TY - JOUR
T1 - Escherichia coli YrbH is a D-arabinose 5-phosphate isomerase
AU - Meredith, Timothy C.
AU - Woodard, Ronald W.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2003/8/29
Y1 - 2003/8/29
N2 - A gene encoding for arabinose 5-phosphate isomerase (API), which catalyzes the interconversion of D-ribulose 5-phosphate (Ru5P) and D-arabinose 5-phosphate (A5P), has been identified from the genome of Escherichia coli K-12. API is the first enzyme in the biosynthesis of 3-deoxy-D-manno-octulosonate (KDO), a sugar moiety located in the lipopolysaccharide layer of most Gram-negative bacteria. The API gene yrbH is located next to the recently identified specific KDO 8-P phosphatase gene, yrbI. The 328-amino acid open reading frame yrbH was cloned, overexpressed, and characterized. The purified recombinant enzyme is a tetramer and is sensitive to inhibition by zinc cations. API has optimal activity at pH 8.4 and catalytic residues with estimated pKa values of 6.55 ± 0.04 and 10.34 ± 0.07. The enzyme is specific for A5P and Ru5P, with apparent Km values of 0.61 ± 0.06 mM for A5P and 0.35 ± 0.08 mM for Ru5P. The apparent k cat in the A5P to Ru5P direction is 157 ± 4 s-1, and in the Ru5P to A5P direction it is 255 ± 16 s-1. The value of Keq (Ru5P/A5P) is 0.50 ± 0.06. Homology searches of the E. coli genome suggest yrbH may be one of multiple genes that encode proteins with API activity.
AB - A gene encoding for arabinose 5-phosphate isomerase (API), which catalyzes the interconversion of D-ribulose 5-phosphate (Ru5P) and D-arabinose 5-phosphate (A5P), has been identified from the genome of Escherichia coli K-12. API is the first enzyme in the biosynthesis of 3-deoxy-D-manno-octulosonate (KDO), a sugar moiety located in the lipopolysaccharide layer of most Gram-negative bacteria. The API gene yrbH is located next to the recently identified specific KDO 8-P phosphatase gene, yrbI. The 328-amino acid open reading frame yrbH was cloned, overexpressed, and characterized. The purified recombinant enzyme is a tetramer and is sensitive to inhibition by zinc cations. API has optimal activity at pH 8.4 and catalytic residues with estimated pKa values of 6.55 ± 0.04 and 10.34 ± 0.07. The enzyme is specific for A5P and Ru5P, with apparent Km values of 0.61 ± 0.06 mM for A5P and 0.35 ± 0.08 mM for Ru5P. The apparent k cat in the A5P to Ru5P direction is 157 ± 4 s-1, and in the Ru5P to A5P direction it is 255 ± 16 s-1. The value of Keq (Ru5P/A5P) is 0.50 ± 0.06. Homology searches of the E. coli genome suggest yrbH may be one of multiple genes that encode proteins with API activity.
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U2 - 10.1074/jbc.M303661200
DO - 10.1074/jbc.M303661200
M3 - Article
C2 - 12805358
AN - SCOPUS:0042357436
VL - 278
SP - 32771
EP - 32777
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 35
ER -