Interdisciplinary Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan.
Biological Science Laboratories, Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi 321-3497, Japan.
J Biol Chem. 2012 Mar 23;287(13):9765-9776. doi: 10.1074/jbc.M111.329490. Epub 2012 Jan 25.
Cell wall metabolism and cell wall modification are very important processes that bacteria use to adjust to various environmental conditions. One of the main modifications is deacetylation of peptidoglycan. The polysaccharide deacetylase homologue, Bacillus subtilis YjeA (renamed PdaC), was characterized and found to be a unique deacetylase. The pdaC deletion mutant was sensitive to lysozyme treatment, indicating that PdaC acts as a deacetylase. The purified recombinant and truncated PdaC from Escherichia coli deacetylated B. subtilis peptidoglycan and its polymer, (-GlcNAc-MurNAc[-L-Ala-D-Glu]-)(n). Surprisingly, RP-HPLC and ESI-MS/MS analyses showed that the enzyme deacetylates N-acetylmuramic acid (MurNAc) not GlcNAc from the polymer. Contrary to Streptococcus pneumoniae PgdA, which shows high amino acid sequence similarity with PdaC and is a zinc-dependent GlcNAc deacetylase toward peptidoglycan, there was less dependence on zinc ion for deacetylation of peptidoglycan by PdaC than other metal ions (Mn(2+), Mg(2+), Ca(2+)). The kinetic values of the activity toward B. subtilis peptidoglycan were K(m) = 4.8 mM and k(cat) = 0.32 s(-1). PdaC also deacetylated N-acetylglucosamine (GlcNAc) oligomers with a K(m) = 12.3 mM and k(cat) = 0.24 s(-1) toward GlcNAc(4). Therefore, PdaC has GlcNAc deacetylase activity toward GlcNAc oligomers and MurNAc deacetylase activity toward B. subtilis peptidoglycan.
细胞壁代谢和细胞壁修饰是细菌用来适应各种环境条件的非常重要的过程。其中主要的修饰之一是肽聚糖脱乙酰化。多糖脱乙酰酶同源物枯草芽孢杆菌 YjeA（更名为 PdaC）被表征为一种独特的脱乙酰酶。pdaC 缺失突变体对溶菌酶处理敏感，表明 PdaC 作为脱乙酰酶发挥作用。从大肠杆菌中纯化的重组和截断的 PdaC 使枯草芽孢杆菌的肽聚糖及其聚合物（-GlcNAc-MurNAc[-L-Ala-D-Glu]-）（n）脱乙酰化。令人惊讶的是，RP-HPLC 和 ESI-MS/MS 分析表明，该酶从聚合物中脱乙酰化 N-乙酰基胞壁酸（MurNAc）而不是 GlcNAc。与肺炎链球菌 PgdA 不同，PdaC 与 PgdA 具有高度的氨基酸序列相似性，是一种锌依赖性的肽聚糖 GlcNAc 脱乙酰酶，而 PdaC 对肽聚糖的脱乙酰化作用对锌离子的依赖性低于其他金属离子（Mn(2+)、Mg(2+)、Ca(2+)）。对枯草芽孢杆菌肽聚糖的活性的动力学值为 K(m) = 4.8 mM 和 k(cat) = 0.32 s(-1)。PdaC 还使 N-乙酰葡萄糖胺（GlcNAc）低聚物脱乙酰化，K(m) = 12.3 mM，k(cat) = 0.24 s(-1)，对 GlcNAc(4)。因此，PdaC 对 GlcNAc 低聚物具有 GlcNAc 脱乙酰酶活性，对枯草芽孢杆菌的肽聚糖具有 MurNAc 脱乙酰酶活性。
