Chondroitin sulfate (CS) is widely applied in the medical, clinical, and nutraceutical fields. However, all commercialized CS is extracted from animal tissues, which is associated with many problems, such as...

3′-Phosphoadenosine-5′-phosphosulfate (PAPS) is a universal sulfate group donor for all biological sulfation reactions in living organisms. Ambitions to biomanufacture sulfate-containing compounds such as heparin and chondroitin sulfate also promote the study on PAPS in vitro synthesis. However, the established enzymatic synthesis of PAPS faces hurdles of the natural low theoretical transformation rate of 50% (two ATP to one PAPS) and high cost. Here, we developed a PAPS synthesis route with 100% theoretical transformation rate which affords equimolar transformation of ATP to PAPS. By fusing the identified adenosine 5′-triphosphate sulfurylase and adenosine 5′-phosphosulfate kinase from different species, we created an artificial active bifunctional enzyme to directly convert ATP to PAPS. To maximize the conversion from ATP to PAPS, a polyphosphate (polyP)-dependent ATP regeneration system was designed and engineered by screening polyP kinases which consumes the low-cost polyP as the phosphate donor. In addition, we found that PPi could be used as the phosphate donor for phosphorylating ADP to ATP by polyP kinases. After demonstration of the wide distribution of PPi kinase activity in polyP kinases, a closed-loop ATP regeneration route was thereupon created to convert one ATP to one PAPS in theory. Using PPi as the phosphate donor, the conversion rate of ATP to PAPS reached 92.3%. The efficient enzymatic route that is constructed here for PAPS synthesis with low cost would boost the biosynthesis of sulfated compounds and peptides.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a high mortality rate and poor prognosis. However, little is known concerning the molecular mechanism of PDAC at the proteomics level. Here we report a proteomics analysis of PDAC tumor and adjacent tissues by shotgun proteomics followed by label-free quantification, and in total, 3031 and 3306 proteins were identified in three pairs of PDAC tumor and adjacent tissues, respectively; 40 of them were differentially expressed for at least three-fold in PDAC tumor tissues. Ontological and interaction network analysis highlighted the dysregulation of a set of four proteins in the carboxypeptidase family: carboxypeptidase A1 (CPA1), A2 (CPA2), B1 (CPB1), and chymotrypsin C (CTRC). Western blotting confirmed the downregulation of the carboxypeptidase network in PDAC. Immunohistochemistry of tissue microarray from 90 PDAC patients demonstrated that CPB1 was downregulated 7.07-fold (P < .0001, n = 81) in tumor comparing with the peritumor tissue. Further 208 pancreatic tissues from PDAC tumor, peritumor, and pancreatis confirmed the downregulation of CPB1 in the PDAC patients. In summary, our results displayed that the expression of carboxypeptidase is significantly downregulated in PDAC tumor tissues and may be novel biomarker in the patient with PDAC.

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Many genetic tools for gene regulation have been developed during the past decades. Some of them edit genomic DNA, such as nucleotides deletions and insertions, while the others interfere with the gene transcriptions or messenger RNA translation. Here, we report a posttranscriptional regulation tool which is termed "Modulation via the small RNA (sRNA)-dependent operation system: MS-DOS" by engineering the type I toxin-antitoxin system in Bacillus subtilis. MS-DOS depends simply on insertion of an operation region (OPR; partial toxin-encoding region) downstream of a genomic open reading frame of interest and overexpression of the coupling antitoxin sRNA from a plasmid. Pairing between the OPR and the sRNA will trigger the RNAse degradation of the transcripts of selected genes. MS-DOS allows for the quantitative, specific, and reversible knockdown of single or multiple genomic genes in B. subtilis. We also showed that the truncated antitoxin SR4 with 53 nt length is sufficient to repress gene expression. Superior to other existing RNA based interfering systems, MS-DOS allows simultaneous knockdown of multiple genes with effortless expression of a single antitoxin RNA. This sRNA-guided repression system will further enrich the gene regulation tools and expand the gene regulation flexibility.