Humans ; Phosphorylation ; Serine ; Protein Serine-Threonine Kinases/metabolism* ; Spasms, Infantile

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*

Humans ; Phosphorylation ; Serine/metabolism* ; Protein Serine-Threonine Kinases/metabolism* ; Signal Transduction ; Neovascularization, Pathologic

In order to investigate the molecular mechanism of silk/threonine protein kinase (STK)-mediated blue light response in the algal Chlamydomonas reinhardtii, phenotype identification and transcriptome analysis were conducted for C. reinhardtii STK mutant strain crstk11 (with an AphvIII box reverse insertion in stk11 gene coding region) under blue light stress. Phenotypic examination showed that under normal light (white light), there was a slight difference in growth and pigment contents between the wild-type strain CC5325 and the mutant strain crstk11. Blue light inhibited the growth and chlorophyll synthesis in crstk11 cells, but significantly promoted the accumulation of carotenoids in crstk11. Transcriptome analysis showed that 860 differential expression genes (DEG) (559 up-regulated and 301 down-regulated) were detected in mutant (STK4) vs. wild type (WT4) upon treatment under high intensity blue light for 4 days. After being treated under high intensity blue light for 8 days, a total of 1 088 DEGs (468 upregulated and 620 downregulated) were obtained in STK8 vs. WT8. KEGG enrichment analysis revealed that compared to CC5325, the crstk11 blue light responsive genes were mainly involved in catalytic activity of intracellular photosynthesis, carbon metabolism, and pigment synthesis. Among them, upregulated genes included psaA, psaB, and psaC, psbA, psbB, psbC, psbD, psbH, and L, petA, petB, and petD, as well as genes encoding ATP synthase α, β and c subunits. Downregulated genes included petF and petJ. The present study uncovered that the protein kinase CrSTK11 of C. reinhardtii may participate in the blue light response of algal cells by mediating photosynthesis as well as pigment and carbon metabolism, providing new knowledge for in-depth analysis of the mechanism of light stress resistance in the algae.
Chlamydomonas reinhardtii/genetics* ; Photosynthesis/genetics* ; Plants/metabolism* ; Protein Kinases ; Threonine/metabolism* ; Carbon/metabolism* ; Serine/metabolism*

Leader peptidase is a novel serine protease in Escherichia coli, which catalyzes the cleavage of amino-terminal signal sequences from exported proteins. It is an integral membrane protein containing two transmembrane segments with its carboxy-terminal catalytic domain residing in the periplasmic space. Recently, the x-ray crystal structure of signal peptidase-inhibitor complex showed that Asp 280, a highly conserved consensus sequence of E. coli leader peptidase is the closest charged residue in the vicinity of two catalytic dyad, Ser 90 and Lys 145, and it is likely held in place by a salt bridge to Arg 282. Possible roles of Asp 280 and Arg 282 in the structure-catalytic function relationship were investigated by the site-directed mutagenesis of Asp 280 substituted with alanine, glutamic acid, glycine, or asparagine and of Arg 282 with methionine. All of mutants purified with nickel affinity chromatography were inactive using in vitro assay. It is surprising to find complete lose of activity by an extension of one carbon units in the mutant where Asp 280 is substituted with glutamic acid. These results suggest that Asp 280 and Arg 282 are in a sequence which constitutes catalytic crevice of leader peptidase and are essential for maintaining the conformation of catalytic pocket.
Aspartic Acid/chemistry* ; Bacterial Outer Membrane Proteins/metabolism ; Blotting, Western ; Escherichia coli/enzymology* ; Escherichia coli/chemistry ; Micrococcal Nuclease/metabolism ; Mutagenesis, Site-Directed ; Oligonucleotides ; Protein Precursors/metabolism ; Serine Endopeptidases/metabolism* ; Serine Endopeptidases/genetics ; Serine Endopeptidases/chemistry* ; Structure-Activity Relationship

OBJECTIVETo investigate the time course of changes in the expression of fibroblast activation protein (FAP) during healing of skin scald burns in rats.

METHODSAdult Wistar rats were randomized into two equal groups (n=42) and subject to superficial second degree and deep second degree scald burns on the dorsal skin groups, with 6 normal rats serving as the control group. At 6 h, 12 h, and 1, 3, 7, 14, and 21 days after burns, 6 rats from each group were sacrificed to detect FAP expression by immunohistochemistry and Western blotting.

RESULTSFAP was expressed on the cell membrane and in the cytoplasm of the fibroblasts, especially those around the neovessels. In both burn groups, FAP expression increased significantly at 6 h after burns. In superficial burn group, FAP expression was comparable between 6 and 12 h and between 1 and 3 days (P>0.05), but showed significant differences between the other time points (P<0.05). In deep burn group, FAP expression was comparable between 12 h, 1 day and 3 days (P>0.05) but differed significantly between the other time points (P<0.05). In both burn groups, FAP expression reached the peak level at 7 days followed by a gradual declination. At 21 days after the burns, FAP maintained a significantly higher expression level than the control level (P<0.05).

CONCLUSIONThe time course of the changes of FAP expression following scald burns suggests an important role of FAP in the healing process of scald burns.

Animals ; Burns ; metabolism ; rehabilitation ; Face ; Gelatinases ; metabolism ; Membrane Proteins ; metabolism ; Rats ; Rats, Wistar ; Serine Endopeptidases ; metabolism ; Skin ; metabolism ; Wound Healing

Epilepsy ; drug therapy ; metabolism ; Humans ; Signal Transduction ; TOR Serine-Threonine Kinases ; antagonists & inhibitors ; metabolism

Mechanistic target of rapamycin (mTOR) signaling governs important physiological and pathological processes key to cellular life. Loss of mTOR negative regulators and subsequent over-activation of mTOR signaling are major causes underlying epileptic encephalopathy. Our previous studies showed that UBTOR/KIAA1024/MINAR1 acts as a negative regulator of mTOR signaling, but whether UBTOR plays a role in neurological diseases remains largely unknown. We therefore examined a zebrafish model and found that ubtor disruption caused increased spontaneous embryonic movement and neuronal activity in spinal interneurons, as well as the expected hyperactivation of mTOR signaling in early zebrafish embryos. In addition, mutant ubtor larvae showed increased sensitivity to the convulsant pentylenetetrazol, and both the motor activity and the neuronal activity were up-regulated. These phenotypic abnormalities in zebrafish embryos and larvae were rescued by treatment with the mTORC1 inhibitor rapamycin. Taken together, our findings show that ubtor regulates motor hyperactivity and epilepsy-like behaviors by elevating neuronal activity and activating mTOR signaling.
Animals ; Hyperkinesis/genetics* ; Mutation/genetics* ; Signal Transduction ; TOR Serine-Threonine Kinases/metabolism* ; Zebrafish/metabolism*

Humans ; Osteosarcoma ; metabolism ; Signal Transduction ; physiology ; TOR Serine-Threonine Kinases ; metabolism

Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase, which plays an essential role in cell growth, proliferation and survival. mTOR regulates the transcription of mRNA, synthesis of ribosome and gene expression for metabolism. By forming mTOR complex, it regulates cellular activities by phosphorylating its downstream proteins, such as S6 protein kinase and 4E-BP1. In recent years, the role of mTORC1 in regulating aging is gradually recognized. Studies of physiological function and the regulatory mechanisms of mTOR signaling can not only help to better understand the aging mechanism for cells or organs, but also provide insights as to finding potential new drug targets for aging related diseases. This review focuses on recent advances of mTOR and aging related diseases in hematopoietic and other organ systems.
Aging ; Hematopoietic System ; metabolism ; Humans ; Signal Transduction ; TOR Serine-Threonine Kinases ; metabolism