Sequence analysis and activity determination of narU and narZ promoter genes of Salmonella Typhimurium.

M.F. TORREZ LAMBERTI; M.F. BALLESTEROS; M. DE LAS M. PESCARETTI; DELGADO MA

San Luis

Congreso; Congreso Argentino de Microbiologia General-SAMIGE.; 2018

Asociación Civil de Microbiología General

Salmonella Typhimurium and Escherichia coli cells have three nitrate reductases (Nap, NR-A and NR-Z) involved in adaptation to growth on anaerobic and/or on oxidized carbon environment. Previously, wedemonstrated that RcsB and RstA regulators control the narZ gene expression, involved in the synthesis of NR-Z, in a carbon source-dependent pathway. Since the regulatory region that controls the narZexpression is not well defined and the data is controversial, here we investigate which is the promoter whose activity allows the transcription of narZ. In Salmonella, some reports postulated that narU gene isupstream of narZ and it is the first gene of the operon, while others argue that they are independently transcribed. We localized the transcription start site, the -10 and -35 boxes in both promoters, bybioinformatics analysis. Then, these regulatory region were cloned into the plasmid pFU62, harboring the β-galactosidase encoding gene as reporter of the activity of each promoter. The effect of the RcsBoverproduction was also analyzed and compared with data obtained from chromosomal narZ::lacZ transcriptional fusion to define it narZ promoter sequence and to determine the impact of this regulator in thegene expression.