Cysteine is potentially toxic and can affect diverse functions such as oxidative stress, antibiotic resistance, and swarming motility. The contribution of cysteine catabolism in modulating responses to cysteine has not been examined, in part because the genes have not been identified and mutants lacking these genes have not been isolated or characterized. We identified the gene for a previously...

In all previous studies, bloodstream forms of Trypanosoma brucei could be grown in vitro only when supported by a feeder layer of mammalian fibroblasts. We have axenically cultivated bloodstream T. brucei by adding L-cysteine at regular intervals and appropriate concentrations. The optimum cysteine concentration depends on cell density and is close to physiological serum levels. At concentratio...

The role of cysteine residues in the Na(+)/dicarboxylate co-transporter (NaDC-1) was tested using site-directed mutagenesis. The transport activity of NaDC-1 was not affected by mutagenesis of any of the 11 cysteine residues, indicating that no individual cysteine residue is necessary for function. NaDC-1 is sensitive to inhibition by the impermeant cysteine-specific reagent, p-chloromercuriben...

Three stages can be distinguished in the temperature-induced mycelial-to-yeast phase transition of Histoplasma capsulatum. Stage one is characterized by a progressive decrease in the respiration rate and in the intracellular concentrations of cysteine and other amino acids. By stage two, respiration has ceased completely and free cysteine has fallen to low levels. Exogenous cysteine is required...

Because naïve T cells are unable to import cystine due to the absence of cystine transporters, it has been suggested that T cell activation is dependent on cysteine generated by antigen presenting cells. The aim of this study was to determine at which phases during T cell activation exogenous cystine/cysteine is required and how T cells meet this requirement. We found that early activation of T...

Medical literature indicates clearly that cystinuria and cystinosis, two severe genetic pathologies, are related to the presence of abnormal L-cystine deposits. While adopts a hexagonal crystal morphology consistent with its crystallographic structure (hexagonal, P6 1 22 space group), deposits cystinosis display rectangular shape. Because this is unexpected from L-cystine, we have investigated ...

Transported l-[(35)S]cysteine was rapidly metabolized by cultured tobacco cells when supplied to the cells at 0.02 millimolar or 0.5 millimolar. The internal cysteine pool was expandable to approximately 2400 nmoles per gram fresh weight.The (35)S label derived from cysteine was found in several metabolites. The amount of label in glutathione and sulfate was directly proportional to the interna...

A cysteine desulfhydrase was purified 110-fold from the green alga Chlorella using conven­ tional techniques. The isolated cysteine desulfhydrase was specific for D-cysteine having no activity towards L-cysteine. Dand L-cysteine desulfhydrase activities can be separated using DEAE-cellulose chromatography techniques. The isoelectric point o f this enzyme was deter­ mined to be around a pH o f 4...

Although essential amino acids regulate mechanistic target of rapamycin complex 1 (mTORC1) and the integrated stress response (ISR), the role of cysteine is unknown. We found that in hepatoma HepG2 cells, cystine (oxidized form of cysteine) activated mTORC1 and suppressed the ISR. Cystine deprivation induced GSH efflux and extracellular degradation, which aimed to restore cellular cysteine. Inh...

An early blocked sulfur amino acid auxotroph, Cephalosporium acremonium mutant 274-1 (which could be satisfied by methionine or cysteine), utilized organic sulfur compounds for cephalosporin C production in the following order of decreasing effectiveness; methionine > cystathionine > cysteine, despite the fact that cysteine is considered to be the immediate precursor of the antibiotic. When a g...