Disease relevance of sulA

• In E. coli PQ37, a test organism used for the assessment of genotoxicity, lacZ, the beta-galactosidase gene is placed under the control of sfiA, one of the SOS genes through an operon fusion [1].
• To measure sfiA expression in the different strains, we first constructed a lambda transducing phage carrying an sfiA::lac operon fusion [2].
• Hydroxyurea at concentrations higher than 10(-2) M induced the recA and sfiA genes of E. coli as well as the lambda prophage by a pathway independent of the recBC genes [3].

High impact information on sulA

• The work reported here establishes the existence of the latter type of replication-division coupling in E. coli, and shows that the sfiA gene product is an inducible component of this division inhibition mechanism which is synthesized at high levels after perturbations of DNA replication [4].
• The influence of the growth delay induced by near u.v. radiation on the SOS response was monitored by comparing the level of sfiA expression by means of a sfiA::lacZ fusion in both a nuvA+ cell and an isogenic nuvA mutant [5].
• The kinetics of sfiA induction in near u.v.-illuminated nuvA+ cells, whether treated with 254 nm light or not, is unusual and follows the growth curve: only after 50 min is sfiA derepression observed [5].
• The sfiA operon was turned on at a 10-fold lower concentration of methylmethane sulfonate or dimethyl sulfate in tagA strains, lacking specific 3-methyladenine-DNA glycosylase, than in wild-type strains [6].
• 3-Methyladenine residues in DNA induce the SOS function sfiA in Escherichia coli [6].

Chemical compound and disease context of sulA

• Lastly, cis-DDP caused marked expression of a sulA fusion mutant while not inducing any of the other E. coli fusion mutants [7].
• SOS induction levels were measured by beta-galactosidase assays in cisplatin-treated and untreated E. coli PQ30 that has the lacZ gene fused to the sfiA promoter [8].
• Plasmid R6-5 contains a locus whose product inhibits induction of sfiA and prophage lambda in a recA441 mutant at 42 degrees C and in a recA+ host after treatment with nalidixic acid [9].
• The supernatants from probiotic and furazolidone co-incubation exhibited rather strong suppression on SOS induction produced by furazolidone on E. coli PQ 37 (sfiA: lacZ) [10].
• Increasing doses of alkylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine, diethyl sulphate and ethylmethane sulphonate cause an inhibition of the expression of the recA and sfiA genes of wild-type Escherichia coli [11].

Biological context of sulA

• Compared with the aidB gene, a component of the SOS system, the sulA (sfiA) gene, responded to changes in cytoplasmic pH and in the level of intracellular thiols in an opposite way [12].
• The filamentation of ruv strains is abolished by mutations in sfiA or sfiB that prevent SOS induced inhibition of cell division, but this does not restore resistance to UV radiation [13].
• Many recombination, DNA repair and DNA replication mutants have high basal levels of SOS expression as determined by a sulAp-lacZ reporter gene system on a population of cells [14].
• To distinguish between these two models, a method to quantify SOS expression in individual bacterial cells was developed by fusing an SOS promoter (sulAp) to the green fluorescent protein (gfp) reporter gene and inserting it at attlambda on the Escherichia coli chromosome [14].
• Mutations in these genes also cause decreases in cell viability and alterations in UV-inducible sulAp-lacZ (SOS) expression [15].

Associations of sulA with chemical compounds

• Treatment with the known carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) revealed that the promoter for the ColD plasmid-borne cda gene had responses 12, 5, and 3 times greater than the recA, sulA, and umuDC promoters, respectively, and also considerably higher sensitivity [16].
• On the other hand, cyclic AMP does not affect the uv-mediated induction of the recA, sfiA, and umuDC genes [17].
• Pretreatment with ferricyanide inhibited H2O2-induced expression of the sfiA gene which is the member of the gene family controlled by the recA and lexA genes [18].
• The results obtained show that expression of the recA and sfiA genes was inhibited neither in the UV-irradiated nrdA mutant at 42 degrees C nor in the wild-type strain in the presence of hydroxyurea [19].
• The induction of recA, umuC and sfiA genes by quercetin was studied in the presence and in the absence of S9 mix [20].

Regulatory relationships of sulA

• The recA and sfiA genes of Escherichia coli are SOS operons regulated negatively by the LexA repressor [21].
• The umuC gene fusion was induced at lower concentrations of 4-quinolone than was the sfiA gene fusion [22].
• The kinetics of the recA, sfiA and umuDC genes transcription were studied during a double SOS-inducing treatment in Escherichia coli cells using several strains carrying lacZ gene fusions [23].

Other interactions of sulA

• In Escherichia coli, the cell division block observed during the SOS response requires the product of the sfiA gene, whose expression is regulated negatively by the LexA repressor and positively by the RecA protease [2].
• The infA3 mutation, which suppresses tif-mediated filamentation, reduced induction of sfiA expression in a tif infA3 strain at 42 degrees C or after UV irradiation [2].
• We found that the initial steady rate of sfiA expression was proportional to the UV dose and was identical in uvr+ and uvrA backgrounds [24].
• The induction of sfiA gene is decreased by the presence of S9 mix, whereas an opposite effect was observed concerning umuC and recA [20].
• After exposure to H2O2, mutagenesis and filamentation also occurred with the dose response characteristic of SOS induction and mode one killing, but these responses were not dependent on the lexA-regulated umuC mutagenesis or sfiA filamentation functions, respectively [25].

Analytical, diagnostic and therapeutic context of sulA

• Construction of a ColD cda promoter-based SOS-green fluorescent protein whole-cell biosensor with higher sensitivity toward genotoxic compounds than constructs based on recA, umuDC, or sulA promoters [16].
• The positioning of constrictions in Escherichia coli filaments pinching off anucleate cells was analyzed by fluorescence microscopy of dnaX(Ts), dnaX(Ts) sfiA, dnaA46(Ts), gyrA(Am) supF(Ts), and gyrB(Ts) mutants [26].

References