A novel multicopy suppressor of a groEL mutation includes two nested open reading frames transcribed from different promoters.

Abstract

When present on a multicopy plasmid, a newly discovered gene (sugE) mapping to 94 min on the Escherichia coli chromosome, suppresses a groEL mutation and mimics the effects of groE overexpression. A groEL mutant of E.coli, transformed with the Klebsiella pneumoniae nif gene cluster, failed to accumulate nitrogenase components [Govezensky et al. (1991) J. Bacteriol., 173, 6339–6346]. Transformation with sugE reversed the mutant phenotype. In wild type K.pneumoniae, transformation with sugE accelerated the rate of nitrogenase biogenesis after nif derepression. In E.coli, transformation with sugE enabled bacteriophage T4 growth in a groEL mutant. A continuous 178 codon open reading frame (ORF) in sugE encloses another, in‐frame, 105 codon ORF similar to a predicted ORF in Proteus vulgaris. In vivo products of both sugE ORFs were observed in transformants expressing the gene from a T7 promoter. In non‐transformed cells, a typical sigma 70‐dependent promoter found upstream of the larger ORF directs sugE transcription during growth at 30 degrees C. At elevated temperatures or in stationary phase cells, another promoter, found within the coding sequence upstream of the smaller ORF, is activated independently of sigma 32. The results suggest that sugE encodes a chaperonin‐related system whose composition might vary with temperature and growth phase.

DNA Sequence Analysis of Regions SurroundingblaCMY-2from MultipleSalmonellaPlasmid Backbones

“…In C. freundii, blc encodes an outer membrane lipoprotein whereas sugE is hypothesized to be a member of the small multidrug resistance (SMR) family of multidrug efflux systems (8,16,26). Therefore, neither of these genes is thought to be involved in bla CMY-2 regulation (39).…”

Overexpression of the Escherichia coli sugE Gene Confers Resistance to a Narrow Range of Quaternary Ammonium Compounds

“…The sugE gene was initially mapped to the 94-min region of the E. coli chromosome and was shown to phenotypically suppress a groEL mutation, mimicking the effect of groE overexpression when present on a multicopy plasmid (5). As demonstrated by Bishop et al (1), a single gene, rather than the two-gene system proposed by Greener et al (5), proved to be present at this locus.…”

“…However, in spite of extensive efforts in this direction, no drug resistance phenotype for the distant SMR family homologues of the SugE subfamily of proteins from various gram-negative and gram-positive bacteria has been reported (8,11,13). The sugE gene was initially mapped to the 94-min region of the E. coli chromosome and was shown to phenotypically suppress a groEL mutation, mimicking the effect of groE overexpression when present on a multicopy plasmid (5). As demonstrated by Bishop et al (1), a single gene, rather than the two-gene system proposed by Greener et al (5), proved to be present at this locus.…”

sugE: A gene involved in tributyltin (TBT) resistance of Aeromonas molluscorum Av27

“…The E. coli-sugE gene encodes a chaperonin-related system whose composition might vary with temperature and growth phase. In that case, two expression models were proposed for sugE regulation permitting both i) constitutive and ii) stress-induced expression dependent on a still-undefined sigma factor (Greener et al, 1993). In the present study, Av27-sugE was constitutively expressed, and its expression was induced by the stress caused by TBT.…”