Behavior of Bradyrhizobium SEMIA6144 membrane during adaptation to water deficit.

CESARI ADRIANA; REGUERA Y.B.; PAULUCCI N.S.; PAULUCCI N.S., GONZÁLEZ ANTA G., GALLARATO L.A., VICARIO J.C., CESARI A.B., KILMURRAY C., GARCÍA M.B., DARDANELLI M.S.

Córdoba

Congreso; SAIB; 2016

MI-P06BEHAVIOR OF Bradyrhizobium SEMIA6144 MEMBRANE DURING ADAPTATION TO WATER DEFICITCesari AB, Reguera YB, Paulucci NS, Kilmurray C, Dardanelli MS.Conicet y Departamento de Biología Molecular, FCEFQyN, UNRC. Río Cuarto, Córdoba, Argentina.E-mail: acesari@exa.unrc.edu.arThe membrane lipid bilayer is one of the primary cellular targets affected by variations in medium osmolarity, which cause changes in fluidity that may exert negative effects. We evaluate the behavior of the membrane ofBradyrhizobiumSEMIA6144 during adaptation to polyethylene glycol (PEG). B. SEMIA6144 was exposed to growth and PEG shock. A fluidizing effect on the membrane was observed 10 min after shock; however, the bacteria were able to restore optimal fluidity. This rapid response (1 h) was mediated by an increase in lysophosphatidylethanolamine from phosphatidylethanolamine and an increase in saturated fatty acids, resulting in greater membrane rigidity. When the cells were exposed to shock for 5 h and 24 h, the amount of lysophosphatidylethanolamine decreased while phosphatidylethanolamine increased. This phospholipid turnover was associated with elevated phospholipase A activity after 1 h of shock. Membrane fluidity of cells grown with PEG was also equal to that of the control; however, the response was an increase in phosphatidylcholine at the expense of phosphatidylethanolamine, and an increase in levels of unsaturated fatty acids.We conclude that during PEG shock, the membrane composition of B. SEMIA6144 is rapidly remodeled to counter fluidizing effect; then, this response is dynamically modified by process that involves phospholipid and acyl chain turnover.MI-P07