Isolation and characterization of promoter regions from Streptococcus gordonii CH1

Abstract

We aimed to identify transcription signal sequences from Streptococcus gordonii strain CH1 by random chromosomal cloning. Five genomic fragments from a Sau3A digest, which constitutively activated transcription of a promoterless spectinomycin resistance gene in this strain, were isolated and characterized. Additionally, one promoter fragment was isolated that was specifically activated under iron-limiting conditions. A sequence motif with similarity to the consensus for Fur-binding regulatory DNA sequences (Fur box) in Escherichia coli was detected within the putative promoter region. The open reading frame downstream of this region possibly encodes a transmembrane protein involved in iron uptake.