Relle M, Wild A
Institut für Allgemeine Botanik der Johannes Gutenberg-Universität Mainz, Germany.
Plant Mol Biol. 1996 Dec;32(5):923-36. doi: 10.1007/BF00020489.
Phosphoenolpyruvate carboxylase (PEPC) genes and cDNA sequences have so far been isolated from a broad range of angiosperm but not from gymnosperm species. We constructed a cDNA library from seedlings of Norway spruce (Picea abies) and identified cDNAs coding for PEPC. A full-length PEPC cDNA was sequenced. It consists of 3522 nucleotides and has an open reading frame (ORF) that encodes a polypeptide (963 amino acids) with a molecular mass of 109551. The deduced amino acid sequence revealed a higher similarity to the C3-form PEPC of angiosperm species (86-88%) than to the CAM and C4 forms (76-84%). The putative motif (Lys/Arg-X-X-Ser) for serine kinase, which is conserved in all angiosperm PEPCs analysed so far, is also present in this gymnosperm sequence. Southern blot analysis of spruce genomic DNA under low-stringency conditions using the PEPC cDNA as a hybridization probe showed a complex hybridization pattern, indicating the presence of additional PEPC-related sequences in the genome of the spruce. In contrast, the probe hybridized to only a few bands under high-stringency conditions. Whereas this PEPC gene is highly expressed in roots of seedlings, a low-level expression can be detected in cotyledons and adult needles. A molecular phyiogeny of plant PEPC including the spruce PEPC sequence revealed that the spruce PEPC sequence is clustered with monocot and dicot C3- form PEPCs including the only dicot C4 form characterized so far.
到目前为止，磷酸烯醇式丙酮酸羧化酶（PEPC）基因和cDNA序列已从多种被子植物中分离出来，但尚未从裸子植物中分离出来。我们构建了挪威云杉（Picea abies）幼苗的cDNA文库，并鉴定了编码PEPC的cDNA。对一个全长PEPC cDNA进行了测序。它由3522个核苷酸组成，具有一个开放阅读框（ORF），该阅读框编码一个分子量为109551的多肽（963个氨基酸）。推导的氨基酸序列显示，与被子植物的C3型PEPC的相似性更高（86 - 88%），而与景天酸代谢（CAM）和C4型的相似性为76 - 84%。丝氨酸激酶的假定基序（赖氨酸/精氨酸 - X - X - 丝氨酸）在迄今为止分析的所有被子植物PEPC中都是保守的，在这个裸子植物序列中也存在。在低严谨条件下，以PEPC cDNA作为杂交探针，对云杉基因组DNA进行Southern印迹分析，显示出复杂的杂交模式，表明云杉基因组中存在其他与PEPC相关的序列。相反，在高严谨条件下，该探针只与少数条带杂交。虽然这个PEPC基因在幼苗根中高度表达，但在子叶和成年针叶中可检测到低水平表达。包括云杉PEPC序列在内的植物PEPC的分子系统发育分析表明，云杉PEPC序列与单子叶和双子叶C3型PEPC聚集在一起，其中包括迄今为止唯一已鉴定的双子叶C4型。
