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Changing the net charge from negative to positive makes ribonuclease Sa cytotoxic
Author(s) -
Ilinskaya Olga N.,
Dreyer Florian,
Mitkevich Vladimir A.,
Shaw Kevin L.,
Pace C. Nick,
Makarov Alexander A.
Publication year - 2002
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.0216702
Subject(s) - ribonuclease , cytotoxic t cell , cytotoxicity , mutant , rnase p , microbiology and biotechnology , chemistry , streptomyces aureofaciens , biology , biochemistry , gene , rna , genetics , in vitro , streptomyces , bacteria
Ribonuclease Sa (pI = 3.5) from Streptomyces aureofaciens and its 3K (D1K, D17K, E41K) (pI = 6.4) and 5K (3K + D25K, E74K) (pI = 10.2) mutants were tested for cytotoxicity. The 5K mutant was cytotoxic to normal and v‐ ras ‐transformed NIH3T3 mouse fibroblasts, but RNase Sa and 3K were not. The structure, stability, and activity of the three proteins are comparable, but the net charge at pH 7 increases from −7 for RNase Sa to −1 for 3K and to +3 for 5K. These results suggest that a net positive charge is a key determinant of ribonuclease cytotoxicity. The cytotoxic 5K mutant preferentially attacks v‐ ras ‐NIH3T3 fibroblasts, suggesting that mammalian cells expressing the ras‐ oncogene are potential targets for ribonuclease‐based drugs.