Ferredoxin Gene Mutation in Iranian Trichomonas vaginalis Isolates

Abstract

Background: Trichomonas vaginalis causes trichomoniasis and metronidazole is its chosen drug for treatment. Ferredoxin has role in electron transport and carbohydrate metabolism and the conversion of an inactive form of metronidazole (CO) to its active form (CPR). Ferredoxin gene mutations reduce gene expression and increase its resistance to metronidazole. In this study, the frequency of ferredoxin gene mutations in clinical isolates of T.vaginalis in Tehran has been studied.

Methods: Forty six clinical T. vaginalis isolates of vaginal secretions and urine sediment were collected from Tehran Province since 2011 till 2012. DNA was extracted and ferredoxin gene was amplified by PCR technique. The ferredoxin gene PCR products were sequenced to determine gene mutations.

Results: In four isolates (8.69%) point mutation at nucleotide position -239 (the translation start codon) of the ferredoxin gene were detected in which adenosine were converted to thymine.

Conclusion: Mutation at nucleotide -239 ferredoxin gene reduces translational regulatory protein's binding affinity which concludes reduction of ferredoxin expression. For this reduction, decrease in activity and decrease in metronidazole drug delivery into the cells occur. Mutations in these four isolates may lead to resistance of them to metronidazole.

Keywords: Ferredoxin gene; Mutation; Trichomonas vaginalis.

Fig. 1

The 1.5% agarose gel electrophoresis. M; 100 bp DNA ladder marker, NC; negative control, PC; positive control, TV; Trichomonas vaginalis ferredoxin gene PCR product

Fig. 2

Comparison of the sequence of nucleotides before the translation start codon of the ferredoxin gene by BLAST sofware. TV is nucleotide sequence of wild type isolate and TV-MT is nucleotide sequence of mutant isolate. It shows change in nucleotide position -239, and box shows start of transcription of the ferredoxin gene. The underlined region (28-bp oligomers) is the translational regulatory protein connection zone (Ref 22)