芽孢杆菌脱乙酰酶的交叉功能涉及杆菌硫醇的生物合成和细菌硫醇-S-共轭物的解毒途径。,Biochemical Journal

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芽孢杆菌脱乙酰酶的交叉功能涉及杆菌硫醇的生物合成和细菌硫醇-S-共轭物的解毒途径。
Biochemical Journal ( IF 4.4 ) Pub Date : 2013-06-14 , DOI: 10.1042/bj20130415
Zhong Fang ₁ , Alexandra A Roberts , Karissa Weidman , Sunil V Sharma , Al Claiborne , Christopher J Hamilton , Patricia C Dos Santos

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BshB是细菌硫醇生物合成中的关键酶，可水解苹果酸N-乙酰氨基葡萄糖中的乙酰基，生成苹果酸氨基葡萄糖。在炭疽芽孢杆菌中，BA1557被鉴定为N-乙酰氨基葡萄糖苹果酸脱乙酰基酶（BshB）；然而，在炭疽芽孢杆菌∆BA1557菌株中仍观察到了高含量的乙硫醇（〜70％）。基因组分析提出了另一种脱乙酰基酶可以在乙硫醇生物合成中表现出交叉功能的提议。在本研究中，BA1557，其旁系同源物BA3888和直系芽孢杆菌BC1534和BC3461对N-乙酰氨基葡萄糖苹果酸的脱乙酰酶活性得到了表征，从而为该提议提供了生化证据。此外，脱乙酰基酶的参与也有望通过硫巯基加合物的形成而在乙硫醇解毒途径中发挥作用。杆菌硫醇-S-双马胺结合物的动力学分析有利于BA3888作为炭疽芽孢杆菌杆菌硫醇-S-结合物酰胺酶（Bca）的参与。这组酶对其生理底物的高度特异性，以及它们相似的pH活性和依赖Zn 2+的催化酸碱反应，为它们的交叉功能提供了进一步的证据。

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Cross-functionalities of Bacillus deacetylases involved in bacillithiol biosynthesis and bacillithiol-S-conjugate detoxification pathways.

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 (~70%) was still observed in the B. anthracis ∆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.

更新日期：2019-11-01

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