Inducible expression of choline sulfatase and its regulator BetR in Pseudomonas sp. ATCC19151

Abstract

Pseudomonas sp. strain ATCC19151 is a natural isolate from sewage with the ability to degrade detergents. Genes encoding potential choline sulfatase (betC), substrate-binding ABC transporter protein (betD), sulfate transporter (betE), and divergent putative transcriptional regulator (betR) were cloned and characterized from strain ATCC19151. In silico analysis revealed that (1) the BetC protein belongs to alkPPc superfamily and shares CXPXR sequence with the cysteine sulfatases of group I, (2) BetR belongs to the LysR family of transcriptional regulators, (3) BetD is part of the PBPb superfamily of periplasmic and membrane-associated proteins, and (4) BetE is a permease and contains STAS domain. Insertional mutagenesis and genetic complementation show that betC gene encodes a functional choline sulfatase. Analysis of the betC (P(betC)) and betR (P(betR)) promoters revealed that they are inducible. BetR activates betC and betR transcription in the presence of choline sulfate, whilst in the absence of choline sulfate, BetR represses its own transcription. It was further established that BetR directly binds to betC-betR intergenic region in vitro, with higher affinity in the presence of choline sulfate as cofactor. Transcription of betC and betR was not induced in the presence of high concentration of NaCl.