Ray M K, Kumar G S, Shivaji S
Centre for Cellular and Molecular Biology, Hyderabad, India.
J Bacteriol. 1994 Jul;176(14):4243-9. doi: 10.1128/jb.176.14.4243-4249.1994.
Phosphorylation of lipopolysaccharide (LPS) from a psychrotrophic bacterium, Pseudomonas syringae, from Antarctica was studied by using sucrose gradient-separated membrane fractions. The bacterium was found to possess an LPS kinase which could phosphorylate more LPS postsynthetically at higher temperatures. The phosphorylation was low at a lower temperature and was also found to occur in vivo. After phosphorylation of LPS in vitro, it was found that the major part of the radioactivity (> 85%) was associated with the core oligosaccharide region of the LPS. The phosphate groups of this region are probably involved in the binding of metal ions, which could be removed by EDTA. The cells grown at the lower temperature probably contained fewer divalent cations because of the smaller amount of phosphate and thereby were more sensitive to EDTA. The cells were also more sensitive to cationic antibiotics at the lower temperature. A possible role of this differential phosphorylation of LPS in modulating the function of the outer membrane as a permeability barrier in the psychrotroph is discussed.
利用蔗糖梯度分离的膜组分，对来自南极洲的嗜冷细菌丁香假单胞菌的脂多糖（LPS）磷酸化进行了研究。发现该细菌拥有一种LPS激酶，在较高温度下能够在合成后使更多的LPS磷酸化。磷酸化在较低温度下较低，并且也发现在体内发生。体外LPS磷酸化后，发现大部分放射性（>85%）与LPS的核心寡糖区域相关。该区域的磷酸基团可能参与金属离子的结合，金属离子可被EDTA去除。在较低温度下生长的细胞可能由于磷酸量较少而含有较少的二价阳离子，因此对EDTA更敏感。在较低温度下，细胞对阳离子抗生素也更敏感。讨论了LPS这种差异磷酸化在调节嗜冷菌外膜作为渗透屏障功能中的可能作用。
