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Nanozymes, a kind of nanomaterial with enzyme-like activity, overcomes many shortcomings of natural enzymes and gradually shines in the field of stomatology.

SummaryThe world's major crops are deficient in lysine and several other amino acids essential for human and animal nutrition. Increasing the content of these amino acids in cereals, our major source of dietary energy, can help feed a global population whose reliance upon dietary protein is growing faster than crop yields. Here we document the heritable expression in rice, the world's major cereal crop, of tRNA lys species that introduce lysine at alternative codons during protein synthesis, resulting in a significant enrichment of the lysine content of proteins in rice seeds without changing the types or quantities of the seed storage proteins.

Dbf4 is the regulatory subunit of Cdc7 kinase, which is essential for entry into and traversing through S phase. The level of Dbf4, which is critical for the activation of Cdc7, is regulated by transcription and protein degradation. To gain a better understanding as to how the transcription of human Dbf4 (HuDbf4) is regulated, we have cloned and characterized its promoter. We found that HuDbf4 core promoter is localized within 7 211 to 7285 of the translation start-codon. This 75 bp DNA segment contains, among others, a putative MluI Cellcycle Box (MCB). A point mutation within the MCB dramatically reduced the promoter activity. This is the first example that an MCB element plays an essential role in the activation of a core promoter in mammalian cells. The auxiliary elements required for the full promoter activity are present within 162-bp upstream from the core promoter (i.e., 7286/7447). A point mutation within the Sp1 element at 7353/7361 resulted in a decrease of promoter activity to the basal level, while the deletion of the putative HES-1 at 7326/7331 dramatically increased the promoter activity. Taken together, our data suggests that the MCB element is essential for the core promoter activation, while the Sp1 positive regulator and the HES-1 repressor coordinately determine the efficiency of the HuDbf4 promoter. We have also found: (i) that the major transcription initiations occur at 7220, 7235 and 7245; (ii) that HuDbf4 gene consists of 12 exons, which spread over a 33-kb region.

SummaryThe Arabidopsis thaliana lysyl tRNA synthetase (AtKRS) structurally and functionally resembles the wellcharacterized prokaryotic class IIb KRS, including the propensity to aminoacylate tRNA Lys with suboptimal identity elements, as well as non-cognate tRNAs. Transient expression of AtKRS in carrot cells promotes aminoacylation of such tRNAs in vivo and translational recoding of lysine at nonsense codons. Stable expression of AtKRS in Zea mays causes translational recoding of lysine into zeins, significantly enriching the lysine content of grain.

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