Search results for "Corynebacterium glutamicum"

Relevance of NADH Dehydrogenase and Alternative Two-Enzyme Systems for Growth of Corynebacterium glutamicum With Glucose, Lactate, and Acetate

2021

The oxidation of NADH with the concomitant reduction of a quinone is a crucial step in the metabolism of respiring cells. In this study, we analyzed the relevance of three different NADH oxidation systems in the actinobacterial model organism Corynebacterium glutamicum by characterizing defined mutants lacking the non-proton-pumping NADH dehydrogenase Ndh (Δndh) and/or one of the alternative NADH-oxidizing enzymes, L-lactate dehydrogenase LdhA (ΔldhA) and malate dehydrogenase Mdh (Δmdh). Together with the menaquinone-dependent L-lactate dehydrogenase LldD and malate:quinone oxidoreductase Mqo, the LdhA-LldD and Mdh-Mqo couples can functionally replace Ndh activity. In glucose minimal medium…

2020

Lsr2-like nucleoid-associated proteins play an important role as xenogeneic silencers (XS) of horizontally acquired genomic regions in actinobacteria. In this study, we systematically analyzed the in vivo constraints underlying silencing and counter-silencing of the Lsr2-like protein CgpS in Corynebacterium glutamicum Genome-wide analysis revealed binding of CgpS to regions featuring a distinct drop in GC profile close to the transcription start site (TSS) but also identified an overrepresented motif with multiple A/T steps at the nucleation site of the nucleoprotein complex. Binding of specific transcription factors (TFs) may oppose XS activity, leading to counter-silencing. Following a sy…

Identification of Gip as a novel phage‐encoded gyrase inhibitor protein of Corynebacterium glutamicum

2021

By targeting key regulatory hubs of their host, bacteriophages represent a powerful source for the identification of novel antimicrobial proteins. Here, a screening of small cytoplasmic proteins encoded by the CGP3 prophage of Corynebacterium glutamicum resulted in the identification of the gyrase-inhibiting protein Cg1978, termed Gip. Pull-down assays and surface plasmon resonance revealed a direct interaction of Gip with the gyrase subunit A (GyrA). The inhibitory activity of Gip was shown to be specific to the DNA gyrase of its bacterial host C. glutamicum. Overproduction of Gip in C. glutamicum resulted in a severe growth defect as well as an induction of the SOS response. Furthermore, …

Deciphering the rules underlying xenogeneic silencing and counter-silencing of Lsr2-like proteins

2019

ABSTRACTLsr2-like nucleoid-associated proteins play an important role as xenogeneic silencers (XS) of horizontally acquired genomic regions in actinobacteria. In this study, we systematically analyzed the in vivo constraints underlying silencing and counter-silencing of the Lsr2-like protein CgpS inCorynebacterium glutamicum. Genome-wide analysis revealed binding of CgpS to regions featuring a distinct drop in GC-profile close to the transcription start site (TSS), but also identified an overrepresented motif with multiple A/T steps at the nucleation site of the nucleoprotein complex. Binding of specific transcription factors (TFs) may oppose XS activity leading to counter-silencing. Follow…

Lysine synthesis control in Corynebacterium glutamicum RC 115 in mixed substrate (glucose-acetate) medium.

2003

The effect of acetate as a glucose co-substrate on growth, lysine synthesis and experimental lysine yield from carbon substrates by Corynebacterium glutamicum RC 115 was investigated. It was found that low amounts of acetate, injected with a glucose-acetate pulse into the steady-state continuous culture in bioreactor, caused a slight decrease in the specific rates of glucose uptake and bacterial growth, but a significant increase in the cell specific rate of lysine synthesis and an increase in lysine yield. In contrast, acetate injected in high amounts was followed by a drastic decrease in the values of these parameters. A strong increase in experimental lysine yield under the latter condit…

Metabolic fluxes and l-lysine synthesis by Corynebacterium glutamicum in relation to cellular total reducing activity

2001

Abstract The total reducing activity (TRA) of cells was used to estimate the physiological activity of Corynebacterium glutamicum under conditions of l -lysine synthesis. This was estimated as the rate of reduction of 2,3,5- triphenyltetrazolium chloride by intact cells. TRA of cells was linearly correlated with the intracellular concentrations of RNA and the bacterial growth rate. It was concluded that this activity reflected the rate of energy generation in cells. A decrease in TRA of growing cells was related to an increase in bacterial lysine synthesis activity. Alteration in metabolic pathway functioning and an increase in the intracellular concentrations of lysine precursors favoured …

Deciphering the Rules Underlying Xenogeneic Silencing and Counter-Silencing of Lsr2-like Proteins Using CgpS of Corynebacterium glutamicum as a Model

2020

In actinobacteria, Lsr2-like nucleoid-associated proteins function as xenogeneic silencers (XS) of horizontally acquired genomic regions, including viral elements, virulence gene clusters in Mycobacterium tuberculosis, and genes involved in cryptic specialized metabolism in Streptomyces species. Consequently, a detailed mechanistic understanding of Lsr2 binding in vivo is relevant as a potential drug target and for the identification of novel bioactive compounds. Here, we followed an in vivo approach to investigate the rules underlying xenogeneic silencing and counter-silencing of the Lsr2-like XS CgpS from Corynebacterium glutamicum. Our results demonstrated that CgpS distinguishes between…

Identification and expression of the 11β‐steroid hydroxylase from Cochliobolus lunatus in Corynebacterium glutamicum

2019

Hydroxylation of steroids has acquired special relevance for the pharmaceutical industries. Particularly, the 11β-hydroxylation of steroids is a reaction of biotechnological importance currently carried out at industrial scale by the fungus Cochliobolus lunatus. In this work, we have identified the genes encoding the cytochrome CYP103168 and the reductase CPR64795 of C. lunatus responsible for the 11β-hydroxylase activity in this fungus, which is the key step for the preparative synthesis of cortisol in industry. A recombinant Corynebacterium glutamicum strain harbouring a plasmid expressing both genes forming a synthetic bacterial operon was able to 11β-hydroxylate several steroids as subs…

In Vitro Analysis of the Two-Component System MtrB-MtrA from Corynebacterium glutamicum▿ †

2007

ABSTRACT The two-component system MtrBA is involved in the osmostress response of Corynebacterium glutamicum . MtrB was reconstituted in a functionally active form in liposomes and showed autophosphorylation and phosphatase activity. In proteoliposomes, MtrB activity was stimulated by monovalent cations used by many osmosensors for the detection of hypertonicity. Although MtrB was activated by monovalent cations, they lead in vitro to a general stabilization of histidine kinases and do not represent the stimulus for MtrB to sense hyperosmotic stress.

Metabolism and Lysine Biosynthesis Control in Brevibacterium Flavum: Impact of Stringent Response in Bacterial Cells

2005

Parameters affecting lysine biosynthesis by Brevibacterium flavum RC 115 cells under stringent response conditions (test guanosine 5′-diphosphate 3′-diphosphate accumulation in cells) caused by threonine limitation were investigated. Experimental results confirmed that an increase in lysine biosynthesis by this bacterium under stringent response conditions might be a result of an increase in the intracellular concentration of NADPH as well as lysine export activity.