Investigation of a putative RNA helicase in the developmental program of Streptomyces coelicolor

S. coelicolor embodies a unique developmental program. sco3550, which encodes a putative RNA helicase, was originally identified due to its close genomic proximity to the developmental gene, bldG. Western analysis of SCO3550 revealed a doublet corresponding to the predicted molecular weight of native SCO3550. In order to analyze the phenotype of a sco3550 disruption mutant, PCR-targeted REDIRECT(c) mutagenesis was attempted. However, sco3550 appears resistant to complete disruption and putative sco3550 disruption strains revealed a mixture of wild-type and mutant chromosomes. To confirm the biochemical nature of SCO3550 as a RNA helicase, in vitro RNA unwinding assays were performed. The results of the in vitro assays suggest that SCO3550 may act as a specific RNA binding protein to effect dsRNA destabilization in vivo. To examine potential protein-protein interactions with SCO3550, a HIS6-SCO3550 recombinant protein was overexpressed in S. coelicolor and chemical crosslinking studies revealed the presence of a potential high MW complex.