l-cysteine is an important sulfur-containing α-amino acid. It exhibits multiple physiological functions with diverse applications in pharmaceutical cosmetics and food industry. Here, a strategy of coordinated gene expression between carbon and sulfur modules in Escherichia coli was proposed and conducted for the production of l-cysteine. Initially, the titer of l-cysteine was improved to (0.38±0.02) g/L from zero by enhancing the biosynthesis of l-serine module (serA^f, serB and serC^Cg) and overexpression of CysB. Then, promotion of l-cysteine transporter, increased assimilation of sulfur, reduction or deletion of l-cysteine and l-serine degradation pathway and enhanced expression of cysE^f (encoding serine acetyltransferase) and cysB^St (encoding transcriptional dual regulator CysB) were achieved, resulting in an improved l-cysteine titer (3.82±0.01) g/L. Subsequently, expressions of cysM, nrdH, cysK and cysIJ genes that were involved in sulfur module were regulated synergistically with carbon module combined with utilization of sulfate and thiosulfate, resulting in a strain producing (4.17±0.07) g/L l-cysteine in flask shake and (11.94±0.1) g/L l-cysteine in 2 L bioreactor. Our results indicated that efficient biosynthesis of l-cysteine could be achieved by a proportional supply of sulfur and carbon in vivo. This study would facilitate the commercial bioproduction of l-cysteine.
Escherichia coli/metabolism* ; Cysteine/metabolism* ; Bioreactors ; Sulfur/metabolism* ; Serine/metabolism*

Based on our studies for more than 20 years, we review the recent advances in sulfur dioxide (SO2) biology. Three sections are involved: (1) The studies on SO2 toxicological effects and its underlying mechanisms; (2) The new investigations on SO2 donor and physiological role of SO2 as a new type-gas transmitter; (3) The observations on pathophysiologic roles of SO2.
Animals ; Humans ; Physiological Phenomena ; Sulfur Dioxide ; metabolism ; toxicity

The ubiquitin-related modifier Urm1 can be covalently conjugated to lysine residues of other proteins, such as yeast Ahp1 and human MOCS3, through a mechanism involving the E1-like protein Uba4 (MOCS3 in humans). Similar to ubiquitination, urmylation requires a thioester intermediate and forms isopeptide bonds between Urm1 and its substrates. In addition, the urmylation process can be significantly enhanced by oxidative stress. Recent findings have demonstrated that Urm1 also acts as a sulfur carrier in the thiolation of eukaryotic tRNA via a mechanism that requires the formation of a thiocarboxylated Urm1. This role is very similar to that of prokaryotic sulfur carriers such as MoaD and ThiS. Evidence strongly supports the hypothesis that Urm1 is the molecular fossil in the evolutionary link between prokaryotic sulfur carriers and eukaryotic ubiquitin-like proteins. In the present review, we discuss the dual role of Urm1 in protein and tRNA modification.
Animals ; Humans ; Models, Biological ; RNA, Transfer ; metabolism ; Sulfur ; metabolism ; Ubiquitin ; metabolism ; Ubiquitins ; metabolism

Bacterial Proteins ; metabolism ; Carbon-Sulfur Lyases ; metabolism ; Mouth ; microbiology ; Quorum Sensing ; Signal Transduction

Hydrogenases are enzymes that catalyse the oxidation of hydrogen and the reduction of protons. It plays an important role in the process of biohydrogen production. According to the metal atoms within hydrogenase, it can be classified as NiFe-hydrogenase, Fe-hydrogenase and metal-free hydrogenase. The overwhelming majority of hydrogenases are metalloenzymes. The metal atoms are involved in the forming of active site and [Fe-S] clusters. The active site directly catalyzes the reduction of protons and the oxidation of hydrogen. The [Fe-S] clusters are involved in the transport of electrons between the H2-activating site and the redox partners of hydrogenase. Presently, the crystal structures of NiFe-hydrogenase and Fe-hydrogenase from a few kinds of microorganism have been revealed. The metal-free hydrogenase, characterized by the absence of [Fe-S] cluster and the presence of an iron-containing cofactor, shows a great diversity comparing with those of NiFe-hydrogenases and Fe-hydrogenases. Recent progress have also indicated the mechanisms of activation.
Catalysis ; Catalytic Domain ; Hydrogenase ; metabolism ; Iron-Sulfur Proteins ; metabolism ; Oxidation-Reduction

OBJECTIVEThis review summarized the current advances in understanding the role of the novel gasotransmitter, sulfur dioxide (SO2), in the cardiovascular system.

DATA SOURCESArticles on the advances in the study of the role of endogenous sulfur dioxide in the cardiovascular system were accessed from PubMed and CNKI from 2003 to 2013, using keywords such as "endogenous sulfur dioxide" and "cardiovascular system".

STUDY SELECTIONArticles with regard to the role of SO2 in the regulation of cardiovascular system were selected.

RESULTSRecently, scientists discovered that an endogenous SO2 pathway is present in the cardiovascular system and exerts physiologically significant effects, such as regulation of the cardiac function and the pathogenesis of various cardiopulmonary diseases such as hypoxic pulmonary hypertension, hypertension, coronary atherosclerosis, and cardiac ischemia-reperfusion (I/R) injury, in the cardiovascular system.

CONCLUSIONSEndogenous SO2 is a novel member of the gasotransmitter family in addition to the nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S). Studies indicated that it has a role in regulating the cardiovascular disease.

Animals ; Cardiovascular Diseases ; metabolism ; pathology ; Cardiovascular System ; metabolism ; pathology ; Humans ; Hydrogen Sulfide ; metabolism ; Nitric Oxide ; metabolism ; Sulfur Dioxide ; metabolism

We studied the hydrogen evolution (HE) of green alga Chlorella pyrenoidosa grown in normal (nutrients sufficient) media and nitrogen, manganese or sulfur deprived medium. The results showed that photo-hydrogen evolution could occur under all conditions herein before, but the efficiency of HE was maximum under nitrogen deprivation, and the total hydrogen yield was 88.613 microL H2/mg Chla, which was 4.61, 1.92, 3.63 times of control, manganese deprivation, sulfur deprivation groups, respectively. We also measured the growth, the photosynthesis and respiration of the alga. The data demonstrated that manganese deprivation had less influence than nitrogen and sulfur deprivation on the growth, the photosynthesis and respiration of C. pyrenoidosa. Compared with the normal (nutrients sufficient), manganese and sulfur deprivation inhibited the photosynthesis and growth of the alga while bringing small impact on respiration. Nitrogen deprivation, however, greatly restrained the photosynthesis and growth while enhancing the respiration. Those data provide clues for the further study on both the conditions optimization and mechanism of hydrogen evolution.
Chlorella ; growth & development ; metabolism ; Hydrogen ; analysis ; metabolism ; Manganese ; analysis ; metabolism ; Nitrogen ; analysis ; metabolism ; Photosynthesis ; Sulfur ; analysis ; metabolism

Lactic dehydrogenase (LDH) isozyme pattens were examined in rats after exposing the animal to 250 ppm of sulfur dioxide gas. The isozymes of the respective tissues were separated on cellulose-acetate strips from the brain, lung, heart, liver, kidneys, and muscle, and visualized as the isozyme bands by the formazan reaction and analyzed by densitometry. As well as the above experiment, room-air and room-air+SO2 were aerated through tissue homoenates in-vitro, accompanied by pure oxygen aeration in order to see the in vitro effect of the gases on the LDH activity in the tissues mentioned with the following conclusions. (1) The H-type of LDH activity dominated in the normal heart tissue of rats, M-type in the normal lung, liver, and muscle tissues of the animal. (2) The kidney tissue of normal rats exhibited preponderance of LDH-1 and-5 isozymes, brain tissue in LDH-1 and-4 isozymes. (3) When rats inhaled sulfur dioxide gas in the concentration of 250 ppm, it appeared that the M-type tended to predominate in the anaerobic tissues and the H-type in the aerobic tissue. (4) The degree of oxygen tension seemed to be correlated with the low level of LDH activity in the anaerobic tissues such as liver and muscle and with the increased activity in the aerobic tissues, such as heart and lung. (5) The low oxygen tension seems to favor syn-thesis of M-type LDH and high oxygen tesnion H-type LDH in the tissues of rats.
Air Pollution ; Animal ; Citric Acid Cycle ; Densitometry ; Electrophoresis ; Environmental Exposure ; Isoenzymes ; Lactate Dehydrogenase/metabolism* ; Oxygen/metabolism ; Rats ; Sulfur Dioxide/toxicity* ; Substances: ; Isoenzymes ; Sulfur Dioxide ; Oxygen ; Lactate Dehydrogenase

OBJECTIVETo observe the cell binding characteristics of SonoVue microbubbles targeting choriocarcinoma cells and provide evidence for clinical ultrasonic localization of the tumor utilizing the microbubbles.

METHODSThe targeted microbubbles were prepared by conjugating anti-HCG antibody with the SonoVue microbubbles and added in choriocarcinoma cells or endometrial stromal cells to compare the cell binding rate of the agents under optical microscope and with flow cytometry.

RESULTSFlow cytometry demonstrated a binding rate of 77.6% between the SonoVue microbubbles and anti-HCG antibody. Light microscopy showed that the total rosette formation rate of the choriocarcinoma cells exposed to the targeted microbubble bearing anti-HCG antibody reached (87.8-/+6.3)%, significantly higher than that of the endometrial stromal cells [(9.4-/+1.7)%, P<0.05]. The binding rate of the targeted microbubbles with the choriocarcinoma cells before and after PBS washing were (85.4-/+4.7)% and (83.1-/+3.8)% (P>0.05), respectively, suggesting strong stability of the binding. The binding rate was 81.0% according to the results of flow cytometry.

CONCLUSIONThe targeted microbubbles as a contrast agent can efficiently bind to the choriocarcinoma cells in vitro with a stability sufficient to resist the blood flow.

Choriocarcinoma ; pathology ; Contrast Media ; metabolism ; Female ; Humans ; Microbubbles ; Phospholipids ; metabolism ; Pregnancy ; Sulfur Hexafluoride ; metabolism ; Uterine Neoplasms ; metabolism

OBJECTIVETo investigate the predominant contribution of methyl-metabolism pathway to the regulation of LuxS of Strecptococcus mutans.

METHODSThe differences in biofilm formation and aciduricity of Strecptococcus mutans among the methyl-metabolism-complementation strain (KO-S), the parental wide-type strain (WT) and the luxS null strain (KO) were observed by real-time PCR for monitoring the transcriptional level of genes related to biofilm formation (smu.238, gtfD) and aciduricity (smu.44, smu.46) of the studied strains, methyl thiazolyl tetrazolium (MTT) for quantifying the biofilm of the exhibited strains and confocal laser scanning microscopy for estimating the structure of the biofilm.

RESULTSThe transcriptional level of smu.44, smu.46, smu.238, gtfD in WT were 1.289 ± 0.051, 1.694 ± 0.140, 1.565 ± 0.107, 1.667 ± 0.196 respectively; in KO were 1.001 ± 0.045, 1.007 ± 0.151, 1.000 ± 0.021, 1.012 ± 0.196 respectively, downregulated compared with WT (P < 0.05); in KO-S were 4.662 ± 0.091, 5.019 ± 0.258, 3.462±0.029, 3.071 ± 0.136 respectively, upregulated compared both with KO and with WT (P < 0.05). The quantity of biofilms formed by the studied strains were WT (1.592 ± 0.213), KO (0.939 ± 0.029), KO- S (2.177 ± 0.226), KO- P (1.020 ± 0.093), respectively, representing a less quantity by KO and KO-P than WT (P < 0.05) and a more quantity by KO-S than other three stains (P < 0.05). According to the observation of biofilms texture by confocal laser scanning microscopy, the WT biofilm was condensed and even. In contrast, fissures and gaps were found scattered in biofilms of KO, KO-P while lessened in that of KO-S, in which high-density bacterial aggregates were observed. The acid assay indicated a smaller biofilm decrease by WT and KO-S than that by KO and KO- P(P < 0.05).

CONCLUSIONSThe methyl- metabolism pathway contributes to LuxS regulation on biofilm formation and auiduricity of Strecptococcus mutans.

Bacterial Proteins ; metabolism ; Biofilms ; Carbon-Sulfur Lyases ; metabolism ; Glucosyltransferases ; Microscopy, Confocal ; Real-Time Polymerase Chain Reaction ; Streptococcus mutans ; metabolism