Kabała Katarzyna, Kłobus Grazyna
Department of Plant Physiology, Institute of Plant Biology, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland.
J Plant Physiol. 2008 Nov 28;165(17):1830-7. doi: 10.1016/j.jplph.2008.01.003. Epub 2008 Mar 14.
The time-dependent effect of 50mM NaCl on the activities of two tonoplast proton pumps was investigated in Cucumis sativus L. var. Krak root cells. Distinct activity profiles for vacuolar proton transporting ATPase (V-ATPase) (EC 3.6.3.14) and vacuolar proton transporting pyrophosphatase (V-PPase) (EC 3.6.1.1) under salinity are presented. ATP-dependent proton transport and ATP hydrolysis increased after 24h of NaCl exposure, and then decreased in roots stressed with NaCl for 4 and 8d. Both PP(i)-driven H(+) transport and PP(i) hydrolysis were clearly inhibited by NaCl at all times examined. It was demonstrated that changes in enzyme activities were not due to the salt action on the expression of encoding genes. The levels of specific transcripts for subunit A of V-ATPase (CsVHA-A), subunit c of V-ATPase (CsVHA-c) and V-PPase (CsVP) were similar in cucumber roots untreated (control) and treated with salt. Such results suggest that alterations of proton pump activities under salinity are rather due to the post-translational alterations induced by NaCl.
研究了50mM NaCl对黄瓜（Cucumis sativus L. var. Krak）根细胞中两种液泡膜质子泵活性的时间依赖性影响。给出了盐胁迫下液泡质子转运ATP酶（V-ATPase）（EC 3.6.3.14）和液泡质子转运焦磷酸酶（V-PPase）（EC 3.6.1.1）的不同活性曲线。NaCl处理24小时后，ATP依赖的质子转运和ATP水解增加，然后在NaCl胁迫4天和8天的根中下降。在所有检测时间，PP(i)驱动的H(+)转运和PP(i)水解均被NaCl明显抑制。结果表明，酶活性的变化并非由于盐对编码基因表达的作用。V-ATPase亚基A（CsVHA-A）、V-ATPase亚基c（CsVHA-c）和V-PPase（CsVP）的特定转录本水平在未处理（对照）和盐处理的黄瓜根中相似。这些结果表明，盐胁迫下质子泵活性的改变更可能是由NaCl诱导的翻译后改变所致。
