TABLE 3.

Phosphatase activities of R. capsulatus wild type and F14 [Δ(orf2-sqr)] expressing protein fusions of SQR with PhoA^a

Strain with plasmid and protein fusion	PhoA activity (OD420)
	Without sulfide	With sulfide
Wild type
None	0.04	0.03
pPSAPo and SQR::PhoA	0.04	0.72
pPSAP108 and SQR108::PhoA	0.05	0.05
pPSAP389 and SQR389::PhoA	0.04	0.05
F14
None	0.04	0.07
pPSAPo and SQR::PhoA	0.05	0.70
pPSAP108 and SQR108::PhoA	0.03	0.06
pPSAP389 and SQR389::PhoA	0.03	0.04

^aThe fusion SQR::PhoA consists of the full-length SQR (427 amino acid residues) fused to PhoA. In SQR108::PhoA and in SQR389::PhoA, the N-terminal 108 and 389 amino acid residues, respectively, are fused with PhoA. Samples were taken from heterotrophically grown cultures without sulfide and cultures after incubation with 0.3 mM sulfide for 10 h. PhoA activity is given as the difference between the OD₄₂₀ of the samples and that of the control as described in Materials and Methods.