Streptomyces ansochromogenes SanG is a pathway-specific regulator that mainly controls the transcription of two transcriptional units involved in nikkomycin biosynthesis [1].SanG consists of three major functional domains:an N-terminal SARP domain,a central ATPase domain,and a C-terminal half homologous to guanylate cyclases belonging to LuxR family.SanG was expressed in Escherichia coli as a C-terminal His6-tagged protein.An electrophoretic mobility-shift assay (EMSA)showed that the purified SanG protein could bind to the DNA fragment containing the bidirectional sanN-sanO promoter region.