In vivo and in vitro studies of Bacillus subtilis ferrochelatase mutants suggest substrate channeling in the heme biosynthesis pathway.
In vivo and in vitro studies of Bacillus subtilis ferrochelatase mutants suggest substrate channeling in the heme biosynthesis pathway.
复制标题
枯草芽孢杆菌铁螯合酶突变体的体内和体外研究表明血红素生物合成途径中存在底物通道。
作者：
U. Olsson;Annika Billberg;S. Sjövall;S. Al;M. Hansson
螯合铁酶（EC 4.99.1.1）催化血红素生物合成途径的最后一个反应。该酶在枯草芽孢杆菌中进行了研究，其中铁螯合酶的三维结构是已知的。两个保守的氨基酸残基，S54和Q63，通过定点诱变被改变为丙氨酸，以检测它们可能具有的任何功能。在体内和体外研究了这些变化的影响。S54和Q63都位于螺旋alpha3上。S54的官能团指向酶，而Q63位于结构内部。这些残基都不与铁螯合酶中的其他氨基酸残基相互作用，它们的功能也无法从三维结构上理解。交换物S54A降低了枯草芽孢杆菌的生长速度，导致生长培养基中coproporphyrin III的积累，而Q63A则没有。这与纯化酶的体外活性测量结果形成对比。交换物为S54A的铁螯合酶活性与野生型一样，而交换物为Q63A则使V（max）降低了16倍。Q63的功能尚不清楚，但提示S54参与酶产物的底物接收或传递。
Ferrochelatase (EC 4.99.1.1) catalyzes the last reaction in the heme biosynthetic pathway. The enzyme was studied in the bacterium Bacillus subtilis, for which the ferrochelatase three-dimensional structure is known. Two conserved amino acid residues, S54 and Q63, were changed to alanine by site-directed mutagenesis in order to detect any function they might have. The effects of these changes were studied in vivo and in vitro. S54 and Q63 are both located at helix alpha3. The functional group of S54 points out from the enzyme, while Q63 is located in the interior of the structure. None of these residues interact with any other amino acid residues in the ferrochelatase and their function is not understood from the three-dimensional structure. The exchange S54A, but not Q63A, reduced the growth rate of B. subtilis and resulted in the accumulation of coproporphyrin III in the growth medium. This was in contrast to the in vitro activity measurements with the purified enzymes. The ferrochelatase with the exchange S54A was as active as wild-type ferrochelatase, whereas the exchange Q63A caused a 16-fold reduction in V(max). The function of Q63 remains unclear, but it is suggested that S54 is involved in substrate reception or delivery of the enzymatic product.
影响因子：
2.9
作者：
FLING, SP;GREGERSON, DS
通讯作者：
GREGERSON, DS
通过辐射灭活原位测定亚铁螯合酶的功能大小。
DOI：
--
发表时间：
1991
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Straka,JG;Bloomer,JR;Kempner,ES
通讯作者：
Kempner,ES
卟啉症的血液学方面。
DOI：
--
发表时间：
2000
期刊：
International journal of hematology.
影响因子：
--
作者：
Sassa,S
通讯作者：
Sassa,S