Cross-functionalities of Bacillus deacetylases involved in bacillithiol biosynthesis and bacillithiol-S-conjugate detoxification pathways
Cross-functionalities of Bacillus deacetylases involved in bacillithiol biosynthesis and bacillithiol-S-conjugate detoxification pathways
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DOI：
10.1042/bj20130415
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发表时间：
2013-09-01
影响因子：
4.1
通讯作者：
Dos Santos, Patricia C.
中科院分区：
文献类型：
--
作者：
Fang, Zhong;Roberts, Alexandra A.;Dos Santos, Patricia C.
BshB是细菌硫醇生物合成中的关键酶，其水解N-乙酰氨基葡萄糖苹果酸的乙酰基以生成氨基葡萄糖苹果酸。在炭疽芽孢杆菌中，BA 1557已被鉴定为N-乙酰葡糖胺苹果酸脱乙酰酶（Bsh B）;然而，在B中仍观察到高含量的杆菌硫醇（类似于70%）。炭疽杆菌Delta BA 1557菌株。基因组分析导致另一种脱乙酰酶可能在bacillithiol生物合成中表现出交叉功能的提议。本研究对BA 1557及其副产物BA 3888和正芽孢杆菌蜡样芽孢杆菌（Bacilluscereus）酶BC 1534和BC 3461的N-乙酰氨基葡萄糖苹果酸脱乙酰酶活性进行了表征，从而为这一提议提供了生化证据。此外，脱乙酰酶的参与也预期在杆菌锂硫醇解毒途径通过形成S-巯基尿酸加合物。对杆菌锂-S-bimane偶联物的动力学分析支持BA 3888作为B参与。炭疽杆菌硫锂-S-共轭酰胺酶（Bca）。这组酶对其生理底物的高度特异性，沿着它们相似的pH-活性特征和Zn 2+依赖性催化酸碱反应，为它们的交叉功能性提供了进一步的证据。
BshB, a key enzyme in bacillithiol biosynthesis, hydrolyses the acetyl group from N-acetylglucosamine malate to generate glucosamine malate. In Bacillus anthracis, BA1557 has been identified as the N-acetylglucosamine malate deacetylase (BshB); however, a high content of bacillithiol (similar to 70%) was still observed in the B. anthracis Delta BA1557 strain. Genomic analysis led to the proposal that another deacetylase could exhibit cross-functionality in bacillithiol biosynthesis. In the present study, BA1557, its paralogue BA3888 and orthologous Bacillus cereus enzymes BC1534 and BC3461 have been characterized for their deacetylase activity towards N-acetylglucosamine malate, thus providing biochemical evidence for this proposal. In addition, the involvement of deacetylase enzymes is also expected in bacillithiol-detoxifying pathways through formation of S-mercapturic adducts. The kinetic analysis of bacillithiol-S-bimane conjugate favours the involvement of BA3888 as the B. anthracis bacillithiol-S-conjugate amidase (Bca). The high degree of specificity of this group of enzymes for its physiological substrate, along with their similar pH-activity profile and Zn2+-dependent catalytic acid-base reaction provides further evidence for their cross-functionalities.