Identification and Characterization of Geranylgeraniol Kinase and Geranylgeranyl Phosphate Kinase from the Archaebacterium Sulfolobus acidocaldariu
作者:S.-i. Ohnuma、M. Watanabe、T. Nishino
DOI:10.1093/oxfordjournals.jbchem.a021275
日期:1996.3.1
Geranylgeranyl diphosphate is an important precursor of archaebacterial ether-linked lipids, and it has been thought that all of this compound is “de novo” synthesized by geranylgeranyl diphosphate synthase. We studied the phosphorylation of geranylgeraniol, which seems to be related to the salvage pathway of biosynthesis of archaebacterial ether-linked lipids, in the Archaebacterium Sulfolobus acidocaldarius. Activities of geranylgeraniol kinase and geranylgeranyl phosphate kinase were detected in a cell lysate of S.acidocaldarius. The two enzymes were easily separated by ultracentrifugation. The membrane fraction and the cytosolic fraction contained geranylgeraniol kinase activity and geranylgeranyl phosphate kinase activity, respectively. Geranylgeraniol kinase, which requires divalent cation such as Mg2+, Co2+, and Mn2+ and NTP (ATP, GTP, CTP, UTP), catalyzes monophosphorylation of (all-E)-geranylgeraniol to produce geranylgeranyl phosphate. (all-E)-Farnesol, (all-E)-hexaprenol, and (all-E)-octaprenol were also active as substrates, though they were less effective than (all-E)-geranylgeraniol. However, neither geraniol nor (2E,6E,10Z,14Z,18Z,22Z,26Z,30Z,34Z,38Z)-undecaprenol was active. This enzyme is extremely thermostable and its pH optimal is between 6.5 and 8.5. The Michaelis constants for (all-E)-geranylgeraniol and ATP are 27 nM and 650μM, respectively.
二磷酸二异戊烯基是古细菌醚键脂质的重要前体,人们认为这种化合物是由二磷酸二异戊烯基合成酶从头合成的。我们研究了二异戊烯基的磷酸化,它似乎与古细菌醚键脂质的生物合成中的抢救途径有关。在古细菌硫醇酸杆菌的细胞裂解液中检测到了二异戊烯基激酶和二磷酸二异戊烯基激酶的活性。这两种酶很容易通过超速离心分离。膜部分和细胞质部分分别含有二异戊烯基激酶活性和二磷酸二异戊烯基激酶活性。二异戊烯基激酶需要二价阳离子(如Mg2+、Co2+和Mn2+)和NTP(ATP、GTP、CTP、UTP)催化(all-E)-二异戊烯基的磷酸化,生成二磷酸二异戊烯基。(all-E)-法呢醇、(all-E)-六烯醇和(all-E)-八烯醇也是有效的底物,但它们不如(all-E)-二异戊烯基有效。然而,二异戊烯基和(2E,6E,10Z,14Z,18Z,22Z,26Z,30Z,34Z,38Z