Identification and characterization of a lipoprotein of sporulation in bacillus subtilis

VERÓNICA DIEZ,; GUSTAVO E. SCHUJMAN; DIEGO DE MENDOZA

Mar del Plata

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigadores en Bioquímica (SAIB); 2007

SAIB

IDENTIFICATION AND CHARACTERIZATION OF A LIPOPROTEIN OF SPORULATION IN BACILLUS SUBTILIS Diez V, Schujman GE, de Mendoza D. IBR - CONICET, Facultad Cs Bioq y Farm, UNR, Suipacha 531, 2000 Rosario, Argentina. E-mail: diez@ibr.com.ar In the absence of nutrients initiates a differentiation process called sporulation. After an asymmetrical division two compartments are created. The larger one, called mother cell, engulfs and nurtures the smaller one, forespore, and eventually lyses to release a dormant environmentally resistant spore.When exposed to nutrients, the spore resumes vegetative growth in a process called germination. To identify hypothetical lipoproteins involved in sporulation, we labelled cultures with tritiated palmitic acid and found a putative lipoprotein expressed under the control of the mother cell specific sigma factor . We demonstrated that the protein detected is GerM, previously reported to be necessary for both spore formation and germination. A version of GerM mutated in its putative lipidation site (GerM*) was not able to incorporate tritiated palmitic acid. A mutant strain expressing showed impaired sporulation efficiency and low dipicolinic acid content in sporulating cells. Addition of germinants to the mutant spores resulted in the triggering of an incomplete germination with a significant deficiency in loss of spore refractility but normal loss of heat resistance. These phenotypes are similar to those of a strain, suggesting that the lipobox site of this lipoprotein is critical for its proper function.