New England Biolabs, Inc.

Eric E Adam

Francine B Perler

Ming-Qun Xu

Donald G Comb

Christopher J Noren

William E Jack

Maurice W Southworth

Robert A Hodges

Shaorong S Chong

In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize theGyrA intein orDnaB helicase intein are provided. Similar reporter systems utilizing native or homologous exteins and systems utilizing controllable inteins are provided, as are methods of controlling in vivo expression of proteins by modulating protein splicing with inhibiting or activating agents, and methods of controlling the delivery of proteinaceous drugs in vivo by modulating protein splicing.

Screening and use of agents which block or activate intein splicing utilizing natural or homologous exteins

In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize the GyrA intein or DnaB helicase intein are provided. Similar reporter systems utilizing native or homologous exteins and systems utilizing controllable inteins are provided, as are methods of controlling in vivo expression of proteins by modulating protein splicing with inhibiting or activating agents, and methods of controlling the delivery of proteinaceous drugs in vivo by modulating protein splicing.

Screening and use of reagents which block or activate intein splicing utilizing natural or homologous exteins

The present invention is directed to modified proteins and methods of their production. The modified proteins comprise a controllable intervening protein sequence (CIVPS) inserted into or adjacent a target protein, the CIVPS being capable of excision from or cleavage of the modified protein under predetermined conditions in cis or in trans, i.e., increase in temperature, exposure to light, unblocking of amino acid residues by dephosphorylation, treatment with chemical reagents or deglycosylation. If desired, the modified protein can be subjected to these conditions. The CIVPS may also be inserted into a region that substantially inactivates target protein activity. The CIVPS may be used in a number of applications including purification of the target protein in a one-step protocol.

Modified proteins comprising controllable intervening protein sequences

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Beverly, MA, United States of America

Eric E Adam