Subunit Interactions within the @entity505 - XXXX Lyase Complex from @entity526 .

@entity14872 @entity3884 @entity4613 @entity7294 @entity8108 @entity6189 @entity505 @entity3151 @entity5139 @entity526 @entity60417
Phosphonates are a large class of @entity5139 compounds with a characteristic @entity505 - @entity3151 bond. The genes responsible for @entity14872 utilization in Gram-negative bacteria are arranged in an operon of 14 genes. The @entity505 - @entity3151 lyase complex, encoded by the genes phnGHIJKLM, catalyzes the cleavage of the stable @entity505 - @entity3151 bond of @entity60417 to the corresponding @entity7294 and inorganic @entity4613 . Recently, complexes of this enzyme containing five subunits (PhnG- @entity8108 -I-J-K), four subunits (PhnG- @entity8108 -I-J), and two subunits (PhnG-I) were purified after expression in @entity526 ( Proc. Natl. Acad. Sci., U. S. A. 2011 , 108 , 11393 ). Here we demonstrated using mass spectrometry, ultracentrifugation, and chemical cross-linking experiments that these complexes are formed from a PhnG2I2 core that is further elaborated by the addition of two copies each of PhnH and PhnJ to generate PhnG2H2I2J2. This complex adds an additional subunit of PhnK to form PhnG2H2I2J2K. Chemical cross-linking of the five-component complex demonstrated that PhnJ physically interacts with both PhnG and PhnI. We were unable to demonstrate the interaction of PhnH or PhnK with any other subunits by chemical cross-linking. @entity3884 - @entity6189 exchange was utilized to probe for alterations in the dynamic properties of individual subunits within the various complexes. Significant regions of PhnG become less accessible to @entity3884 / @entity6189 exchange from solvent within the PhnG2I2 complex compared with PhnG alone. Specific regions of PhnI exhibited significant differences in the @entity8108 /D exchange rates in PhnG2I2 and PhnG2H2I2J2K.
