The present disclosure relates to a modified polypeptide of glutamine synthetase having enhanced activity and a method of producing L-glutamine using the same. Since production of L-glutamine may be increased by using the novel modified polypeptide without a decrease in a growth rate compared to wild-type strains having glutamine synthetase activity, the modified polypeptide may be widely used for mass production of L-glutamine.

Ligase mutants of the following (1), (2), or (3): (1) a ligase mutant comprising an amino acid sequence showing 95% or more identity to the amino acid sequence of SEQ ID NO: 1, and having a nucleic acid-linking activity; (2) a ligase mutant comprising an amino acid sequence showing 90% or more identity to the amino acid sequence of SEQ ID NO: 2, and having a nucleic acid-linking activity; or (3) a ligase mutant comprising an amino acid sequence showing 97% or more identity to the amino acid sequence of SEQ ID NO: 3, and having a nucleic acid-linking activity, have excellent properties.

Provided herein are methods, compositions, and non-naturally occurring microbial organism for preparing compounds such as α-butanol, butyric acid, succinic acid, 1,4-butanediol, 1-pentanol, pentanoic acid, glutaric acid, 1,5-pentanediol, 1-hexanol, hexanoic acid, adipic acid, 1,6-hexanediol, 6-hydroxy hexanoic acid, ε-Caprolactone, 6-amino-hexanoic acid, ε-Caprolactam, hexamethylenediamine, linear fatty acids and linear fatty alcohols that are between 7-25 carbons long, linear alkanes and linear α-alkenes that are between 6-24 carbons long, sebacic acid and dodecanedioic acid comprising: a) converting a C.sub.N aldehyde and pyruvate to a C.sub.N+3 β-hydroxyketone intermediate through an aldol addition; and b) converting the C.sub.N+3 β-hydroxyketone intermediate to the compounds through enzymatic steps, or a combination of enzymatic and chemical steps.

The present disclosure belongs to the field of bioengineering, and relates to breeding of industrial microorganisms, in particular to a genetically engineered strain of Saccharomyces cerevisiae, method for constructing the same, and its use for brewing, the genetically engineered strain of Saccharomyces cerevisiae heterogeneously overexpresses an acetaldehyde dehydrogenase gene ALD6, an acetyl-CoA synthase gene ACS1 and an alcohol acyltransferase gene AeAT9. The Saccharomyces cerevisiae strain with high yield of ethyl acetate and low yield of higher alcohols provided by the present disclosure not only maintains excellent ethanol fermentation characteristics, but also reducing the production of higher alcohols which adversely affect the comfort after drinking, which is of great significance for a well-maintained and strengthened flavor characteristics of Chinese Baijiu, an improved and stabilized quality thereof, and even a reform in the fermentation process thereof.

Provided herein are systems and methods for the production of malonic acid or a salt thereof in recombinant host cells.

Provided herein is a polymerase-free enzyme mix (FRAG) for fragmenting double-stranded DNA. In some embodiments the enzyme mix may comprise a double-stranded DNA nickase and at least one of a DNA ligase capable of sealing a nick within a DNA, and a single-strand specific DNA nuclease. Methods for fragmenting double-stranded DNA are also provided.

The present invention relates to a mutated virus. Said virus can be an influenza virus of human or other animal origin. The present invention also relates to a method for preparing the mutated virus, the method comprising introducing UAG codons into positions upstream of the stop codons per se of one or more genes of a viral genome by reverse genetic techniques. The present invention further relates to uses of the mutated virus, for example, as a live attenuated vaccine, or in replication of controllable and safe virus models, and the like.

Provided are a method for large-scale synthesis of a long-chain RNA and a method for site-specific modification of the long-chain RNA. The method for large-scale synthesis of a long-chain RNA comprises: designing short RNA fragments and splint DNA fragments; ligating; capping; and removing the splint DNA fragments and other steps. A large number of short RNA fragments and different splint DNA fragments are chemically synthesized, and then the different short RNA fragments are ligated by a biological method so as to form a target long-chain RNA. The product long-chain RNA has a low mutation rate, a plurality of the short RNA fragments can be assembled in a single reaction, and the long-chain RNA can be synthesized at a high throughput so as to fulfill the large-scale production of the long-chain RNA. In addition, by chemical modification of the short RNA fragments, the site-specific modification of the long-chain RNA can be realized.

The present invention involves the ability to 1) use a virus assisted directed evolution platform to significantly improve the activity of engineered nonsense-suppressor tRNAs in mammalian cells, 2) provide mutants of archaeal pyrrolysyl and E. coli leucyl tRNAs that show remarkably improved Uaa incorporation efficiency in mammalian cells, and 3) use these tRNAs to express recombinant proteins in mammalian cells incorporating Uaas at significantly improved yields.

Provided herein are, inter alia, methods of forming chemically reactive amino acids and methods of using same.