Figure 1. Organization of SAV576 and its adjacent genes on the chromosome of S. avermitilis (A) and schematic representation of the strategy used for deletion of SAV575 and SAV576 genes (B).

(A) Gene notations are based on the Genome Project of S. avermitilis (http://avermitilis.ls.kitasato-u.ac.jp/). The two transcriptional units are indicated by black bars. (B) Long black arrows indicate genes and their directions. Short arrows indicate the positions of primers used for cloning exchange regions and confirming gene deletions. White blocks represent in-frame deletions in the corresponding genes.