| Molecular probing of the Saccharomyces cerevisiae sterol 24-C methyltransferase reveals multiple amino acid residues involved with C2-transfer activity. | |
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MedLine Citation:
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PMID: 18503783 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Two families of sterol C24-methyltransferase (SMT) are responsible for the formation of the ergostane (C(1)-transfer activity; SMT1) and stigmastane (C(2)-transfer activity: SMT2) sterol side chains, respectively. The fungal Saccharomyces cerevisiae SMT1 (Erg6p) operates the first C(1)-transfer in concerted fashion to form a single product whereas the protozoan and plant SMTs are bifunctional capable of catalyzing two sequential, mechanistically distinct C-methylation activities in the conversion of a Delta(24)-sterol acceptor to diverse doubly alkylated products. Previous mutation of the amino acids of Erg6p at D79, Y81 and E82 afforded C(1) or C(2)-transfer activities typical of the protozoan and plant SMT. In this study, scanning mutagenesis experiments involving a leucine replacement of 52 amino acids in Erg6p followed by substitution of key residues with functionally or structurally similar amino acids indicated that 5 new residues at positions Y192, G217, G218, T219 and Y223 can switch the course of C(1)-transfer activity to include plant-like C(2)-transfer activity. The data support a model in which several conserved and non-conserved amino acids located in distinct regions of the Erg6p regulate the course of the C-methylation reaction toward product differences. |
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Authors:
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Kulothungan Ganapathy; Christopher W Jones; Camille M Stephens; Rit Vatsyayan; Julie A Marshall; W David Nes |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2008-05-08 |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 1781 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 2008 Jun-Jul |
Date Detail:
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Created Date: 2008-06-23 Completed Date: 2008-08-15 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: Netherlands |
Other Details:
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Languages: eng Pagination: 344-51 Citation Subset: IM |
Affiliation:
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Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Sequence Amino Acids / chemistry* Methyltransferases / chemistry, genetics, metabolism* Molecular Probes* Molecular Sequence Data Mutagenesis Saccharomyces cerevisiae / enzymology* Sequence Homology, Amino Acid |
| Chemical | |
Reg. No./Substance:
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0/Amino Acids; 0/Molecular Probes; EC 2.1.1.-/Methyltransferases; EC 2.1.1.41/delta 24-sterol methyltransferase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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