title: Structural characterization of Escherichia coli sialic acid synthase.
abstract: Sialic acid synthase encoded by the neuB gene of Escherichia coli catalyzes the condensation of N-acetylmannosamine and phosphoenolpyruvate to form N-acetylneuraminic acid. This report demonstrates the first structural information on sialic acid synthase by CD, MALDI-TOF, and chemical cross-linking studies. Also, a specific cleavage by endogenous protease(s) has been identified at Lys(280) of the enzyme (40 kDa) by LC-MS and N-terminal sequencing analyses. The cleavage results in the formation of two inactive fragments of 33 and 7 kDa. The structural analysis indicates that the fragmentation is associated with a significant change of the enzyme from a tetrameric to trimeric form, and alterations in both secondary and native quaternary structures.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, No. 128 Academia Road Sec. 2, Nan-Kang, Taipei 11529, Taiwan.
authors.forename: Tzann-Shun
authors.initials: TS
authors.lastname: Hwang
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Hung
authors.forename: Chin-Fen
authors.initials: CF
authors.lastname: Teo
authors.forename: Guan-Ting
authors.initials: GT
authors.lastname: Chen
authors.forename: Lee-Shang
authors.initials: LS
authors.lastname: Chang
authors.forename: Sung-Fang
authors.initials: SF
authors.lastname: Chen
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry; D002942:Circular Dichroism; D004926:Escherichia coli / Q000201:enzymology*; D007652:Oxo-Acid-Lyases / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: C020011:2-dehydro-3-deoxyphosphooctonate aldolase; C018730:N-acetylneuraminate synthase; D000446:Aldehyde-Lyases; D007652:Oxo-Acid-Lyases; C018728:N-acetylneuraminate lyase