Two S-adenosylmethionine synthetase-encoding genes differentially expressed during adventitious root development in Pinus contorta
Two S-adenosylmethionine synthetase-encoding genes differentially expressed during adventitious root development in Pinus contorta
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DOI：
10.1023/a:1010637012528
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发表时间：
2001-06-01
影响因子：
5.1
通讯作者：
von Arnold, S
中科院分区：
文献类型：
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作者：
Lindroth, AM;Saarikoski, P;von Arnold, S
已在松树中鉴定出两种 S-腺苷甲硫氨酸合成酶 (SAMS) cDNA：PcSAMS1 和 PcSAMS2。我们发现这两个基因在根发育过程中存在差异表达。因此，PcSAMS1优先在根中表达，并在不定根发育开始时在分生组织中表现出特定的表达模式，而PcSAMS2在根和芽中表达，并在不定根形成过程中下调。两个SAMS基因的表达与不定根形成过程中的SAMS活性水平不同。我们得出的结论是，其他有待表征的 SAMS 基因可能有助于观察到的 SAMS 活性，或者 PcSAMS1 和 PcSAMS2 的活性受到转录后调控的影响。 PcSAMS1 和 PcSAMS2 推导的氨基酸序列高度不同，表明其功能不同。然而，两者都携带所有植物 SAMS 共有的两个完全保守的基序。在蛋白质水平上，PcSAMS2与其他分离的真核SAMS有约90%的同一性，而PcSAMS1与其他植物SAMS的同一性不到50%。在系统发育比较中，PcSAMS1 似乎与所有其他 SAMS 基因显着不同。尽管如此，PcSAMS1 能够补充酿酒酵母 sam1 sam2 双突变体，表明它编码功能性 SAMS 酶。
Two S-adenosylmethionine synthetase (SAMS) cDNAs, PcSAMS1 and PcSAMS2, have been identified in Pinus contorta. We found that the two genes are differentially expressed during root development. Thus, PcSAMS1 is preferentially expressed in roots and exhibits a specific expression pattern in the meristem at the onset of adventitious root development, whereas PcSAMS2 is expressed in roots as well as in shoots and is down-regulated during adventitious root formation. The expression of the two SAMS genes is different from the SAMS activity levels during adventitious root formation. We conclude that other SAMS genes that remain to be characterized may contribute to the observed SAMS activity, or that the activities of PcSAMS1 and PcSAMS2 are affected by post-transcriptional regulation. The deduced amino acid sequences of PcSAMS1 and PcSAMS2 are highly divergent, suggesting different functional roles. However, both carry the two perfectly conserved motifs that are common to all plant SAMS. At the protein level, PcSAMS2 shares about 90% identity to other isolated eukaryotic SAMS, while PcSAMS1 shares less than 50% identity with other plant SAMS. In a phylogenetic comparison, PcSAMS1 seems to have diverged significantly from all other SAMS genes. Nevertheless, PcSAMS1 was able to complement a Saccharomyces cerevisiae sam1 sam2 double mutant, indicating that it encodes a functional SAMS enzyme.