Structural similarities in the noncatalytic domains of phenylalanyl‐tRNA and biotin synthetases

Abstract

Detailed comparison between the structures of the Escherichia coli biotin synthetase/repressor protein (BirA) and the recently solved Thermus thermophilus phenylalanyl‐tRNA synthetase (PheRS) reveals significant similarities outside their respective catalytic domains. These comprise a DNA‐binding α+β domain and an Src‐homology 3 (SH3)‐like domain that were observed in both enzymes. This similarity provides a novel example in which all domains of one multidomain protein appear to be constituents of the other multidomain protein and supports a concept of a common ancestor for two different synthetase families. Copyright © 1995 The Protein Society