Publications by authors named "Abderrahim Malki"

During the 3 years following the emergence of the COVID-19 pandemic, the African continent, like other regions of the world, was substantially impacted by COVID-19. In Morocco, the COVID-19 pandemic has been marked by the emergence and spread of several SARS-CoV-2 variants, leading to a substantial increase in the incidence of infections and deaths. Nevertheless, the comprehensive understanding of the genetic diversity, evolution, and epidemiology of several viral lineages remained limited in Morocco.

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Article Synopsis
  • The primary cause of congenital hearing loss is mostly genetic, with the GJB2 gene being crucial across different ethnicities.
  • A study involving Sanger sequencing analyzed GJB2 in 17 deaf children from 13 families in Ivory Coast, discovering pathogenic variants in one family with two deaf children.
  • The identified variants included a known nonsense substitution and a new 7-base pair duplication, marking the first report of GJB2 involvement in congenital hearing loss within an Ivorian family.
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Chronic myeloid leukemia (CML) is a neoplastic disease of genetic origin resulting from clonal proliferation of hematopoietic stem cells (HSCs). The reciprocal translocation t(9;22)(q34;q11) is the main chromosomal abnormality involved in this pathology, usually detected by conventional cytogenetics. This article aims to investigate the epidemiological, cytogenetic, therapeutic, and clinical characteristics of Moroccan patients with CML.

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Background: COVID-19 patients usually present multiple comorbidities and complications associated with severe forms of SARS-CoV-2 infection. This study aimed to assess the risk factors and prevalence of comorbidities and complications contributing to the severity of COVID-19.

Methods: This meta-analysis was performed according to PRISMA guidelines.

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Background: The emergence of SARS-CoV-2 variants has significantly increased the number of cases of COVID-19 among vaccinated individuals, raising concerns about the effectiveness of current vaccines. The aim of this study was to analyze the SARS-CoV-2 infection risks after primary vaccination with BNT162b2, BBIBP-CorV, or ChAdOx1-nCOV-19 and after homologues and heterologous booster vaccinations with these vaccines, as well as the profiles of reinfected patients.

Methods: We analyzed retrospectively 1082 patients vaccinated or unvaccinated with BNT162b2, BBIBP-CorV, and/or ChAdOx1nCoV-19 vaccines to determine their SARS-CoV2 infection statuses using the reverse transcription-polymerase chain reaction (RT-PCR) in addition to their clinical features.

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The process of steroidogenesis plays a vital role in human physiology as it governs the biosynthesis of mineralocorticoids, glucocorticoids, and androgens. These three classes of steroid hormones are primarily produced in the adrenal and gonadal glands through steroidogenesis pathways. Initiated by the side chain cleavage of cholesterol (CLR), this process leads to the conversion of cholesterol into pregnenolone and isocaproic aldehyde.

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In Algeria, the data and research on the essential and toxic chemical elements in food are limited and insufficient; therefore, the present study focused on evaluating the essential and toxic elements content in different 11 brands with two types (tomato and oil) of canned tuna fish, consumed in Algeria in 2022, by inductively coupled plasma-optical emission spectrometer (ICP-OES), while mercury (Hg) levels were determined by cold vapor atomic absorption spectrophotometry, as well as estimate the probabilistic risk assessment. The elements in canned tuna fish commercialized for human consumption in Algeria were determined by ICP-OES methods, The results showed that the heavy metal concentration in the samples under study ranged from 49.11 to 289.

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This is an analytical cross-sectional study of coronavirus disease 2019 (COVID-19) based on data collected between 1 November 2020 and 31 March 2021 in Casablanca focusing on the disease's epidemiological status and risk factors. A total of 4569 samples were collected and analysed by reverse-transcription polymerase chain reaction (RT-PCR); 967 patients were positive, representing a prevalence of 21.2 % for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

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Aurora Kinase C (AURKC) is considered an important element in Chromosome Passenger Complex (CPC), its interaction with Inner Centromere Protein (INCENP) plays a critical role in the establishment and the recruitment of a stable CPC during spermatogenesis. Genetic variations of gene are susceptible to impact AURKC-INCENP interaction, which may affect CPC stability and predispose male subjects to macrozoospermia. In this study, we systematically applied computational approaches using different bioinformatic tools to predict the effect of missense SNPs reported on gene, we selected the deleterious ones and we introduced their corresponding amino acid substitutions on AURKC protein structure.

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R-spondin proteins are secreted agonists of canonical WNT/β-catenin signaling. Homozygous RSPO1 mutations cause a syndrome of 46,XX disorder of sexual development (DSD), palmoplantar keratoderma (PPK), and predisposition to squamous cell carcinoma. We report exome sequencing data of two 46,XX siblings, one with testicular DSD and the other with suspected ovotesticular DSD.

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Background: Male infertility is responsible for 50% of infertile couples. Thirty percent of male infertility is due to cytogenetic and genetic abnormalities. In Arab and North African populations, several studies have shown the association of these chromosomal abnormalities with male infertility.

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YajL is the closest Escherichia coli homolog of the Parkinsonism-associated protein DJ-1, a multifunctional oxidative stress response protein whose biochemical function remains unclear. We recently described the oxidative-stress-dependent aggregation of proteins in yajL mutants and the oxidative-stress-dependent formation of mixed disulfides between YajL and members of the thiol proteome. We report here that yajL mutants display increased protein sulfenic acids levels and that formation of mixed disulfides between YajL and its protein substrates in vivo is inhibited by the sulfenic acid reactant dimedone, suggesting that YajL preferentially forms disulfides with sulfenylated proteins.

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YajL is the closest Escherichia coli homolog of the Parkinsonism-associated protein DJ-1, a multifunctional oxidative stress response protein whose biochemical function remains unclear. We recently reported the aggregation of proteins in a yajL mutant in an oxidative stress-dependent manner and that YajL exhibits chaperone activity. Here, we show that YajL displays covalent chaperone and weak protein oxidoreductase activities that are dependent on its exposed cysteine 106.

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We report here that YajL is associated with ribosomes and interacts with many ribosomal proteins and that a yajL mutant of Escherichia coli displays decreased translation accuracy, as well as increased dissociation of 70S ribosomes into 50S and 30S subunits after oxidative stress.

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YajL is the closest prokaryotic homolog of the parkinsonism-associated protein DJ-1 (40% sequence identity and similar three-dimensional structure), a protein of unknown function involved in the cellular response to oxidative stress. We report here that a yajL mutant of Escherichia coli displays an increased sensitivity to oxidative stress. It also exhibits a protein aggregation phenotype in aerobiosis, but not in anaerobiosis or in aerobic cells overexpressing superoxide dismutase, suggesting that protein aggregation depends on the presence of reactive oxygen species produced by respiratory chains.

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We used preS2-S'-beta-galactosidase, a three domain fusion protein that aggregates extensively at 43 degrees C in the cytoplasm of Escherichia coli to search for multicopy suppressors of protein aggregation and inclusion bodies formation, and took advantage of the known differential solubility of preS2-S'-beta-galactosidase at 37 and 43 degrees C to develop a selection procedure for the gene products that would prevent its aggregation in vivo at 43 degrees C. First, we demonstrate that the differential solubility of preS2-S'-beta-galactosidase results in a lactose-positive phenotype at 37 degrees C as opposed to a lactose-negative phenotype at 43 degrees C. We searched for multicopy suppressors of preS2-S'-beta-galactosidase aggregation at 43 degrees C by selecting pink lactose-positive colonies on a background of white lactose-negative colonies after transformation of bacteria with an E.

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Escherichia coli contains two thioredoxins, Trx1 and Trx2, and a thioredoxin-like protein, YbbN, which presents a strong homology in its N-terminal part with thioredoxins, and possesses a 20kDa C-terminal part of unknown function. We reported previously that YbbN displays both protein oxido-reductase and chaperone properties in vitro. In this study, we show that an ybbN-deficient strain displays an increased sensitivity to thermal stress but not to oxidative stress, a normal redox state of its cellular proteins but a decreased expression of several cytoplasmic proteins, including EF-Tu, DnaK, GroEL, trigger factor and several Krebs cycle enzymes, suggesting that the chaperone properties of YbbN are more important in vivo than its redox properties.

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The acid stress chaperones HdeA and HdeB of Escherichia coli prevent the aggregation of periplasmic proteins at acidic pH. We show in this report that they also form mixed aggregates with proteins that have failed to be solubilized at acidic pH and allow their subsequent solubilization at neutral pH. HdeA, HdeB, and HdeA and HdeB together display an increasing efficiency for the solubilization of protein aggregates at pH 3.

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We cloned, expressed, and purified the hdeB gene product, which belongs to the hdeAB acid stress operon. We extracted HdeB from bacteria by the osmotic-shock procedure and purified it to homogeneity by ion-exchange chromatography and hydroxyapatite chromatography. Its identity was confirmed by mass spectrometry analysis.

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Escherichia coli contains two thioredoxins, Trx1 and Trx2, and a thioredoxin-like protein, YbbN, which presents a strong homology in its N-terminal part with thioredoxin 1 and 2. YbbN, however, does not possess the canonical Cys-x-x-Cys active site of thioredoxins, but instead a Ser-x-x-Cys site. In addition to Cys-38, located in the SxxC site, it contains a second cysteine, Cys-63, close to Cys-38 in the 3D model.

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We cloned, expressed, and purified the Escherichia coli yhbO gene product, which is an amino acid sequence homolog to the Bacillus subtilis general stress protein 18 (the yfkM gene product), the Pyrococcus furiosus intracellular protease PfpI, and the human Parkinson disease protein DJ-1. The gene coding for YhbO was generated by amplifying the yhbO gene from E. coli by polymerase chain reaction.

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We have recently identified RrmJ, the first encoded protein of the rrmJ-ftsH heat shock operon, as being the Um(2552) methyltransferase of 23S rRNA, and reported that rrmJ-deficient strains exhibit growth defects, reduced translation rates and reduced stability of 70S ribosomes. U2552 is an ubiquitously methylated residue. It belongs to the A loop of 23S RNA which is an essential component of the ribosome peptidyltransferase centre and interacts directly with aminoacyl(A)-site tRNA.

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We used preS2-S'-beta-galactosidase, a three-domain fusion protein that aggregates extensively at 43 degrees C in the cytoplasm of Escherichia coli, to search for multicopy suppressors of protein aggregation and inclusion body formation and took advantage of the known differential solubility of preS2-S'-beta-galactosidase at 37 and 43 degrees C to develop a selection procedure for the gene products that would prevent its aggregation in vivo at 43 degrees C. First, we demonstrate that the differential solubility of preS2-S'-beta-galactosidase results in a lactose-positive phenotype at 37 degrees C as opposed to a lactose-negative phenotype at 43 degrees C. We searched for multicopy suppressors of preS2-S'-beta-galactosidase aggregation by selecting pink lactose-positive colonies on a background of white lactose-negative colonies at 43 degrees C after transformation of bacteria with an E.

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Hsp31, the Escherichia coli hcha gene product, is a molecular chaperone whose activity is inhibited by ATP at high temperature. Its crystal structure reveals a putative Cys(184), His(185), and Asp(213) catalytic triad similar to that of the Pyrococcus horikoshii protease PH1704, suggesting that it should display a proteolytic activity. A preliminary report has shown that Hsp31 has an exceedingly weak proteolytic activity toward bovine serum albumin and a peptidase activity toward two peptide substrates with small amino acids at their N terminus (alanine or glycine), but the physiological significance of this observation remains unclear.

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We have cloned, purified to homogeneity, and characterized as a molecular chaperone the Escherichia coli YedU protein. The purified protein shows a single band at 31 kDa on SDS-polyacrylamide gels and forms dimers in solution. Like other chaperones, YedU interacts with unfolded and denatured proteins.

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