Gene clusters under the control of MtaR. (A) Genes differentially expressed in the mtaR mutant that cluster in four regions of the GBS COH1 chromosome. The filled, colored arrows represent genes differentially expressed in the mtaR mutant. The color of the arrow corresponds to the functional category predicted or established for the each gene: light green, transport and binding; light pink, protein fate; dark green, energy metabolism; grey, hypothetical, and dark pink, amino acid biosynthesis. Open arrows represent genes not differentially expressed in the mtaR mutant. The arrows above the gene clusters represent primers used for transcriptional linkage experiments depicted in panel B. (B) RT-PCR was performed using RNA harvested from GBS strain COH1. PCR reactions were performed with or without RT enzyme or chromosomal DNA. The number of the cluster analyzed in each experiment is indicated above the corresponding gel. The designation and location of the primers utilized are indicated in panel A and the primer sequences are listed in the text.