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Shirazi, Taraneh, 2013. Oxysterols inhibit plant Sterol methyl transferase type-1 enzyme activity in vitro . Second cycle, A2E. Uppsala: SLU, Dept. of Plant Biology and Forest Genetics (until 131231)



Sterols are important structural components of eukaryotic cell membranes, where they influence membrane fluidity and permeability. Sterols contain a four-ring structure with a hydrocarbon side-chain. The sterol composition and structure differs among plants, mammals and fungi. Mammals and fungi contain a single main sterol such as cholesterol or ergosterol, respectively. In contrast, plants contain a mixture of several sterols with varying side-chain length such as sitosterol, stigmasterol and 24-methyl cholesterol. Side-chain length is regulated by the two enzymes, Sterol methyl transferase type-1 (SMT1) and type-2 (SMT2) which increase side-chain length by a methyl (SMT1) or ethyl (SMT2) group. Thus, regulation of SMT enzyme activity is crucial for sterol composition in plants.

This project considers to what extent oxysterols, oxidized sterol forms, can regulate SMT1 activity. SMT1 activity was assayed in microsome preparations from three plant species, and different oxysterols were added to the enzyme reaction to investigate the effect on enzyme activity. Results showed that oxysterols inhibited SMT1 activity in all plant species tested. The inhibitory effect was stronger for side-chain oxysterols (24-OH and 25-OH cholesterol) than for ring hydroxylated ones (7β-OH cholesterol). The results suggest that oxysterols have an inhibitory effect on SMT1 activity in plants, and may be part of a feed-back regulation of sterol composition.

Main title:Oxysterols inhibit plant Sterol methyl transferase type-1 enzyme activity in vitro
Authors:Shirazi, Taraneh
Supervisor:Sitbon, folke
Examiner:Meijer, Johan
Series:Examensarbete / Institutionen för växtbiologi och skogsgenetik, SLU
Volume/Sequential designation:139
Year of Publication:2013
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:NM003 Biotechnology - Master's Programme 120 HEC
Supervising department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Keywords:oxysterol, sterol, sterol methyl transferase, plant secondary metabolism
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Plant physiology and biochemistry
Deposited On:20 Jun 2013 08:53
Metadata Last Modified:18 Nov 2023 02:32

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