Ubiquitination/deubiquitination pathways are now recognized as key components of gene regulatory mechanisms in eukaryotes. The major transcriptional repressor for carbon catabolite repression in Aspergillus nidulans is CreA, and mutational analysis led to the suggestion that a regulatory ubiquitination/deubiquitination pathway is involved. A key unanswered question is if and how this pathway, comprising CreB (deubiquitinating enzyme) and HulA (ubiquitin ligase) and other proteins, is involved in the regulatory mechanism. Previously, missense alleles of creA and creB were analysed for genetic interactions, and here we extended this to complete loss-of-function alleles of creA and creB, and compared morphological and biochemical phenotypes, which confirmed genetic interaction between the genes. We investigated whether CreA, or a protein in a complex with it, is a direct target of the CreB deubiquitination enzyme, using co-purifications of CreA and CreB, first using strains that overexpress the proteins and then using strains that express the proteins from their native promoters. The Phos-tag system was used to show that CreA is a phosphorylated protein, but no ubiquitination was detected using anti-ubiquitin antibodies and Western analysis. These findings were confirmed using mass spectrometry, which confirmed that CreA was differentially phosphorylated but not ubiquitinated. Thus, CreA is not a direct target of CreB, and nor are proteins that form part of a stable complex with CreA a target of CreB. These results open up new questions regarding the molecular mechanism of CreA repressing activity, and how the ubiquitination pathway involving CreB interacts with this regulatory network.
In Aspergillus nidulans, carbon catabolite repression (CCR) is mediated by the global repressor protein CreA. The deubiquitinating enzyme CreB is a component of the CCR network. Genetic interaction was confirmed using a strain containing complete loss-of-function alleles of both creA and creB. No direct physical interaction was identified between tagged versions of CreA and CreB. To identify any possible protein(s) that may form a bridge between CreA and CreB, we purified both proteins from mycelia grown in media that result in repression or derepression. The purified proteins were analysed by LC/MS and identified using MaxQuant and Mascot databases. For both CreA and CreB, 47 proteins were identified in repressing and derepressing conditions. Orthologues of the co-purified proteins were identified in S. cerevisiae and humans. Gene ontology analyses of A. nidulans proteins and yeast and human orthologues were performed. Functional annotation analysis revealed that proteins that preferentially interact with CreA in repressing conditions include histones and histone transcription regulator 3 (Hir3). Proteins interacting with CreB tend to be involved in cellular transportation and organization. Similar findings were obtained using yeast and human orthologues, although the yeast background generated a number of other biological processes involving Mig1p which were not present in the A. nidulans or human background analyses. Hir3 was present in repressing conditions for CreA and in both growth conditions for CreB, suggesting that Hir3, or proteins interacting with Hir3, could be a possible target of CreB.
Background: 2019-nCoV has been declared by WHO as a global pandemic in March 2020. The present study was undertaken to find out the global as well as local prevalence, and death rate of COVID-19.Methods: A developed questionnaire was used in Khulna division of Bangladesh to record the percentages of people who were mask user, involved with different risk groups, harmed by socio-economic impacts of COVID-19, involved with the issue of government taking measures for controlling COVID-19. Some of the highly risk countries of the world were selected for recording the data.Results: As of October 20, 2020, we found USA, and Bangladesh at 1st and 17th position respectively in terms of global prevalence of COVID-19. We found Dhaka at 1st position in terms of division wise prevalence in Bangladesh. In terms of death rate of COVID-19, Mexico reported 10.10% death rate by securing 1st position. We recorded the data related with percentages of people who were involved with mask using and risk groups like hypertension, diabetes, respiratory illness, smoking; harmed by socio-economic impacts of COVID-19 that changed their lives, believers of different levels on government taking measures for controlling the spread of COVID-19 from Khulna division.Conclusions: The findings of this research work would certainly help the government of highly risk countries as well as Bangladesh to take appropriate measures to control COVID-19. Moreover, it will be helpful for the government of Bangladesh to take necessary steps to mitigate the socio-economic crises existing among the people.
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