Metabolism of L-[sulfane-34S]thiocystine by Escherichia coli

Abstract

The metabolism of L-thiocystine [bis(2-amino-2-carboxyethyl) trisulfide] by Escherichia coli was studied by using L-[sulfane-35S]thiocystine. This compound was found to serve as a source of sulfur for E. coli grown on a defined medium free of other sulfur sources and to incorporate its labeled sulfur into cysteine as well as the other sulfur-containing cellular components. For determination of the extent of the synthesis of new cysteine in these cells, cells were grown with [3,3-2H2]serine and L-[sulfane-34S]thiocystine, and the extent of incorporation of both deuterium and 34S into the cellular cysteine was measured by gas chromatography-mass spectrometry. The results show that approximately 50% of the cysteine which is incorporated into cellular macromolecules is derived from the thiocystine without cleavage of the carbon-sulfur bond, the remaining portion being newly biosynthesized from serine and 34S-enriched H2S. These results suggest that the first step in the metabolism of thiocystine by E. coli involves the beta elimination of pyruvate. This type of reaction is characteristic of the cleavage reactions catalyzed by beta-cystathionase.

Biotin Synthase: Purification, Characterization as a [2Fe-2S]Cluster Protein, and in vitro Activity of the Escherichia coli bioB Gene Product

“…There is also a possibility that AdoMet is the sulfur donor in the biotin synthase reaction. However, prior evidence indicates the sulfur in methionine (the obligatory precursor of AdoMet) is not the source of sulfur in the biotin synthase reaction in E. coli (Demoll & Shive, 1983; White, 1982), so on this evidence it seems unlikely that AdoMet is the sulfur donor. If AdoMet is not the sulfur donor, it could be involved in the activation of the enzyme.…”

“…Little is known about the mechanism of this reaction. The source of the sulfur atom is not known (Demole & Shive, 1983; White, 1982;Nimura et al, 1964). Parry's group has shown that except for the two protons that are removed in this reaction to accommodate the addition of sulfur, all the other protons on the two carbons to which the sulfur is added and the carbon-bound protons on the imidazole ring are preserved (Parry, 1983).…”

Determination of the metabolic origins of the sulfur and 3'-nitrogen atoms in biotin of Escherichia coli by mass spectrometry

“…Roberts et al (1955) also reported that the sulfur derived from a variety of sources including S042', S032", HS", L-cystine, DL-lanthionine, 5-methylcysteine, or glutathionine provided maximum potential growth. We reported that L-thiocystme can be a good sulfur source for E. coli (DeMoll & Shive, 1983), and White (1982) has presented evidence that approximately half of each type of the sulfur atoms of L-thiocystine are cycled through de novo synthesized cysteine. While E. coli may be able to use a variety of exogenous sulfur sources, the internal sulfur reservoirs in the organism have been shown to consist almost entirely of cysteine and methionine in protein and glutathione (Roberts et al, 1955).…”

“…Also, it was determined that all of the sulfur atoms of thiocystine [bis(2-amino-2-carboxyethyl) trisulfide] contribute approximately equally toward biotin biosynthesis. White (1982) has shown that both types of the sulfur atoms of thiocystine are eventually cycled through cysteine when the former is used as the sole sulfur source for the growth of the organism. Evidence has been presented that once transported into the organism, cystine is metabolized by both direct reduction to cysteine and by ß-elimination to yield thiocysteine, pyruvate, and ammonia (White, 1983).…”

Overexpression and Activity Analysis of Cystathionine γ-Lyase Responsible for the Biogenesis of H2S Neurotransmitter

“…또한, His-TEV-hCGL는 기질과의 반응에 영향을 미치 지 않음을 알 수 있었으며, His-TEV-hCGL이 cysteine을 분해 하여 H2S 기체를 만드는 것을 확인할 수 있었다. 단 control 를 포함한 모든 lane에 존재하는 hCGL의 아래 두 개의band 는 과발현에 사용한 E.coli유래의 cysteine 대사 관련 단백질인 cysteine synthetase일 가능성이 높다고 사료된다 [22,23].…”