These observations suggest that their Covid-19 resilience might be a combination of their genetic background and their innate and adaptive immunity.
In the advanced stages, malignant melanoma (MM) has a very poor prognosis. Due to tremendous efforts in cancer research over the last 10 years, and the introduction of novel therapies such as ...targeted therapies and immunomodulators, the rather dark horizon of the median survival has dramatically changed from under 1 year to several years. With the advent of proteomics, deep-mining studies can reach low-abundant expression levels. The complexity of the proteome, however, still surpasses the dynamic range capabilities of current analytical techniques. Consequently, many predicted protein products with potential biological functions have not yet been verified in experimental proteomic data. This category of ‘missing proteins’ (MP) is comprised of all proteins that have been predicted but are currently unverified. As part of the initiative launched in 2016 in the USA, the European Cancer Moonshot Center has performed numerous deep proteomics analyses on samples from MM patients. In this study, nine MPs were clearly identified by mass spectrometry in MM metastases. Some MPs significantly correlated with proteins that possess identical PFAM structural domains; and other MPs were significantly associated with cancer-related proteins. This is the first study to our knowledge, where unknown and novel proteins have been annotated in metastatic melanoma tumour tissue.
The inner integument of Jatropha curcas seeds is a non-photosynthetic tissue that acts primarily as a conduit for the delivery of nutrients to the embryo and endosperm. In this study we performed a ...histological and transmission electron microscopy analysis of the inner integument in stages prior to fertilization to 25days after pollination, to establish the structural changes associated with the plastid to gerontoplast transition. This study showed that plastids are subjected to progressive changes, which include the dismantling of the internal membrane system, matrix degradation and the formation of stromule-derived vesicles. A proteome analysis of gerontoplasts isolated from the inner integument at 25days after pollination, resulted in the identification of 1923 proteins, which were involved in a myriad of metabolic functions, such as synthesis of amino acids and fatty acids. Among the identified proteins, were also a number of hydrolases (peptidases, lipases and carbohydrases), which presumably are involved in the ordered dismantling of this organelle to provide additional sources of nutrients for the growing embryo and endosperm. The dataset we provide here may provide a foundation for the study of the proteome changes associated with the plastid to gerontoplast transition in non-photosynthetic tissues.
We describe ultrastructural features of gerontoplasts isolated from the inner integument of developing seeds of Jatropha curcas, together with a deep proteome analysis of these gerontoplasts. This article explores a new aspect of the biology of plastids, namely the ultrastructural and proteome changes associated with the transition plastid to gerontoplast in a non-photosynthetic tissue.
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•Ultrastructural features of the transition plastid to gerontoplast;•Wide diversity of metabolite transporters in gerontoplasts;•Identification of several peptidases and lipases involved in the dismantling of plastids
Mass spectrometry has become indispensable for peptide and protein quantification in proteomics studies. When proteomics technologies are applied to understand the biology of plants, two-dimensional ...gel electrophoresis is still the prevalent method for protein fractionation, identification, and quantitation. In the present work, we have used LC-MS to compare an isotopic (ICPL) and isobaric (iTRAQ) chemical labeling technique to quantify proteins in the endosperm of Ricinus communis seeds at three developmental stages (IV, VI, and X). Endosperm proteins of each stage were trypsin-digested in-solution, and the same amount of peptides was labeled with ICPL and iTRAQ tags in two orders (forward and reverse). Each sample was submitted to nanoLC coupled to an LTQ-Orbitrap high-resolution mass spectrometer. Comparing labeling performance, iTRAQ was able to label 99.8% of all identified unique peptides, while 94.1% were labeled by ICPL. After statistical analysis, it was possible to quantify 309 (ICPL) and 321 (iTRAQ) proteins, from which 95 are specific to ICPL, 107 to iTRAQ, and 214 common to both labeling strategies. We noted that the iTRAQ quantification could be influenced by the tag. Even though the efficiency of the iTRAQ and ICPL in protein quantification depends on several parameters, both labeling methods were able to successfully quantify proteins present in the endosperm of castor bean during seed development and, when combined, increase the number of quantified proteins.
Aedes aegypti females ingest sugar or blood to obtain the nutrients needed to maintain cellular homeostasis. During human blood ingestion, female mosquitoes may transmit different viruses such as ...dengue, yellow fever and, more recently, zika and chikungunya. Here, we report changes in protein expression in the heads of adult female Ae. aegypti mosquitoes in response to the ingestion of blood or sugar. Proteins extracted from the heads of Ae. aegypti fed exclusively on blood (BF) or sugar (SF) were trypsin hydrolyzed (off‐gel) and analyzed by the reverse‐phase nano‐liquid chromatography coupled with hybrid mass spectrometry. A total of 1139 proteins were identified in female heads, representing 7.4% of the predicted proteins in Ae. aegypti genome (total = 15 419 active genes). Gene ontology annotation and categories showed that, in this insect, the head was rich in proteins involved in the metabolic process, proton transport, organelle, macromolecular complex, structural molecule activity, antioxidant activity, and catalytic activity. Our report is the first indicating that many of the annotated genes are translated into functional proteins in heads of adult female Ae. aegypti. Interestingly, we identified 8.7 times more exclusively expressed proteins involved in signal transduction, replication–transcription–translation (5.5 x), and transport (2.9 x) activity in BF than in SF groups. This paper discusses the protein profile of Ae. aegypti female heads and its implications for blood ingestion and carbohydrate intake.
Using histological analysis of the induction of secondary somatic embryogenesis (SSE) in cassava (
Manihot esculenta Crantz) as a guide, we performed 2-DE for protein separation and matrix-assisted ...laser desorption ionization-time of flight-tandem mass spectrometry (MALDI-TOF-TOF-MS) for protein identification in cotyledons of cassava somatic embryos undergoing SSE. Reference map obtained by 2-DE within a pH range of 3–10 and a size range of 6–97
kDa revealed approximately 410 eletrophoretically resolved spots populated primarily by acidic (p
I
<
7) proteins with molecular masses between 30 and 75
kDa. Tryptic digestion of 163 of the most abundant spots led to the identification of 86 proteins with a protein identification success rate of 53%. In total, 43% of the identified proteins were involved in metabolism and energy and 11.6% in protein destination and storage. Others are, disease/defense (11.6%), transcription and protein synthesis (7%), signal transduction (5.8%), cell growth/division (3.5%), transporters (3.5%), cell structure (2.3%), secondary metabolism (1.2%) and other functional classes (10.5%). Our studies demonstrate that 2-DE-based proteomic approaches combined with histological studies can serve as tools for identifying protein markers for the developmental stages of cassava SE while providing clues on the underlying causes of the low rate of conversion of cassava somatic embryos into mature plants.
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