ALTERED MONOVINYL AND DIVINYL PROTOCHLOROPHYLLIDE POOLS IN BCHJ MUTANTS OF RHODOBACTER-CAPSULATUS - POSSIBLE MONOVINYL SUBSTRATE DISCRIMINATION OF LIGHT-INDEPENDENT PROTOCHLOROPHYLLIDE REDUCTASE
ALTERED MONOVINYL AND DIVINYL PROTOCHLOROPHYLLIDE POOLS IN BCHJ MUTANTS OF RHODOBACTER-CAPSULATUS - POSSIBLE MONOVINYL SUBSTRATE DISCRIMINATION OF LIGHT-INDEPENDENT PROTOCHLOROPHYLLIDE REDUCTASE
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DOI：
10.1074/jbc.270.8.3732
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发表时间：
1995-02-24
影响因子：
4.8
通讯作者：
BAUER, CE
中科院分区：
文献类型：
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作者：
SUZUKI, JY;BAUER, CE
特别是在陆地植物中，已经确定叶绿素中间体、Mg-原卟啉、Mg-原卟啉单甲酯、原叶绿素和叶绿素以单乙烯基和二乙烯基形式存在。单乙烯基和二乙烯基中间体的库根据物种、组织年龄和光照状况而不同。我们研究了紫色非硫光合真细菌Rhodobacter capsulatus中原叶绿酸和叶绿酸的单乙烯基和二乙烯基特性。我们的研究结果表明，已知完全阻断原叶绿素还原为叶绿素的基因突变（如bchN、bchB和bchL突变体）积累了一个单乙烯基和二乙烯基形式的原叶绿素库，就像在植物中观察到的那样。然而，我们还观察到，位于光合作用基因簇中的基因bchJ中的定向插入和缺失突变，影响单乙烯基和二乙烯基原叶绿素的比例。具体地，bchJ破坏的菌株积累降低水平的细菌叶绿素，伴随着二乙烯基原叶绿素的积累。bchJ的突变体与bchL中的第二突变组合仍然产生单乙烯基和二乙烯基原叶绿素的混合池;然而，单乙烯基与二乙烯基原叶绿酸的比例偏向于二乙烯基原叶绿酸。因此，这些结果确定bchJ作为第一个测序的基因，影响在任何光合生物的色素中间体的二乙烯基到单乙烯基的比例，此外，我们的研究结果还表明，光依赖性原叶绿素还原酶是歧视的单乙烯基基板。
In land plants in particular, it has been well established that chlorophyll intermediates, Mg-protoporphyrin, Mg-protoporphyrin monomethylester, protochlorophyllide, and chlorophyllide occur as monovinyl and divinyl forms, The pool of monovinyl and divinyl intermediates differ according to species, age of tissue, and light regime, In this study, we investigated the monovinyl and divinyl characteristics of protochlorophyllide and chlorophyllide in the purple non-sulfur photosynthetic eubacterium Rhodobacter capsulatus. Our results indicate that mutations in genes known to completely block the reduction of protochlorophyllide to chlorophyllide (such as bchN, bchB, and bchL mutants), accumulate a pool of monovinyl and divinyl forms of protochlorophyllide just as observed in plants, However, we also observed that directed insertion and deletion mutations in bchJ, a gene located in the photosynthesis gene cluster, affected the ratio of monovinyl and divinyl protochlorophyllide, Specifically, bchJ-disrupted strains accumulate reduced levels of bacteriochlorophyll concomitant with the accumulation of divinyl protochlorophyllide, Mutants of bchJ in combination with a second mutation in bchL still produce a mixed pool of monovinyl and divinyl protochlorophyllide; however, the ratio of monovinyl to divinyl protochlorophyllide is skewed in favor of divinyl protochlorophyllide. These results thus identify bchJ as the first sequenced gene that affects the divinyl to monovinyl ratio of photopigment intermediates in any photosynthetic organism, In addition, the results of our study also suggest that light-independent protochlorophyllide reductase is discriminatory for a monovinyl substrate.