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. 2001 Sep;45(9):2609–2615. doi: 10.1128/AAC.45.9.2609-2615.2001

TABLE 4.

Pairwise amino acid and nucleotide sequence analysis of FrxA proteins from 11 pairs of metronidazole-sensitive and -resistant H. pylori isolates

H. pylori strain MIC (μg/ml) Genetic alterationsa in:
Amino acid sequenceb Nucleotide sequencec
5413 8 R at position 206 to H Missense mutation (G to A at position 617)d
6102 8 W at position 137 to R; E at position 164 to G Missense mutations (T to A at position 409; A to G at position 491)d
1838 32 Generated a stop codon at position 46 Frameshift due to one nucleotide (G) deletion at position 46
6413 32 C at position 161 to Y Missense mutation (G to A at position 482)
1950 64 Generated a stop codon at position 74 Frameshift due to one nucleotide (G) deletion at position 208
2312 64 W at position 49 to stop codon Nonsense mutation (G to A at position 146)
2228 128 Generated a stop codon at position 74 Frameshift due to one nucleotide (G) deletion at position 208
1740 128 Generated a stop codon at position 74 Frameshift due to one nucleotide (G) deletion at position 208
1857 128 Q at position 168 to stop codon Nonsense mutation (C to T at position 505)
5078 128 Generated stop codons at positions 22 and 126 Frameshift due to one nucleotide (A) addition at position 55 and one nucleotide (A) deletion at position 316
8076 128 Generated a stop codon at position 74 Frameshift due to one nucleotide (G) deletion at position 208
a

Pairwise amino acid and nucleotide sequence alignment was performed against the metronidazole-sensitive partner strain from the same patient who failed anti-H. pylori therapy containing metronidazole. If the FrxA proteins from metronidazole-resistant strains were not truncated, the amino acid sequences were aligned not only with the partner metronidazole-sensitive strain but also with all other metronidazole-sensitive FrxA amino acid sequences, including H. pylori ATCC 700392 (26) and H. pylori J99 (1). 

b

The initiation amino acid (methionine) was counted as +1. 

c

Nucleotide A from the first codon (ATG) for FrxA was counted as +1. 

d

The shown missense mutations were not found at the indicated positions in FrxA proteins from the 11 paired pretreatment metronidazole-sensitive H. pylori strains, H. pylori ATCC 700392 (26), or J99 (1).