S. gordonii gene clusters up-regulated in response to CSP at 15 min and preceded by a putative combox regulatory site (). Putative proteins encoded by each gene are shown. (A) Late gene consensus sequences. Genetic loci and proteins encoded by the first up-regulated ORF downstream of the combox sequence are listed. Comparison to the consensus combox sequence and the distances to the putative start codon of the ORF immediately downstream of the consensus sequence are shown. In the case of the combox upstream of the bacteriocin SthA, the distance to SGO_0117, encoding a hypothetical protein (HP) that was not expressed in any of the experiments, as well as the distance to SGO_0116, encoding the SthA bacteriocin, are both shown. S. pneumoniae homologs in strains TIGR4 (gene loci SP) and R6 (gene loci SPR) for the S. gordonii loci are shown. All S. pneumoniae homologs except SPR2021 are preceded by a similar combox sequence () and have been shown to be up-regulated in response to CSP in both strains R6 and Rx (, ). SGO_2094 does not have a significant homolog in S. pneumoniae strain TIGR4, whereas strain R6 does carry a GSP781 homolog (SPR2021); the gene encoding this protein has not been implicated in the S. pneumoniae competence response (). (B) S. gordonii gene clusters with identified comboxes. Clusters of genes up-regulated at 15 min after CSP exposure and positioned downstream of the combox consensus sequence (C) are shown. Gene loci are designated by the SGO number above each arrow; putative encoded proteins are shown within the arrows. Directions of the arrows indicate the 5′→3′ direction of each ORF in relation to the chromosomal origin of replication. Arrow sizes are not to scale. Arrows with dashed lines do not represent 15-min CSP-responsive ORFs and either were classified as representing early-response competence genes (encoding ComA, ComB, and ComX) or were not expressed in the microarray under any of the conditions tested (HP encoded by SGO_0117).