Structural constraints and emergence of sequence patterns in protein evolution

The aim of this work was to study the relationship between structure conser vation and sequence divergence in protein evolution. To this end, we develo ped a model of structurally constrained protein evolution (SCPE) in which t rial sequences, generated by random mutations at gene level, are selected a gainst departure from a reference three-dimensional structure. Since at the mutational level SCPE is completely unbiased, any emergent sequence patter n will be due exclusively to structural constraints. In this first report, it is shown that SCPE correctly predicts the characteristic hexapeptide mot if of the left-handed parallel beta helix (L betaH) domain of UDP-N-acetylg lucosamine acyltransferases (LpxA).