Disease relevance of ksgA

• The ksgA gene of Escherichia coli encodes a methyltransferase (MeT) that specifically dimethylates two adjacent adenosines near the 3' end of 16S RNA in the 30S particle [1].
• ExpR, a LuxR homolog of Erwinia carotovora subsp. carotovora, activates transcription of rsmA, which specifies a global regulatory RNA-binding protein [2].
• To investigate the role of RsmA in Proteus mirabilis, the rsmA gene from Proteus mirabilis (hereafter referred to as rsmA(Pm)) was cloned [3].

High impact information on ksgA

• The were not sensitive to kasugamycin, the apaH- apaG- ksgA- strain filamented and stopped growing in the presence of this antibiotic at 600 micrograms/ml [4].
• Moreover, the expression of the rsmA-lacZ fusion in Escherichia coli is much higher in the presence of expR(71) (the expR gene of E. carotovora subsp. carotovora strain Ecc71) than in its absence [2].
• These observations strongly suggest transcriptional activation of rsmA resulting from a direct and specific interaction between ExpR(71) and the rsmA promoter [2].
• Several lines of evidence establish that N-3-oxohexanoyl-L-homoserine lactone (3-oxo-C6-HL), the major AHL analog produced by E. carotovora subsp. carotovora strain Ecc71, inhibits ExpR(71)-mediated activation of rsmA expression [2].
• We also show that purified preparation of MBP-ExpR(71) binds (MBP, maltose binding protein) rsmA DNA [2].

Chemical compound and disease context of ksgA

• Various plasmids that contain the Escherichia coli ksgA gene, which encodes a 16S rRNA adenosine dimethyltransferase (methylase), were constructed [5].
• Among eight suppressors isolated, six were located at 1 min of the E. coli genomic map, and the gene responsible for the suppression of Era(Cs) (E200K) was identified as the ksgA gene for 16S rRNA transmethylase, whose mutation causes a phenotype of resistance to kasugamycin, a translation initiation inhibitor [6].

Biological context of ksgA

• Previously, Blanchin-Roland et al. showed that ksgA and apaH form a complex operon (Mol. Gen. Genet. 205:515-522, 1986) [7].
• Several plasmids were constructed with inserts which complemented chromosomal ksgA mutations [1].
• Nucleotide sequence of the ksgA gene of Escherichia coli: comparison of methyltransferases effecting dimethylation of adenosine in ribosomal RNA [1].
• In the plasmid pUC8ksgA7, the coding region of the ksgA gene is preceded by the lac promoter (Plac) and a small open reading frame (ORF) [8].
• The reading frame begins with the ATG initiation codon of lacZ and ends a few nucleotides beyond the ATG start codon of ksgA [8].

Anatomical context of ksgA

• The mutant ribosomes could also be methylated by the ksgA methyltransferase to 70-120% of the expected amount [9].
• A low-copy plasmid carrying rsmA of E. carotovora subsp. carotovora strain 71 caused suppression of antibiotic production in E. carotovora subsp. betavasculorum, flagellum formation in E. carotovora subsp. carotovora, carotenoid production in E. herbicola and E. stewartii, and indigoidine production in E. chrysanthemi [10].

Associations of ksgA with chemical compounds

• We have compared the amino acid (aa) sequence of the ksgA-encoded enzyme with three published sequences of MeT involved in dimethylation of an adenosine residue in 23S RNA and rendering the organisms resistant to the MLS antibiotics [1].
• In E. amylovora, rsmA of E. carotovora subsp. carotovora suppressed the elicitation of the hypersensitive reaction in tobacco leaves and the production of disease symptoms in apple shoots, in addition to repressing motility and extracellular polysaccharide production [10].

Other interactions of ksgA

• In one of these plasmids, the DNA encoding the N-terminal part of the methylase was fused to the lacZ gene, and in another construct, the ksgA gene contained a deletion which resulted in a truncated version of the methylase [5].
• In N. gonorrhoeae, the genes trpB and ksgA were found immediately downstream of iga [11].

Analytical, diagnostic and therapeutic context of ksgA

• Northern blot data presented here demonstrate that rsmA and rsmA-like genes are also expressed in soft-rotting and non-soft-rotting Erwinia spp. such as E. amylovora, E. carotovora subsp. atroseptica, E. carotovora subsp. betavasculorum, E. carotovora subsp. carotovora, E. chrysanthemi, E. herbicola and E. stewartii [10].

References