Biology subjects

Ndeh, R.

Publications and source records attributed to Ndeh, R..

3 recordsLinked to original sources

bioRxiv2026

Overexpression of flavodiiron protein Flv3 in engineered Synechocystis stimulates sucrose production and growth by altering cellular redox balance through enhanced sulfur metabolism

Biotechnological applications of oxygenic photosynthetic organisms depend on conversion of light energy into chemical energy through photosystems (PS). This energy can then be used to drive engineered metabolic pathways that are designed as strong electron sinks. For optimal performance, the engineered host metabolism must also be balanced with the native photoprotective electron transfer network. This includes the energy-consuming function of flavodiiron (Flv) proteins, which are universal to cyanobacteria and all other oxygenic photosynthetic organisms except angiosperms. In the cyanobacterium Synechocystis sp. PCC 6803, four different Flv proteins have been shown to function in a Mehler-like reaction within two heterodimeric forms (Flv1/Flv3 and Flv2/Flv4), donating electrons to O2 without generating oxidative stress. Previously, deleting Flv3 in the Synechocystis sucrose-producing (S02) strain was shown to cause drastic metabolic changes in S02{Delta}flv3, shifting it from photoautotrophic to mixotrophic growth (Muth-Pawlak, et al., 2024). In this study, we took an opposite approach by complementing S02 with Flv3 overexpression at different levels using RBS tuning. Interestingly, this resulted in S02oeFlv3 strains with significantly increased overall photosynthetic activity and sucrose production, enhanced cell growth, and storage compound accumulation. However, these outcomes are shown not to be due to conventional O2 photoreduction activity catalysed by Flv1/Flv3. Instead, we postulate that the observed changes are linked to the previously unidentified function of homomeric Flv3/Flv3 and the strongly increased sulphate redox metabolism. Based on extensive proteomic and metabolite analyses, we hypothesise that the Flv3 homooligomer uses sulfate metabolites directly or indirectly as the final electron acceptor instead of O2. This would also explain the upregulation of sulfate-related enzymes, as well as SQR, which passes the electrons back to the PQ pool in the Flv3 overexpression strain.

biochemistry↗

bioRxiv2022

DNA methyltransferase inhibition induces dynamic gene expression changes in lung CD4+ T cells of neonatal mice with E. coli pneumonia

IntroductionBacterial pulmonary infections are a major cause of morbidity and mortality in neonates, with less severity in older children. Previous studies demonstrated that the DNA of CD4+ T cells in the mouse lung, whose primary responsibility is to coordinate the immune response foreign pathogens, is differentially methylated in neonates compared with juveniles. Nevertheless, the effect of this differential DNA methylation on CD4+ T cell gene expression and response to infection remains unclear. MethodsWe treated E. coli-infected neonatal (4-day-old) and juvenile (13-day-old) mice with decitabine (DAC), a DNA methyltransferase inhibitor with broad-spectrum DNA demethylating activity, and performed simultaneous genome-wide DNA methylation and transcriptional profiling on lung CD4+ T cells. ResultsJuvenile and neonatal mice experienced differential demethylation in response to DAC treatment, with larger methylation differences observed in neonates. By cross-filtering differentially expressed genes between juveniles and neonates with those sites that were demethylated in neonates, we found that interferon-responsive genes such as Ifit1 are the most down-regulated methylation-sensitive genes in neonatal mice. DAC treatment shifted neonatal lung CD4+ T cells toward a gene expression program similar to that of juveniles. ConclusionFollowing lung infection with E. coli, lung CD4+ T cells in neonatal mice exhibit epigenetic repression of important host defense pathways, which are activated by inhibition of DNA methyltransferase activity to resemble a more mature profile.

immunology↗

bioRxiv2022

Cellular and molecular dynamics in the lungs of neonatal and juvenile mice in response to E. coli

Bacterial pneumonias cause significantly higher morbidity and mortality in neonates compared to other age groups. To understand the immune mechanisms that underlie these age-related differences, we employed a mouse model of E. coli pneumonia to examine cellular and molecular dynamics in immune responsiveness in neonates (PND 3-5) and juveniles (PND 12-18) at 24, 48, and 72 hours. Cytokine gene expression from whole lung extracts was quantified using qRT-PCR. E. coli challenge resulted in rapid and significant increases in neutrophils, monocytes, and y{delta}T cells and significant decreases in dendritic cells and alveolar macrophages for both neonates and juveniles. Juveniles had significant increases in interstitial macrophages and recruited monocytes that were not observed in neonatal lungs. Expression of IFN{gamma}-responsive genes were positively correlated with the levels and dynamics of MHCII-expressing innate cells in neonatal and juvenile lungs. Several facets of the responses of wild-type neonates was recapitulated in juvenile MHCII-/- juveniles. Employing a pre-clinical model of E. coli pneumonia, we identified significant differences in the early cellular and molecular dynamics in the lungs that likely contribute to the elevated susceptibility of neonates to bacterial pneumonia and could represent targets for intervention to improve respiratory outcomes and survivability of neonates.

immunology↗