Title:The 3-Oxoacyl-(Acyl-Carrier-Protein) Reductase HSD-X1 of Pseudomonas
Citronellolis SJTE-3 Catalyzes the Conversion of 17β-estradiol to Estrone
Volume: 29
Issue: 3
Author(s): Yali Fu, Wanli Peng, Shuangjun Lin, Zixin Deng and Rubing Liang*
Affiliation:
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong
University, Shanghai200240, China
Keywords:
Pseudomonas citronellolis SJTE-3, 3-oxoacyl-ACP reductase, 17β-hydroxysteroid dehydrogenase, 17β-estradiol, estrone, MSA, E2 metabolism.
Abstract:
Background: Pseudomonas citronellolis SJTE-3 can efficiently degrade 17β-estradiol
(E2) and other estrogenic chemicals. However, the enzyme responsible for E2 metabolism within
strain SJTE-3 has remained unidentified.
Objective: Here, a novel 3-oxoacyl-(acyl-carrier protein) (ACP) reductase, HSD-X1 (WP_
009617962.1), was identified in SJTE-3 and its enzymatic characteristics for the transformation
of E2 were investigated.
Methods: Multiple sequence alignment and homology modelling were used to predict the protein
structure of HSD-X1. The concentrations of different steroids in the culture of recombinant strains
expressing HSD-X1 were determined by high performance liquid chromatography. Additionally,
the transcription of hsd-x1 gene was investigated using reverse transcription and quantitative PCR
analysis. Heterologous expression and affinity purification were used to obtain recombinant HSD-
X1.
Results: The transcription of hsd-x1 gene in P. citronellolis SJTE-3 was induced by E2. Multiple
sequence alignment (MSA) indicated that HSD-X1 contained the two consensus regions and
conserved residues of short-chain dehydrogenase/reductases (SDRs) and 17β-hydroxysteroid dehydrogenases
(17β-HSDs). Over-expression of hsd-x1 gene allowed the recombinant strain to degrade
E2. Recombinant HSD-X1 was purified with a yield of 22.15 mg/L and used NAD+ as its cofactor
to catalyze the oxidization of E2 into estrone (E1) while exhibiting a Km value of 0.025 ±
0.044 mM and a Vmax value of 4.92 ± 0.31 mM/min/mg. HSD-X1 could tolerate a wide range of
temperature and pH, while the presence of divalent ions exerted little influence on its activity. Further,
the transformation efficiency of E2 into E1 was over 98.03% across 15 min.
Conclusion: Protein HSD-X1 efficiently catalyzed the oxidization of E2 and participated in estrogen
degradation by P. citronellolis SJTE-3.