title: The Bacillus subtilis desaturase: a model to understand phospholipid modification and temperature sensing.
abstract: Most fatty acid desaturases are members of a large superfamily of integral membrane, O2-dependent, iron-containing enzymes that insert double bonds into previously synthesized fatty acyl chains. The cold shock-induced, membrane-bound desaturase from Bacillus subtilis (Delta5-Des) uses existing phospholipids as substrates to introduce a cis-double bond at the fifth position of the fatty acyl chain. While essentially no three-dimensional structural information is available for these difficult-to-purify enzymes, experimental analysis of the topology of Delta5-Des has provided a model that might be extended to most acyl-lipid desaturases. In addition, studies of the cold-induced expression of Delta5-Des led to the identification of a two-component system composed of a membrane-associated kinase, DesK, and a transcriptional regulator, DesR, which stringently controls the transcription of the des gene, coding for the desaturase. A model for sensing and transduction of low-temperature signals has emerged from our results, which we discuss in the context of transcriptional regulation of membrane lipid fluidity homeostasis.
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario, Suipacha 531, S2002LRK, Rosario, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Mansilla
authors.forename: Diego
authors.initials: D
authors.lastname: de Mendoza
mesh_terms: D000222:Adaptation, Physiological; D001412:Bacillus subtilis / Q000201:enzymology*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D013696:Temperature
chemical_list: D010743:Phospholipids; D044943:Fatty Acid Desaturases