KATG Gene in Isoniazid Resistant M.Tb

KATG Gene in Isoniazid Resistant M.Tb



Gusai H. Abdel Samad1, Solima M. A. Sabeel2,*, Walaa A. Abuelgassim3, Abeer E. Abdelltif 3,4, Wisam M. Osman3,Mona A. Haroun5, Somaya M. Soliman6, Sami. A. B. Salam1, Hamid. A. Hamdan7, Mohamed A. Hassan 3,8,9.


1 Department of Microbiology, university of Bahri, Sudan

2 Department of Microbiology,Faculty of Medical Laboratory Sciences, Ibn Sina University, Sudan

3 Department of Bioinformatics, Africa City of Technology, Sudan

4 Department of Computer Sciences, Najran University, KSA

5 Department of Histopathology, ALzaim AL-Azhari University, Sudan

6 Department of Microbiology Al borg Medical Laboratories, UAE

7 Department of environmental Health, University of Hail, KSA

8 Division of Molecular Genetics, University of Tuebingen, Germany 9University, HNO –universities Klink-Tuebingen (Germany)


*Corresponding author



Aims: To detect mutation(s) within KatG that responsible for converting MTB to INH resistance and to investigate the predicted protein’s stability. 

Background: Tuberculosis (TB) remains a major health problem caused by Mycobacterium tuberculosis (MTB) bacteria. It is infect approximately 10 million people annually according to WHO global TB report 2017. Isoniazid (INH) is a prodrug that activated by catalase peroxidase enzyme coded by KatG gene. It was considered as main chemotherapy used throughout the world to manage TB, therefore resistance of INH occur in strains with impaired KatG gene.

Methods: A total of 305 Mycobacterium tuberculosis strains from Abu-Anja hospital for chest disease were obtained and identified by conventional biochemical tests.  Genomic DNA were extracted, katG gene were amplified by PCR. Consecutive isolates (n = 20) of KatG gene hot regions were sequenced and analyzed through bioinformatics tool such as BLAST to check sequence similarity, BioEdit for sequence alignment, GeneMark S to  translate DNA sequence into amino acids, i-mutant to estimate protein stability, Chimera to predict the tertiary model of protein and phylogeny.fr to draw phylogenetic tree.

Results: 70% (14/20) of sequences revealed 100% identity with EGY-K361 strain retrieved from database with Accession No: KC49137 while 30% (6/20) revealed 99% of similarity in BLAST. BioEdit illustrate transversion from guanine in to cytosine that convert serine (SER) at codon 315 in to Threonine (THR). Stability of mutant protein was increased. On phylogenetic tree most of mutant strains accumulate in one subgroup except one strain reported as the out-group sequence.

Conclusion: In silico tools have great impact to understand genetic variation. The substitution changed efficiency of INH, therefore S315T could be used as rapid screening marker to diagnosis INH resistant for more effective treatment prescription.


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