  We discuss the gravity dual description for a non-commutative Yang-Mills
theory, which reduces to that on AdS_{5} x S_{5} in the commutative limit. It
is found that doubletons do not decouple in this dual gravity description
unless one takes the commutative limit. The decoupling of the doubletons in
AdS_{5} space implies that the dual gauge theory has SU(N) gauge symmetry. Our
result implies that this gravity description is dual to non-commutative U(N)
gauge theory. It is compatible with the claim that U(1) and SU(N) gauge
symmetries can not separate in non-commutative U(N) gauge theory.
