Browsing by Author "Venkatesan, Nandinin"

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Identification of amino acid residues important for the phosphomannose isomerase activity of Ps1B in Pseudomonas aeruginosa PAO1
(2008-10-15)
Lee, Hui-Ju
;
Chang, Hwan-You
;
Venkatesan, Nandinin
;
Peng, Hwei-Ling
;
生物科技學院
Phosphomannose isomerase (PMI) plays a pivotal role in biosynthesis of GDP-mannose, an important precursor of many polysaccharides. We demonstrate in this study that Pseudomonas aeruginosa pslB encodes a protein with GDP-mannose pyrophosphorylase/PMI dual activities. The PMI activity is Co2+-dependent and could be inhibited by GDP-mannose in a competitive manner. Furthermore, the activity could be inactivated by 2,3-butanedione suggesting the presence of a catalytic Arg residue. Site-specific mutations at R373, R472, R479, E410, H411, N433 and E458 increase the KM approximately 8-20-fold. The PMI activity of PslB was completely diminished with a R408K or R408A, reflecting the importance of this residue in catalysis. Overall, these results provide a basis for understanding the catalytic mechanism of PMI.