کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2185274 1095970 2011 16 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Crystal Structures and Enzymatic Properties of a Triamine/Agmatine Aminopropyltransferase from Thermus thermophilus
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
Crystal Structures and Enzymatic Properties of a Triamine/Agmatine Aminopropyltransferase from Thermus thermophilus
چکیده انگلیسی

To maintain functional conformations of DNA and RNA in high-temperature environments, an extremely thermophilic bacterium, Thermus thermophilus, employs a unique polyamine biosynthetic pathway and produces more than 16 types of polyamines. In the thermophile genome, only one spermidine synthase homolog (SpeE) was found and it was shown to be a key enzyme in the pathway. The catalytic assay of the purified enzyme revealed that it utilizes triamines (norspermidine and spermidine) and agmatine as acceptors in its aminopropyl transfer reaction; therefore, the enzyme was denoted as a triamine/agmatine aminopropyltransferase (TAAPT). We determined the crystal structures of the enzyme complexed with and without the aminopropyl group donor S-adenosylmethionine. Despite sequence and structural similarity with spermidine synthases from other organisms, a novel C-terminal β-sheet and differences in the catalytic site were observed. The C-terminal module interacts with the gatekeeping loop and fixes the open conformation of the loop to recognize larger polyamine substrates such as agmatine and spermidine. Additional computational docking studies suggest that the structural differences of the catalytic site also contribute to recognition of the aminopropyl/aminobutyl or guanidium moiety of the substrates of TAAPT. These results explain in part the extraordinarily diverse polyamine spectrum found in T. thermophilus.

Graphical AbstractFigure optionsDownload high-quality image (100 K)Download as PowerPoint slideResearch Highlights
► Thermus thermophilus employs a unique polyamine biosynthetic pathway.
► We present structures of aminopropyltranserase (TtTAAPT), a key enzyme of the pathway.
► Polyamine binding cavity is larger than other known spermidine synthases.
► C-terminal module interacts with the loop of the lid of the catalytic cleft.
► These features contribute to recognition of agmatine and triamines instead of putrescine.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Biology - Volume 408, Issue 5, 20 May 2011, Pages 971–986
نویسندگان
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