Structural model of the R state of Escherichia coli aspartate transcarbamoylase with substrates bound.

ABSTRACT: The allosteric enzyme aspartate transcarbamoylase (ATCase) exists in two conformational states. The enzyme, in the absence of substrates is primarily in the low-activity T state, is converted to the high-activity R state upon substrate binding, and remains in the R state until substrates are exhausted. These conformational changes have made it difficult to obtain structural data on R-state active-site complexes. Here we report the R-state structure of ATCase with the substrate Asp and the substrate analog phosphonoactamide (PAM) bound. This R-state structure represents the stage in the catalytic mechanism immediately before the formation of the covalent bond between the nitrogen of the amino group of Asp and the carbonyl carbon of carbamoyl phosphate. The binding mode of the PAM is similar

SUBMITTER: Wang J 

PROVIDER: S-EPMC2720131 | biostudies-literature | 2007 Aug

REPOSITORIES: biostudies-literature