S. marcescens KCTC 2172로부터 유전자 은행을 작성하여 재조합 클론 pDH3를 얻었으며, pDH3 유래의 서브클론을 작성하였다. 플라스미드 pPH4의 전염기서열 5,137 bp 영역을 결정한 결과 3개의 ORF가 있음을 확인하였다. 이들은 pst 오페론의 pstC, pstA, 및 pstB, 세 유전자를 동일 전사방향으로 코드하고 있었다. 타 세균의 유전자와 비교한 결과 S. marcescens의 pst 오페론은 pstS와 phoU가 결손되어 있다. 조절영역에는 CRP 결합영역과 pho box 서열이 존재하였다. 보고된 유전자와 상동성 조사결과, PstC 단백질은 Yersinia sp., Vibrio sp. 및 Pseudomonas sp.와는 49, 37, 33%의 상동성을, PstA 단백질은 Yersinia sp., Vibrio sp. 및 Pseudomonas sp.와 64, 51, 47%의 상동성을, PstB 단백질은 Methanocaldococcus sp., E. coli 및 Mycoplasma sp.와 60, 50, 48%의 상동성을 나타내었다. Pst 유전자들은 조절영역의 cAMP-CRP 복합체에 의해 in vivo에서 양성적으로 발현됨을 확인하였다. Pst 오페론을 포함하는 플라스미드를 도입한 대장균은 인산운송에 관여하는 능력을 확인하였다.
A recombinant plasmid, pDH3, was obtained from the genomic library of Serattia marcescens KCTC 2172, and several recombinant subclones constructed from pDH3. The nucleotide sequence of a 5,137 bp segment, pPH4, was determined and three open reading frames were detected. The three ORFs encoded the phosphate specific transport (pst) operon, which was pstC, pstA, and pstB, with the same direction of transcription. Comparison of the pst operon of S. marcescens with that of other organisms revealed that the genes for pstS and phoU were missing. A potential CRP bonding site and pho box sequence was found in the upstream of the putative promoter at the regulatory region. Analysis of the nucleotide sequence showed that homology in amino acid sequences between the PstC protein and Yersinia sp., Vibrio sp., and Pseudomonas sp. were 49, 37 and 33%, respectively. The PstA protein and Yersinia sp., Vibrio sp., and Pseudomonas sp. showed homologies of 64, 51, and 47%, respectively. PstB protein and Methanocaldococcus sp., E. coli, and Mycoplasma sp. showed homologies of 60, 50, and 48%, respectively. The pst genes could be expressed in vivo and positively regulated by cAMP-CRP. The E. coli strain harboring plasmid pPH7, with pst genes, increased with the transport of phosphate.
