Isolation and Sequence Analysis of the trpBA Gene Cluster, Encoding Tryptophan Synthase, from Azospirillum brasilense

Abstract

The trpBA ene cluster of Azospirillum brasilense Sp7 was isolated by complementation of an Escherichia coli trpBA mutant. Both genes code for the two subunits of tryptophan synthase, which catalyzes the last step in tryptophan biosynthesis. No structural features indicating transcriptional relation could be identified. Upstream of the trpBA cluster an open reading frame encoding a putative periplasmic binding protein, involve in amino acid transport, was identified. Analysis of the downstream region of the trpBA cluster revealed the presence of a utative open reading frame encodin a subunit of the acetl-coenzyme A carboxylase carboxyl transferase complex.

Key Words:

• Azospirillum
• IAA
• tryptophan synthase
• trpBA
• periplasmic binding protein
• accD