Cornell University

Thomas Mansell

Matthew DeLisa

Adam Fisher

Cassandra Guarino

The present invention relates to a prokaryotic host cell comprising eukaryotic glycosyltransferase activity, where the eukaryotic glycosyltransferase activity is eukaryotic dolichyl-linked UDP-GlcNAc transferase activity and eukaryotic mannosyltransferase activity. Also disclosed is a method of producing a glycosylated protein by providing a prokaryotic host cell comprising the eukaryotic glycosyltransferase activity and culturing the prokaryotic host cell under conditions effective to produce a glycosylated protein. Another aspect of the present invention pertains to a method for screening bacteria or bacteriophages by expressing one or more glycans on the surface of a bacteria, attaching a label on the one or more glycans on the surface of the bacteria or on the surface of a bacteriophage derived from the bacteria, and analyzing the label in a high-throughput format. A glycosylated antibody comprising an Fv portion which recognizes and binds to a native antigen and an Fc portion which is glycosylated at a conserved asparagine residue is also disclosed.

Glycosylated protein expression in prokaryotes

One aspect of the present invention relates to a reporter system for detection of protein-protein interactions in the periplasm of a prokaryotic host cell. The reporter system includes a first expression system which has a nucleic acid molecule encoding a first fragment of a reporter protein molecule, a nucleic acid molecule encoding a first signal sequence, and a nucleic acid molecule encoding a first member of a putative binding pair, where the nucleic acid molecule encoding the first fragment, the nucleic acid molecule encoding the first signal sequence, and the nucleic acid molecule encoding the first member of the putative binding pair are operatively coupled to permit their expression in a prokaryotic host cell as a first fusion protein. The reporter system also includes a second expression system which has a nucleic acid molecule encoding a second fragment of the reporter protein molecule, a nucleic acid molecule encoding a second signal sequence, and a nucleic acid molecule encoding a second member of the putative binding pair, where the nucleic acid molecule encoding the second fragment, the nucleic acid molecule encoding the second signal sequence, and the nucleic acid molecule encoding the second member of the putative binding pair are operatively coupled to permit their expression in a prokaryotic host cell as a second fusion protein, where, when expressed in a prokaryotic host cell, at least one of the first and the second fusion proteins are co-translationally transported to the periplasm where, when present, the first and second members of the putative binding pair bind together and the first and second fragments of the reporter protein molecule are reconstituted, thereby producing an active reporter protein. The reporter system may be used to carry out methods of identifying candidate compounds which bind to a target protein, identifying a candidate gene which modulates binding between a first protein and second protein, and identifying a candidate compound which modulates binding between a first protein and second protein.

System useful for reporting protein-protein interactions in the bacterial periplasm

The present invention relates to a prokaryotic host cell comprising eukaryotic glycosyltransferase activity, where the eukaryotic glycosyltransferase activity is eukaryotic dolichyl-linked UDP-GlcNAc transferase activity and eukaryotic mannosyl-transferase activity. Also disclosed is a method of producing a glycosylated protein by providing a prokaryotic host cell comprising the eukaryotic glycosyltransferase activity and culturing the prokaryotic host cell under conditions effective to produce a glycosylated protein. Another aspect of the present invention pertains to a method for screening bacteria or bacteriophages by expressing one or more glycans on the surface of a bacteria, attaching a label on the one or more glycans on the surface of the bacteria or on the surface of a bacteriophage derived from the bacteria, and analyzing the label in a high-throughput format. A glycosylated antibody comprising an Fv portion which recognizes and binds to a native antigen and an Fc portion which is glycosylated at a conserved asparagine residue is also disclosed.

The present invention relates to the fields of microbiology, molecular biology and protein biochemistry. More particularly, it relates to compositions and methods for analyzing and altering (e.g., enhancing or inhibiting) protein folding and solubility (e.g., within periplasm). The present invention provides an engineered assay for protein folding and solubility in theperiplasm based on co-translational translocation of a chimera comprising a protein of interest fused to TEM-I &#x3b2;-lactamase that is targeted for export via the signal recognition particle (SRP)-dependent pathway. Using an array of native and heterologous proteins, it is demonstrated that periplasmic folding behavior of proteins is intimately coupled to in vivo &#x3b2;-lactamase activity. As a result of this coupling, the reporter is useful for (1) facile discovery of extrinsic periplasmic factors that affect protein folding and solubility; and (2) genetic selection of solubility-enhanced proteins.

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Ithaca, NY, United States of America

Thomas Mansell