The dapA gene encoding dihydrodipicolinate synthase of Corynebacterium glutamicum is pivotal for high-level L-lysine production. The entire dapB-ORF2-dapA-ORF4 gene cluster was cloned, its sequence of 5907 bp completed, and a Northern analysis was performed. Whereas deletion of ORF2 had no detectable consequences for the cell, the interruption of ORF4 resulted (i) in a decreased growth rate, (ii) an increased specific activity of the diaminopimelate late decarboxylase, and (iii) a decreased specific activity of the diaminopimelate dehydrogenase. Based on these physiological features, and structural features of the ORF4 encoded protein shared with the initiation factor IF2 of Streptococcus faecium, we hypothesize that ORF4 is part of a transcriptional control element in C. glutamicum.