NOVEL ISOPRENOID MODIFIED PROTEINS IN HALOBACTERIA

Incorporation of [H-3]mevalonic acid-derived materials into proteins w as studied with extremely halophilic archaebacteria, Halobacterium hal obium and Halobacterium cutirubrum. Several labeled proteins were dete cted on SDS-polyacrylamide gel electrophoresis followed by fluorograph y. The majority of the radioactive materials released from the labeled proteins by sulfonium salt cleavage moved with a mobility similar to that of a C-85 polyprenol on reverse-phase thin-layer chromatography, and no radioactive farnesol H as found on the chromatography. However, a weak but significant protein farnesyltransferase activity was detec ted in ill vitro experiments with a combination of [H-3]farnesyl dipho sphate and Ras precursor protein. (C) 1994 Academic Press, Inc.