Toktam POOLAD, Mojtaba TOUSHEH, Manijeh KAHBAZI, Mohammad ARJOMANDZADEGAN, Azam AHMADY, Poorya RAFEE

Study of pyrazinamidase structural changes in pyrazinamide resistant and susceptible isolates of Mycobacterium tuberculosis

Giriş: Pirazinamid, tüberküloz tedavisindeki ilk basamak ilaçlardan biridir. 359 ve 374 pnc genlerinin iki nükleotidindeki mutasyonun, pirazinamid direnciyle yüksek derecede ilişkili olduğu gösterilmiştir. Materyal ve Metod: Bu çalışmada, 30 klinik Mycobacterium tuberculosis izolatında sekans analiziyle bu iki kodondaki mutasyonlar araştırıldı. Pirazinamid dirençli ve duyarlı izolatlarda, mutasyonlu ve mutasyonsuz bu gen tarafından kodlanan protein yapıları araştırıldı. Bulgular: 359 ve 374 pozisyonlarındaki mutasyonun, elektronik yük ve mutasyona uğramış aminoasitlerin aktif enzim durumuna uzaklığı gibi bazı parametreleri değiştirdiği saptandı. Bu durumlarda, pirazinamidazın yapı ve fonksiyonu değişti ve antibiyotik etkisizdi ve sonuçta M. tuberculosis’de pirazinamide dirence neden oldu. Sonuç: Sonuç olarak, bu çalışmada pirazinamide dirençli klinik M. tuberculosis izolatlarında protein değişiklikleri tanımlandı.

Pirazinamid dirençli ve duyarlı Mycobacterium tuberculosis izolatlarında pirazinamidaz yapısal değişikliklerinin çalışması

Introduction: Pyrazinamide is one of the first line four drugs for treatment of tuberculosis. It was proved that mutations in two nucleotides of 359 and 374 pnc genes are highly associated with resistance to pyrazinamide. Matedials and Methods: In this study, mutations in these two codones in 30 clinical isolates of Mycobacterium tuberculo- sis were detected by means of sequencing. Protein structures encoded by this gene with and without mutation were inves- tigated in resistant and susceptible isolates to pyrazinamide, respectively. Results: Mutation in the positions 359 and 374 altered some parameters like change in electronic charge, distance change of mutated amino acids to situation of active enzyme and metal connection situation. In these conditions, structure and function of pyrozinamidase enzyme were changed and antibiotic was ineffective and consequently caused resistance to pyrazinamide in M. tuberculosis. Conclusion: This work was revealed protein changes in resistance to pyrazinamide in clinical isolates of M. tuberculosis.

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