Abstract: The present invention relates to isolated and/or recombinant nucleic acids which encode Candida isoleucyl-tRNA synthetases, portions thereof, or fusion proteins comprising a Candida isoleucyl-tRNA synthetase or portion thereof. Also disclosed are constructs comprising the nucleic acids of the present invention, host cells comprising a recombinant nucleic acid or construct, and methods of producing a Candida isoleucyl-tRNA synthetase, portion thereof, or fusion protein comprising same. Also described are tester strains, which are cells engineered to rely on the function of a Candida isoleucyl-tRNA synthetase or functional fragment thereof encoded by an introduced cloned gene, and which can be used in a method of detecting an inhibitor of Candida isoleucyl-tRNA synthetase function.

Abstract: Isolated, recombinant nucleic acids which encode an isoleucyl-tRNA synthetase (IleRS) of human origin have been used to make expression constructs and transformed host cells for the production of a recombinant human IleRS. A recombinant enzyme has been purified, and is active in the specific aminoacylation of tRNA by isoleucine. Isolated, recombinant enzyme, and antibodies made specifically thereto, can be useful in assays to diagnose and monitor the autoimmune disease known as "antisynthetase syndrome." The essential isoleucyl-tRNA synthetases of microbes pathogenic in humans can be the targets of inhibitory agents having antimicrobial activity. A human isoleucyl-tRNA synthetase, isolated and purified, can be used to assess the toxic effect in humans of such an inhibitory agent in various biochemical activity assays. This human enzyme can also be expressed in "tester strains," whose cells rely upon the function of the human isoleucyl-tRNA synthetase for tRNA.sup.Ile charging.