A Transmembrane Histidine Kinase Functions as a pH Sensor

VAZQUEZ, DANIELA BELÉN; DRUSIN, SALVADOR IVÁN; RUYSSCHAERT, JEAN MARIE; BORTOLOTTI, ANA; INDA, MARIA EUGENIA; MORENO, DIEGO M.; ALMADA, JUAN CRUZ; VILLALBA, JUAN MANUEL; CYBULSKI, LARISA ESTEFANIA

Biomolecules

MDPI Multidisciplinary Digital Publishing Institute

Lugar: Basel; Año: 2020 vol. 10 p. 1 - 11

2218-273X

The two-component system DesK-DesR regulates the synthesis of unsaturated fatty acids inthe soil bacteria Bacillus subtilis. This system is activated at low temperature and maintains membranelipid fluidity upon temperature variations. Here, we found that DesK?the transmembrane histidinekinase?also responds to pH and studied the mechanism of pH sensing. We propose that a helixlinking 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 analpha 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 destabilizationand interruption of signaling. This mechanism inhibits unsaturated fatty acid synthesis and rigidifiesthe membrane when Bacillus grows in acidic conditions.