Nucleotide sequence of the Escherichia coli solA gene encoding a sarcosine oxidase-like protein and characterization of its product.

An Escherichia coli gene, designated solA, was identified between pyrC and htrB around 24.2 min of the genetic map. The solA gene product (SolA, 372 aa) shows strong similarities (at most 42% identities over the entire length) to monomeric sarcosine (N-methylglycine) oxidases from other bacteria. However, only low levels of sarcosine oxidase activity were detected, even when SolA was overproduced. The SolA extracts exhibited much higher (about 200-fold) reactivity toward N-methyltryptophan than toward sarcosine. Thus, SolA appears to have a substrate specificity distinct from that of monomeric sarcosine oxidases, in spite of the strong similarities in the primary structure with such enzymes.