Allen Orville 's research interests explained in more detail:
The toluene 4-monooxygenase (T4MO) multi-protein complex catalyzes the regiospecific hydroxylation of aromatic hydrocarbons. The enzyme complex consists of a two-protein electron transfer chain (an FAD- and [2Fe-2S]-containing NADH oxidoreductase and a Rieske-type [2Fe-2S] ferredoxin), a catalytic effector protein (T4moD) that contains no metal ions or organic cofactors, and a terminal, nonheme diiron-containing hydroxylase. The T4moD binds to the hydroxylase and influences the distribution of products. Our high resolution structures for the natural and several mutant variants of T4moD are the first for this class of protein and support new hypotheses for protein-protein interactions that impact function. We reported crystal structures for native T4moD and two engineered variants with either four (deltaN4) or ten (deltaN10) residues removed from the N-terminal at 2.1-, 1.7- and 1.9-Å resolution, respectively. The crystal structures have C-alpha root mean squared differences of less than 0.8 Å for the central core consisting of residues 11-98, showing that alterations of the N-terminal have little influence on the folded core of the protein. The central core has the same fold topology as observed in the NMR structures of T4moD, the methane monooxygenase effector protein (MmoB) from two methanotrophs, and the phenol hydroxylase effector protein (DmpM). However, the root mean squared differences between comparable C-alpha positions in the X-ray structures and the NMR structures vary from ~1.8 Å to greater than 6 Å, with the higher values likely arising from differences in the numbers of X-ray reflections and NOE restraints used to refine the respective structures.