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Overexpression and characterization of dimeric and tetrameric forms of recombinant serine hydroxymethyltransferase from <BI>Bacillus stearothermophilus<B>.

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Title Overexpression and characterization of dimeric and tetrameric forms of recombinant serine hydroxymethyltransferase from Bacillus stearothermophilus.
 
Creator Venkatakrishna Jala, R.
Prakash, V.
Appaji Rao, N.
Savithri, H. S.
 
Subject 16 Enzyme Chemistry
 
Description Serine hydroxymethyltransferase (SHMT), a pyridoxal-5¢-phosphate (PLP) dependent enzyme catalyzes the
interconversion of L-Ser and Gly using tetrahydrofolate as a substrate. The gene encoding for SHMT was amplified by PCR from genomic DNA of Bacillus stearothermophilus and the PCR product was cloned and overexpressed in Escherichia coli. The purified recombinant enzyme was isolated as a mixture of dimer (90%) and tetramer (10%). This is the first report demonstrating the existence of SHMT as a dimer and tetramer in the same organism. The specific activities at 37°C of the dimeric and tetrameric forms were 6×7 U/mg and 4×1 U/mg, respectively. The purified dimer was extremely thermostable with a Tm of 85°C in the presence of
PLP and L-Ser. The temperature optimum of the dimer was 80°C with a specific activity of 32×4 U/mg at this
temperature. The enzyme catalyzed tetrahydrofolate-independent reactions at a slower rate compared to the
tetrahydrofolate-dependent retro-aldol cleavage of L-Ser. The interaction with substrates and their analogues
indicated that the orientation of PLP ring of B. stearothermophilus SHMT was probably different from sheep
liver cytosolic recombinant SHMT (scSHMT).
 
Date 2002
 
Type Article
NonPeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://ir.cftri.com/2802/1/J_Biosci_2002_27_3_233-242.pdf
Venkatakrishna Jala, R. and Prakash, V. and Appaji Rao, N. and Savithri, H. S. (2002) Overexpression and characterization of dimeric and tetrameric forms of recombinant serine hydroxymethyltransferase from <BI>Bacillus stearothermophilus<B>. Journal of Bioscience, 27 (3). pp. 233-242.