Department of Biotechnology, Jožef Stefan Institute, Jamova cesta 39, SI1000 Ljubljana, Slovenia.
Plant Physiol Biochem. 2013 Jan;62:79-87. doi: 10.1016/j.plaphy.2012.10.022. Epub 2012 Nov 13.
Protein breakdown by proteases is basic to the plant response to abiotic stresses such as drought. A large number of genes encoding proteases or putative proteases exist in plants. Only a few of those involved in the response to drought have been characterized, and their regulation is poorly understood. We have identified two new subtilases from leaves of Phaseolus vulgaris L. cultivar Zorin, PvSLP1 and PvSLP2. PvSLP1 was identified at the gene level, using primers based on the gene sequence of the putative drought induced serine protease from Arachis hypogaea L. In P. vulgaris, expression of the PvSLP1 transcript did not change on water withdrawal. PvSLP2 was isolated and characterized at the protein level, together with complete gene and cDNA sequences. The deduced amino acid sequences of both PvSLP1 and PvSLP2 are characteristic of plant subtilases of the S8 family of clan SB. PvSLP2 shows 33% sequence identity to PvSLP1. Expression of the PvSLP2 transcript did not change on withdrawal of water, but its proteolytic activity in leaves increased, depending on the age and position of the leaf. In addition, the level of activity in senescent leaves of well watered plants was higher than in mature or young leaves. These results, together with the fact that PvSLP2 cleaves peptide bonds following an Arg residue, point to regulation of PvSLP2 subtilase activity at translational and/or post-translational levels and suggest a specific role in the response to drought and senescence.
蛋白酶介导的蛋白质水解是植物响应非生物胁迫（如干旱）的基础。植物中存在大量编码蛋白酶或假定蛋白酶的基因。尽管已经鉴定出一些参与干旱响应的基因，但对其调控机制仍知之甚少。我们从普通菜豆（Phaseolus vulgaris L.）品种 Zorin 的叶片中鉴定出两种新的枯草杆菌蛋白酶 PvSLP1 和 PvSLP2。使用基于落花生中假定干旱诱导丝氨酸蛋白酶基因序列设计的引物，在基因水平上鉴定出 PvSLP1。在普通菜豆中，PvSLP1 转录物的表达在水分胁迫时没有变化。PvSLP2 是在蛋白质水平上分离和鉴定的，同时还获得了完整的基因和 cDNA 序列。PvSLP1 和 PvSLP2 的推导氨基酸序列均具有家族 SB 的 S8 蛋白酶的植物枯草杆菌蛋白酶特征。PvSLP2 与 PvSLP1 具有 33%的序列同一性。水分胁迫时 PvSLP2 转录物的表达没有变化，但叶片中的蛋白水解活性增加，这取决于叶片的年龄和位置。此外，水分充足的植物衰老叶片中的活性水平高于成熟或幼嫩叶片。这些结果，加上 PvSLP2 切割 Arg 残基后的肽键的事实，表明 PvSLP2 枯草杆菌蛋白酶活性在翻译和/或翻译后水平受到调控，并提示其在干旱和衰老响应中具有特定作用。
