Substrate Specificity in Thiol Dioxygenases
Substrate Specificity in Thiol Dioxygenases
复制标题
DOI：
10.1021/acs.biochem.9b00079
复制
发表时间：
2019-05-14
期刊：
影响因子：
2.9
通讯作者：
Jameson, Guy N. L.
中科院分区：
文献类型：
--
作者：
Aloi, Sekotilani;Davies, Casey G.;Jameson, Guy N. L.
硫醇双加氧酶构成一类亚铁依赖性酶，其将硫醇氧化成其相应的亚磺酸盐。半胱氨酸结合的半胱氨酸双加氧酶的X射线衍射结构显示了半胱氨酸如何通过其硫醇盐和胺与铁配位，并正确定向以进行O原子转移。目前还没有3-巯基丙酸或巯基琥珀酸与它们各自的酶（3-巯基丙酸双加氧酶或巯基琥珀酸双加氧酶）结合的结构。已知结构的序列比对和比较使我们假设定义底物特异性的关键结构特征。在这里，我们比较了褐家鼠半胱氨酸双加氧酶和3-巯基丙酸双加氧酶从铜绿假单胞菌和Ralstonia eutropha（JMP 134）的变体的速率和反应性，并显示了三种结构特征的二元变体如何与底物特异性和反应性相关。它们是（1）残基Ser 158和Pro 159之间是否存在顺式-肽键，（2）位置60处的Arg或Gln，和（3）位置164处的Cys或Arg（均为RnCDO编号）。这些特征的不同排列允许促进或阻碍L-半胱氨酸、3-巯基丙酸和（R）-巯基琥珀酸的亚磺化。
Thiol dioxygenases make up a class of ferrous iron-dependent enzymes that oxidize thiols to their corresponding sulfinates. X-ray diffraction structures of cysteine-bound cysteine dioxygenase show how cysteine is coordinated via its thiolate and amine to the iron and oriented correctly for O atom transfer. There are currently no structures with 3-mercaptopropionic acid or mercaptosuccinic acid bound to their respective enzymes, 3-mercaptopropionate dioxygenase or mercaptosuccinate dioxygenase. Sequence alignments and comparisons of known structures have led us to postulate key structural features that define substrate specificity. Here, we compare the rates and reactivities of variants of Rattus norvegicus cysteine dioxygenase and 3-mercaptopropionate dioxygenases from Pseudomonas aureginosa and Ralstonia eutropha (JMP134) and show how binary variants of three structural features correlate with substrate specificity and reactivity. They are (1) the presence or absence of a cis-peptide bond between residues Ser158 and Pro159, (2) an Arg or Gln at position 60, and (3) a Cys or Arg at position 164 (all RnCDO numbering). Different permutations of these features allow sulfination of L-cysteine, 3-mercaptopropionic acid, and (R)-mercaptosuccinic acid to be promoted or impeded.