Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/38421
標題: Effects of substrate and potassium on the betaine-synthesizing enzyme glycine sarcosine dimethylglycine N-methyltransferase from a halophilic methanoarchaeon Methanohalophilus portucalensis
作者: Lai, M.C.
賴美津
Wang, C.C.
Chuang, M.J.
Wu, Y.C.
Lee, Y.C.
關鍵字: de novo betaine synthesis
compatible solutes
glycine
N-methyltransferase
glycine sarcosine dimethylglycine
methyltransferase
halophilic methanoarchaea
compatible solutes
methanogenic archaebacteria
aphanothece-halophytica
organic osmolytes
rat-liver
lysine
osmoadaptation
osmoregulation
diversity
pathways
期刊/報告no:: Research in Microbiology, Volume 157, Issue 10, Page(s) 948-955.
摘要: Methanohalophilus portucalensis FDF1 can synthesize the compatible solute betaine de novo through the methylation of glycine, sarcosine and dimethylglycine with the methyl group from S-adenosylmethionine. After separation by DEAE-Sephacel ion chromatography using a KCl step gradient, glycine, sarcosine and dimethylglycine methytransfer (GSDMT) activities were detected in a single peak. The estimated molecular weight of GSDMT was 240 kDa and 2-D gel analysis indicated it was separated into four subunits (52 kDa) with different pI. The PBE94 chromatofocusing column also separated GSDMT into four protein peaks A, B, C, D. Both peak B and D proteins possessed GSDMT activity, while the peak A protein only exhibited SDMT activity. The multiple methyltransferase activities of the large complex appear to be unique compared to other methyltransferases used in betaine synthesis. Further methyltransferase assays in response to different concentrations of KCl indicated that the peak D protein exhibited low GSDMT activity only when K+ <= 0.4 M. The peak B protein exhibited a higher GSDMT activity at 0.4 M K+, while the peak A protein exhibited SDMT activity only at higher K+ (0.8 M). These results suggest that the internal K+ concentration regulates GSDMT activities and affects the net betaine accumulation in the cells. (c) 2006 Elsevier Masson SAS. All rights reserved.
URI: http://hdl.handle.net/11455/38421
ISSN: 0923-2508
文章連結: http://dx.doi.org/10.1016/j.resmic.2006.08.007
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