Members of the SWI2/SNF2 family of proteins participate in an array of nucleic acid metabolic functions, including chromatin remodeling and transcription. The present studies identify a novel strategy to specifically inhibit the functional DNA-dependent adenosinetriphosphatase (ATPase) motor domain common to SWI2/SNF2 family members. We have identified preparations of phosphoaminoglycosides, which are natural products of aminoglycoside-resistant bacteria, as inhibitors of the in vitro activities of three SWI2/SNF2 family members. These compounds inhibit the ATPase activity of the active DNA-dependent ATPase A domain (ADAAD) by competing with respect to DNA and thus have no effect on DNA-independent ATPases or on RNA-dependent ATPases. Within the superfamily of DNA-dependent ATPases, these compounds are most potent toward SWI2/SNF2 family members and less potent toward other DNA-dependent ATPases. We demonstrate that it is feasible to target DNA-dependent ATPases of a particular type without affecting the function of other ATPases. As the SWI2/SNF2 proteins have been proposed to function in all aspects of DNA metabolism, this paper provides an archetype for development of DNA metabolic inhibitors.