Dataset Information

Lipid-mediated unfolding of 3?-hydroxysteroid dehydrogenase 2 is essential for steroidogenic activity.

ABSTRACT: For inner mitochondrial membrane (IMM) proteins that do not undergo N-terminal cleavage, the activity may occur in the absence of a receptor present in the mitochondrial membrane. One such protein is human 3?-hydroxysteroid dehydrogenase 2 (3?HSD2), the IMM resident protein responsible for catalyzing two key steps in steroid metabolism: the conversion of pregnenolone to progesterone and dehydroepiandrosterone to androstenedione. Conversion requires that 3?HSD2 serve as both a dehydrogenase and an isomerase. The dual functionality of 3?HSD2 results from a conformational change, but the trigger for this change remains unknown. Using fluorescence resonance energy transfer, we found that 3?HSD2 interacted strongly with a mixture of dipalmitoylphosphatidylglycerol (DPPG) and dipalmitoylphosphatidylcholine (DPPC). 3?HSD2 became less stable when incubated with the individual lipids, as indicated by the decrease in thermal denaturation (T(m)) from 42 to 37 °C. DPPG, alone or in combination with DPPC, led to a decrease in ?-helical content without an effect on the ?-sheet conformation. With the exception of the 20 N-terminal amino acids, mixed vesicles protected 3?HSD2 from trypsin digestion. However, protein incubated with DPPC was only partially protected. The lipid-mediated unfolding completely supports the model in which a cavity forms between the ?-helix and ?-sheet. As 3?HSD2 lacks a receptor, opening the conformation may activate the protein.

SUBMITTER: Rajapaksha M

PROVIDER: S-EPMC3399592 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Lipid-mediated unfolding of 3β-hydroxysteroid dehydrogenase 2 is essential for steroidogenic activity.

Rajapaksha Maheshinie M Thomas James L JL Streeter Michael M Prasad Manoj M Whittal Randy M RM Bell John D JD Bose Himangshu S HS

Biochemistry 20111206 51

For inner mitochondrial membrane (IMM) proteins that do not undergo N-terminal cleavage, the activity may occur in the absence of a receptor present in the mitochondrial membrane. One such protein is human 3β-hydroxysteroid dehydrogenase 2 (3βHSD2), the IMM resident protein responsible for catalyzing two key steps in steroid metabolism: the conversion of pregnenolone to progesterone and dehydroepiandrosterone to androstenedione. Conversion requires that 3βHSD2 serve as both a dehydrogenase and a ...[more]

PMID: 22106846

Similar Datasets

Project description:BACKGROUND: Epi-testosterone (epiT) is the 17alpha-epimer of testosterone. It has been found at similar level as testosterone in human biological fluids. This steroid has thus been used as a natural internal standard for assessing testosterone abuse in sports. EpiT has been also shown to accumulate in mammary cyst fluid and in human prostate. It was found to possess antiandrogenic activity as well as neuroprotective effects. So far, the exact pathway leading to the formation of epiT has not been elucidated. RESULTS: In this report, we describe the isolation and characterization of the enzyme 17alpha-hydroxysteroid dehydrogenase. The name is given according to its most potent activity. Using cells stably expressing the enzyme, we show that 17alpha-HSD catalyzes efficienty the transformation of 4-androstenedione (4-dione), dehydroepiandrosterone (DHEA), 5alpha-androstane-3,17-dione (5alpha-dione) and androsterone (ADT) into their corresponding 17alpha-hydroxy-steroids : epiT, 5-androstene-3beta,17alpha-diol (epi5diol), 5alpha-androstane-17alpha-ol-3-one (epiDHT) and 5alpha-androstane-3alpha,17alpha-diol (epi3alpha-diol), respectively. Similar to other members of the aldo-keto reductase family that possess the ability to reduce the keto-group into hydroxyl-group at different position on the steroid nucleus, 17alpha-HSD could also catalyze the transformation of DHT, 5alpha-dione, and 5alpha-pregnane-3,20-dione (DHP) into 3alpha-diol, ADT and 5alpha-pregnane-3alpha-ol-20-one (allopregnanolone) through its less potent 3alpha-HSD activity. We also have over-expressed the 17alpha-HSD in Escherichia coli and have purified it by affinity chromatography. The purified enzyme exhibits the same catalytic properties that have been observed with cultured HEK-293 stably transfected cells. Using quantitative Realtime-PCR to study tissue distribution of this enzyme in the mouse, we observed that it is expressed at very high levels in the kidney. CONCLUSION: The present study permits to clarify the biosynthesis pathway of epiT. It also offers the opportunity to study gene regulation and function of this enzyme. Further study in human will allow a better comprehension about the use of epiT in drug abuse testing; it will also help to clarify the importance of its accumulation in breast cyst fluid and prostate, as well as its potential role as natural antiandrogen.

Dataset Information

Lipid-mediated unfolding of 3?-hydroxysteroid dehydrogenase 2 is essential for steroidogenic activity.

Publications

Lipid-mediated unfolding of 3β-hydroxysteroid dehydrogenase 2 is essential for steroidogenic activity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure