Identification of significant residues for intermediate accumulation in phycocyanobilin synthesis
Identification of significant residues for intermediate accumulation in phycocyanobilin synthesis
复制标题
藻蓝蛋白合成中中间积累的重要残留物的鉴定
DOI：
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发表时间：
2022
影响因子：
3.1
通讯作者：
R. Narikawa
中科院分区：
文献类型：
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作者：
Keita Miyake;Hiroyuki Kimura;R. Narikawa
藻蓝胆素是蓝细菌中光感知和捕光的主要色素，由胆绿素IXα（BV）经中间体181，182-二氢胆绿素（181，182-DHBV）经藻蓝胆素：铁氧还蛋白氧化还原酶（PcyA）合成。在我们以前的研究中，我们发现了两个来源于Acaryochloris marina MBIC 11017（A. marina），其例外地使用叶绿素d作为主要的光合色素，吸收比叶绿素a更长波长的远红光，叶绿素a是在大多数蓝细菌中发现的光合色素。两个PcyA同源物的生物化学表征确定了这两种酶的功能多样化：AmPcyAc提供181，182-DHBV和PCB的蓝细菌色素（CBCR）光感受器，而AmPcyAp专门提供PCB的光捕获藻胆体亚基。在这项研究中，我们专注于181，182-DHBV供应到CBCR光感受器的AmPcyAc所必需的残基。基于SyPcyA结构，我们集中在构成底物结合口袋的30个残基上。其中，我们发现AmPcyAc中的Leu 151和Val 225都被异亮氨酸取代。在酶促反应过程中，具有V225 I和L151 I置换的SyPcyA变体分子积累181，182-DHBV并将其提供给源自A的CBCR分子。码头值得注意的是，Val 225被异亮氨酸取代在Acaryochloris属中是特别保守的。总的来说，我们建议，Acaryochloris属之间的PcyA的特定进化可能与叶绿素的收购。d合成能力和生长在长波长远红光环境。
Phycocyanobilin, the primary pigment of both light perception and light-harvesting in cyanobacteria, is synthesized from biliverdin IXα (BV) through intermediate 181, 182-dihydrobiliverdin (181, 182-DHBV) by a phycocyanobilin:ferredoxin oxidoreductase (PcyA). In our previous study, we discovered two PcyA homologs (AmPcyAc and AmPcyAp) derived from Acaryochloris marina MBIC 11017 (A. marina) that exceptionally uses chlorophyll d as the primary photosynthetic pigment, absorbing longer wavelength far-red light than chlorophyll a, the photosynthetic pigment found in most cyanobacteria. Biochemical characterization of the two PcyA homologs identified functional diversification of these two enzymes: AmPcyAc provides 181, 182-DHBV, and PCB to the cyanobacteriochrome (CBCR) photoreceptors, whereas, AmPcyAp specifically provides PCB to the light-harvesting phycobilisome subunit. In this study, we focused on the residues necessary for 181, 182-DHBV supply to the CBCR photoreceptors by AmPcyAc. Based on the SyPcyA structure, we concentrated on the 30 residues that constitute the substrate-binding pocket. Among them, we discovered that Leu151 and Val225 in AmPcyAc were both substituted with isoleucine. During the enzymatic reaction, the SyPcyA variant molecule, possessing V225I and L151I replacements, accumulates the 181, 182-DHBV and supplies it to a CBCR molecule derived from A. marina. It is worth noting that the substitution of Val225 with isoleucine was specifically conserved among the Acaryochloris genus. Collectively, we propose that the specific evolution of PcyA among the Acaryochloris genus may correlate with the acquisition of Chl. d synthetic ability and growth in long-wavelength far-red light environments.
蓝藻藻蓝蛋白：铁氧还蛋白氧化还原酶（PcyA）通过线性四吡咯自由基中间体进行胆绿素还原。
影响因子：
15
作者：
Tu,Shih-Long;Gunn,Alexander;Toney,MichaelD;Britt,RDavid;Lagarias,JClark
通讯作者：
Lagarias,JClark