Abstract:
:Delta 6 desaturase (FADS2) is a critical bifunctional enzyme required for PUFA biosynthesis. In some organisms, FADS2s have high substrate specificity, whereas in others, they have high catalytic activity. Previously, we analyzed the molecular mechanisms underlying high FADS2 substrate specificity; in this study, we assessed those underlying the high catalytic activity of FADS2s from Glossomastix chrysoplasta and Thalassiosira pseudonana To understand the structural basis of this catalytic activity, GcFADS2 and TpFADS2 sequences were divided into nine sections, and a domain-swapping approach was applied to examine the role of each section in facilitating the catalytic activity of the overall protein. The results revealed two regions essential to this process: one that extends from the end of the fourth to the beginning of the fifth cytoplasmic transmembrane domain, and another that includes the C-terminal region that occurs after the sixth cytoplasmic transmembrane domain. Based on the domain-swapping analyses, the amino acid residues at ten sites were identified to differ between the GcFADS2 and TpFADS2 sequences, and therefore further analyzed by site-directed mutagenesis. T302V, S322A, Y375F, and M384S/M385 substitutions in TpFADS2 significantly affected FADS2 catalytic efficiency. This study offers a solid basis for in-depth understanding of catalytic efficiency of FADS2.
journal_name
J Lipid Resjournal_title
Journal of lipid researchauthors
Shi 史海粟 H,Wu 乌日娜 R,Zheng 郑艳 Y,Yue 岳喜庆 Xdoi
10.1194/jlr.M079806subject
Has Abstractpub_date
2018-01-01 00:00:00pages
79-88issue
1eissn
0022-2275issn
1539-7262pii
jlr.M079806journal_volume
59pub_type
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