Disease relevance of aadA

• Isolation and characterization of the aadA aminoglycoside-resistance gene from Salmonella choleraesuis [1].
• It is homologous (c. 40% total identity) to streptomycin adenylyltransferase, a 3'(9)-O-nucleotidyltransferase (AAD(3')(9)), which is encoded by the aadA gene in Escherichia coli, Agrobacterium tumefaciens, Klebsiella pneumonia, and Serratia marcescens [1].
• These mutant rps7 leaders were ligated into an aadA expression cassette and transformed into the chloroplast of C. reinhardtii and into E. coli [2].
• aadA confers streptomycin resistance in Borrelia burgdorferi [3].
• The aadA gene of plasmid R100 confers resistance to spectinomycin and streptomycin in Myxococcus xanthus [4].

High impact information on aadA

• A biolistic approach was used to integrate two fusion genes, one encoding aminoglycoside-3-adenyltransferase (aadA) and the first 123 aa of the Ssp DnaE intein (In) and the other encoding 36 C-terminal amino acid residues of the Ssp DnaE intein (Ic) and soluble modified green fluorescent protein (smGFP) into N. tabacum plastids [5].
• Transcription from the conII derivatives in the absence of repression interferes with the phenotypic expression of an adjacent drug-resistance gene, aadA [6].
• Southern hybridization analysis revealed that homologous aadA sequences were also present in other streptomycin-resistant Salmonella species [1].
• A model is presented for the evolution of this region of the plasmid genomes in which the 59- base element functions as an insertional "hot spot" and the possibility that this region is analogous to the aadA/aadB region of the Tn21- like transposon family is considered [7].
• Nucleotide sequence of the AAD(2'') aminoglycoside adenylyltransferase determinant aadB. Evolutionary relationship of this region with those surrounding aadA in R538-1 and dhfrII in R388 [7].

Biological context of aadA

• Comparison of the DNA sequences of Tn7 and plasmid R538-1 indicated that their aadA genes were nearly identical [8].
• A segment of the aadB gene sequence (including the promoter region) was found upstream of the aadA gene in R538-1 and of the dhfrII gene in R388 and the proposed promoters for these genes coincide with the aadB promoter region [7].
• The sul3 gene has been identified in isolates from different sources and serotypes, which also carried a class 1 integron with aadA and dfrA gene cassettes [9].
• The SpR gene of pSa has extensive sequence homology with the aadA gene of the plasmid R538-1 [10].
• The kinds and frequencies of recombination events observed between integrative plasmids with aadA and the M. xanthus chromosome are similar to those observed after the transformation of yeast [4].

Anatomical context of aadA

• Integration of the plastome specific aadA cassette into the nuclear genome accounted for a fraction of the resistant cell lines [11].

Associations of aadA with chemical compounds

• The aadA genes, encoding resistance to streptomycin and spectinomycin, have been found as gene cassettes in different gram-negative and gram-positive bacterial species [12].
• Depending on the presence or absence and level of expression of the genes aacA4, aadA, and dfrI and of insertion element IS15, four types of plasmids could be distinguished [13].
• Selection for aadA in M. xanthus can be carried out independently of, or simultaneously with, selection for resistance to kanamycin [4].

Other interactions of aadA

• Transformation experiments confirmed statistical associations by demonstrating that elt, estB, astA, aadA and sul1 were located with catA1 on a large ETEC plasmid [14].
• PCR was carried out for detection of the streptomycin resistance genes strA-strB and the integron-associated aadA gene cassettes [15].
• Strains harbouring both the strA-strB genes and an aadA gene cassette had higher streptomycin MICs than those harbouring either alone [15].
• The aadA, tetA, and sulI genes were most commonly detected in bacteria resistant to streptomycin, tetracycline and sulfonamide, respectively [16].

Analytical, diagnostic and therapeutic context of aadA

• Plasmids with the aadA gene from plasmid R100, which confers resistance to the aminoglycosides spectinomycin and streptomycin in Escherchia coli, can be introduced into wild-type Myxococcus xanthus, strain DK1622, by electroporation [4].

References