1 promoter in AZD8931 purchase M. gallisepticum S6 [16]. A major drawback of the use of ß-galactosidase (ß-Gal) as a reporter is its limited ability to pass through the bacterial cytoplasmic membrane [17]. When the gene for an exported protein is fused to lacZ , the hybrid protein is membrane bound and such proteins have very low ß-galactosidase activity [18]. Green fluorescent protein (GFP) has been used to identify promoter sequences in DNA libraries of

Mycoplasma pneumoniae and Mycoplasma genitalium in E. coli [19], but GFP could not be detected following transformation in M. gallisepticum [20]. The chloramphenicol acetyl transferase (CAT) gene has also been used as a selectable marker in M. pneumoniae using a modified Tn4001 transposon [21]. The phoA gene selleck screening library codes for the E. coli periplasmic alkaline phosphatase (AP), and is active when exported across the cytoplasmic membrane

into the periplasmic space [22–24]. Functional alkaline phosphatase is a dimer of two identical subunits and each subunit contains two intramolecular disulfide bridges. The amino-terminal signal sequence is cleaved upon translocation across the cytoplasmic membrane, and the mature PhoA is folded into an active conformation after export to the periplasmic space. Disulfide bond formation is followed by folding into monomers and then conversion to the active dimer conformation [25]. Enzymatic activity of PhoA fusion proteins depends on the presence of an export sequence and this principle has been used in developing reporter vectors to determine membrane PDK4 protein topology and to facilitate identification of genes involved in bacterial virulence [26]. The aim of this study was to evaluate whether the E. coli phoA gene was suitable for use as a reporter gene to investigate gene expression and protein processing in mycoplasmas, using a construct incorporating signal sequences from the M. gallisepticum VlhA1.1 this website lipoprotein and the ltuf promoter to express PhoA as a membrane-associated

lipoprotein. Results Construction of plasmid ltuf acy phoA (pTAP) The elongation factor Tu promoter region of 277 bp (ltuf) (GenBank accession: X16462) and the leader sequence of the vlh A1.1 gene (GenBank accession: U90714) from M. gallisepticum were originally amplified by PCR from the genomic DNA of M. gallisepticum strain S6 and ligated into the pISM2062.2lac[14] vector to produce the ltuf sig lac construct [20]. The ltuf promoter region was amplified from M. gallisepticum genomic DNA by PCR using the LNF and TSR oligonucleotide primers (Table 1), and the vlh A export signal sequence of 51 bp was amplified from M. gallisepticum genomic DNA using the TSF and LBR primers (Table 1). These two products were then joined by overlap extension PCR using the primers LNF and LBR. The resultant PCR product was ligated into pGEM-T (Promega) following the manufacturer’s instructions.