Characterization of Chlamydomonas mutants defective in the H subunit of Mg-chelatase
Characterization of Chlamydomonas mutants defective in the H subunit of Mg-chelatase
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DOI：
10.1007/s004380100574
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发表时间：
2001-11-01
影响因子：
3.1
通讯作者：
Beck, CF
中科院分区：
文献类型：
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作者：
Chekounova, E;Voronetskaya, V;Beck, CF
莱茵衣藻的两种叶绿素缺陷突变体 chl1 和 brs-1 对光敏感，当在黑暗中异养生长时，会积累原卟啉 IX 并表现出黄色/橙色色素沉着。两种突变体中的损伤均被定位到异三聚体镁螯合酶质体定位的 H 亚基基因 (CHLH)，该酶催化镁插入原卟啉 IX。突变体中的遗传缺陷可归因于 CHLH 基因的外显子 9 (chl1) 和外显子 10 (brs-1) 中的 +1 移码突变。在两种突变体中，镁螯合酶的 H 亚基均检测不到，但如 Chl I 所示，与野生型相比，I 和 D 亚基的稳态水平没有改变。 CHLH基因表现出显着的光诱导性：当培养物从黑暗转移到光亮时，mRNA和蛋白质产物的水平都急剧增加，这表明该蛋白质可能在叶绿素生物合成的光调节中发挥关键作用。
Two chlorophyll-deficient mutants of Chlamydomonas reinhardtii, chl1 and brs-1, are light sensitive and, when grown heterotrophically in the dark, accumulate protoporphyrin IX and exhibit yellow/orange pigmentation. The lesions in both mutants were mapped to the gene (CHLH) for the plastid-localized H subunit of the heterotrimeric magnesium chelatase that catalyzes the insertion of magnesium into protoporphyrin IX. The genetic defects in the mutants could be assigned to +1 frameshift mutations in exon 9 (chl1) and exon 10 (brs-1) of the CHLH gene. In both mutants, the H subunit of magnesium chelatase was undetectable, but, as shown for chl I, the steady-state levels of the I and D subunits were unaltered in comparison to wild type. The CHLH gene exhibits marked light inducibility: levels of both the mRNA and the protein product are strongly increased when cultures are shifted from from the dark into the light, suggesting that this protein may play a crucial role in the light regulation of chlorophyll biosynthesis.