Reeve W G, Tiwari R P, Dilworth M J, Glenn A R
Nitrogen Fixation Research Group, School of Biological and Environmental Sciences, Murdoch University, Australia.
FEMS Microbiol Lett. 1997 Aug 1;153(1):43-9. doi: 10.1111/j.1574-6968.1997.tb10461.x.
A 2.8 kb BamHI DNA fragment adjacent to a BamHI fragment containing actR-actS (a sensor/regulator pair required for low pH tolerance in Rhizobium meliloti WSM419) was cloned and sequenced. A computer predicted protein of 821 amino acids, designated HelO, showed extensive similarity with 'DEAH' motif helicases. Expression of helO was higher at pH 7.0 than pH 5.8 and it did not require the product of the actR gene. Inactivation of helO by insertion of a omega interposon at codon 40 did not affect nodulation, growth or tolerance to low pH, high temperature, osmolarity or elevated levels of copper or zinc.
与包含actR - actS（苜蓿根瘤菌WSM419耐低pH所需的传感器/调节因子对）的BamHI片段相邻的一个2.8 kb BamHI DNA片段被克隆并测序。计算机预测的一个由821个氨基酸组成的蛋白质，命名为HelO，与“DEAH”基序解旋酶显示出广泛的相似性。helO在pH 7.0时的表达高于pH 5.8时，且其表达不需要actR基因的产物。通过在第40位密码子处插入一个ω-插入序列使helO失活，并不影响结瘤、生长或对低pH、高温、渗透压或铜或锌水平升高的耐受性。
