tailieunhanh - Báo cáo khoa học: Structure determination and biochemical studies on Bacillus stearothermophilus E53Q serine hydroxymethyltransferase and its complexes provide insights on function and enzyme memory

Serine hydroxymethyltransferase (SHMT) belongs to the a-family of pyridoxal 5¢-phosphate-dependent enzymes and catalyzes the reversible conversion of l-Ser and tetrahydrofolate to Gly and 5,10-methylene tetrahydrofolate. 5,10-Methylene tetrahydrofolate serves as a source of one-carbon fragment in many biological processes. | ễFEBS Journal Structure determination and biochemical studies on Bacillus stearothermophilus E53Q serine hydroxymethyltransferase and its complexes provide insights on function and enzyme memory VRaiaram1 R s R h 5 55 n Í3 Pl I rn ima 1 551113 Prolzoeh3 M A n rvA i i Ran2 I I Ravithri2 and . najaiaiii D. o. LJiiavdn ruiiiiina I aui V. riaixaoii IM. -xppaji nau n. o. uaviuiii aiivi M. R. N. Murthy1 1 Molecular Biophysics Unit Indian Institute of Science Bangalore India 2 Department of Biochemistry Indian Institute of Science Bangalore India 3 Department of Protein Chemistry and Technology CentralFood TechnologicalResearch Institute Mysore India Keywords crystal structure enzyme memory pyridoxal5 -phosphate SHMT Correspondence M. R. N. Murthy Molecular Biophysics Unit Indian Institute of Science Bangalore 560 012 India Fax 91 80 2360 0535 Tel 91 80 2293 2458 E-mail mrn@ These authors contributed equally to this work Received 4 March 2007 revised 6 May 2007 accepted 14 June 2007 doi Serine hydroxymethyltransferase SHMT belongs to the a-family of pyridoxal 5 -phosphate-dependent enzymes and catalyzes the reversible conversion of L-Ser and tetrahydrofolate to Gly and 5 10-methylene tetrahydrofolate. 5 10-Methylene tetrahydrofolate serves as a source of one-carbon fragment in many biological processes. SHMT also catalyzes the tetrahydrofolate-independent conversion of L-allo-Thr to Gly and acetaldehyde. The crystal structure of Bacillus stearothermophilus SHMT bsSHMT suggested that E53 interacts with the substrate L-Ser and tetrahydrofolate. To elucidate the role of E53 it was mutated to Q and structural and biochemical studies were carried out with the mutant enzyme. The internal aldimine structure of E53QbsSHMT was similar to that of the wild-type enzyme except for significant changes at Q53 Y60 and Y61. The carboxyl of Gly and side chain of L-Ser were in two conformations in the respective external aldimine structures.

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