Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario-Argentine National Research Council-CONICET, Suipacha 531 CP 2000, Argentina.
Departamento de Químico-Física, Facultad de Ciencias Bioquímicas y Farmacéuticas, Área Física, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Santa Fe, Argentina.
Biomolecules. 2020 Aug 14;10(8):1183. doi: 10.3390/biom10081183.
The two-component system DesK-DesR regulates the synthesis of unsaturated fatty acids in the soil bacteria . This system is activated at low temperature and maintains membrane lipid fluidity upon temperature variations. Here, we found that DesK-the transmembrane histidine kinase-also responds to pH and studied the mechanism of pH sensing. We propose that a helix linking the transmembrane region with the cytoplasmic catalytic domain is involved in pH sensing. This helix contains several glutamate, lysine, and arginine residues At neutral pH, the linker forms an alpha helix that is stabilized by hydrogen bonds in the i, i + 4 register and thus favors the kinase state. At low pH, protonation of glutamate residues breaks salt bridges, which results in helix destabilization and interruption of signaling. This mechanism inhibits unsaturated fatty acid synthesis and rigidifies the membrane when grows in acidic conditions.
双组分系统 DesK-DesR 调控土壤细菌中不饱和脂肪酸的合成。该系统在低温下被激活，并在温度变化时维持膜脂的流动性。在这里，我们发现跨膜组氨酸激酶 DesK 也能响应 pH 值，并研究了其 pH 值感应机制。我们提出，连接跨膜区域与细胞质催化结构域的螺旋参与了 pH 值感应。该螺旋包含几个谷氨酸、赖氨酸和精氨酸残基。在中性 pH 值下，接头形成一个α螺旋，在 i，i + 4 位形成氢键，从而有利于激酶状态。在低 pH 值下，谷氨酸残基的质子化会打破盐桥，导致螺旋不稳定，信号中断。这种机制抑制了不饱和脂肪酸的合成，并使细胞膜在酸性条件下生长时变得僵硬。
