Oguchi Taichi, Sage-Ono Kimiyo, Kamada Hiroshi, Ono Michiyuki
Gene Research Center, Institute of Biological Sciences, University of Tsukuba, 1-1-1 Ten-nohdai, Tsukuba, Ibaraki 305-8572, Japan.
Gene. 2004 Apr 14;330:29-37. doi: 10.1016/j.gene.2003.11.012.
We isolated and characterized AtC401, a novel Arabidopsis clock-controlled gene that encodes a protein containing the pentatricopeptide repeat (PPR) motif. AtC401 was isolated as an Arabidopsis homolog of Pharbitis nil C401 (PnC401), a gene that encodes a leaf protein closely related to the photoperiodic induction of flowering and displays a circadian rhythm at the transcriptional level. The AtC401 gene spans 5.6 kb and contains 12 exons. Comparisons of the sequences and genomic organization of AtC401 and PnC401 revealed that each has two exons near the 3'-end, which encode a highly conserved domain consisting of 12 repeats of the PPR motif. Phylogenetic analysis of at least 450 Arabidopsis proteins containing PPR motifs revealed that AtC401 and related proteins form a distinct group. Moreover, the position of the intron between the two exons that encode the PPR domain has been conserved exactly in other C401-like genes. Using a reporter assay, we found a fragment (-174 to +73) of AtC401 that was sufficient to regulate circadian rhythmic expression. These results suggest that the conserved domain of AtC401 has a function similar to that of PnC401, and that the expression of C401 genes according to a circadian rhythm is important for protein function.
我们分离并鉴定了AtC401，它是拟南芥中一个新的生物钟调控基因，编码一种含有五肽重复序列（PPR）基序的蛋白质。AtC401是作为牵牛C401（PnC401）的拟南芥同源物被分离出来的，PnC401基因编码一种与开花的光周期诱导密切相关的叶片蛋白，并且在转录水平上呈现昼夜节律。AtC401基因跨度为5.6 kb，包含12个外显子。对AtC401和PnC401的序列及基因组结构进行比较发现，它们在3'端附近各有两个外显子，这两个外显子编码一个由12个PPR基序重复组成的高度保守结构域。对至少450个含有PPR基序的拟南芥蛋白进行系统发育分析表明，AtC401及相关蛋白形成一个独特的群体。此外，在编码PPR结构域的两个外显子之间的内含子位置在其他类似C401的基因中也完全保守。通过报告基因检测，我们发现AtC401的一个片段（-174至+73）足以调控昼夜节律表达。这些结果表明，AtC401的保守结构域具有与PnC401类似的功能，并且C401基因按照昼夜节律表达对蛋白质功能很重要。
