Role of the extracitoplasmic (ECF) sigma factors in Rhizobium etli

In this line we are interested in knowing the role of the ECF sigma factors, subunits of the RNA polymerase that recognize specific promotors of genes to be transcribed (sigmulon). The ECF factors are involved in envelope stress response, for example, a member of this group regulates the iron uptake, oxidative and heat shock in E. coli, alginate production and cyst formation in A. vinelandii, exotoxin production and oxidative stress in P.aeruginosa, etc. In R. etli there are about 18 ECF-factors and their role is unknown, therefore we are studying their role in the legume-bacteria interaction process , in different stresses (like oxidative, osmotic, heat shock) and in free-living conditions. In order to do that, we are determining the conditions that allow the gene expression for each ECF sigma factor as well as constructing mutants that will allow us to evaluate their biological function.