Espineda C E, Linford A S, Devine D, Brusslan J A
Department of Biological Sciences, California State University, 1250 Bellflower Boulevard, Long Beach, CA, 90840-3702, USA.
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10507-11. doi: 10.1073/pnas.96.18.10507.
Chlorophyll b is synthesized from chlorophyll a and is found in the light-harvesting complexes of prochlorophytes, green algae, and both nonvascular and vascular plants. We have used conserved motifs from the chlorophyll a oxygenase (CAO) gene from Chlamydomonas reinhardtii to isolate a homologue from Arabidopsis thaliana. This gene, AtCAO, is mutated in both leaky and null chlorina1 alleles, and DNA sequence changes cosegregate with the mutant phenotype. AtCAO mRNA levels are higher in three different mutants that have reduced levels of chlorophyll b, suggesting that plants that do not have sufficient chlorophyll b up-regulate AtCAO gene expression. Additionally, AtCAO mRNA levels decrease in plants that are grown under dim-light conditions. We have also found that the six major Lhcb proteins do not accumulate in the null ch1-3 allele.
叶绿素b由叶绿素a合成，存在于原绿藻、绿藻以及非维管植物和维管植物的捕光复合体中。我们利用莱茵衣藻叶绿素a加氧酶（CAO）基因的保守基序，从拟南芥中分离出一个同源基因。这个基因，即AtCAO，在渗漏型和无效型chlorina1等位基因中均发生突变，并且DNA序列变化与突变表型共分离。在叶绿素b水平降低的三种不同突变体中，AtCAO mRNA水平较高，这表明叶绿素b不足的植物会上调AtCAO基因表达。此外，在弱光条件下生长的植物中，AtCAO mRNA水平会降低。我们还发现，六个主要的Lhcb蛋白在无效的ch1-3等位基因中不积累。
