MbtJ: An Iron Stress-Induced Acetyl Hydrolase/Esterase of Mycobacterium Tuberculosis Helps Bacteria to Survive During Iron Stress

Abstract

Aim: mbtJ from Mycobacterium tuberculosis H37Rv is a member of mbt A-J operon required for mycobactin biogenesis. Materials & methods: The esterase/acetyl-hydrolase activity of mbtJ was determined by pNP-esters/native-PAGE and expression under iron stress by quantitative-PCR. Effect of gene on growth/survival of Mycobacterium was studied using antisense. Its effect on morphology, growth/infection was studied in Mycobacterium smegmatis. Results: It showed acetyl hydrolase/esterase activity at pH 8.0 and 50°C with pNP-butyrate. Its expression was upregulated under iron stress. The antisense inhibited the survival of bacterium during iron stress. Expression of mbtJ changed colony morphology and enhanced the growth/infection in M. smegmatis. Conclusion: mbtJ, an acetyl-hydrolase/esterase, enhanced the survival of M. tuberculosis under iron stress, affected the growth/infection efficiency in M. smegmatis, suggesting its pivotal role in the intracellular survival of bacterium.

Keywords:

• α/β hydrolase
• acetyl hydrolase
• esterase
• iron stress
• Mycobacterium tuberculosis
• pVV16 shuttle vector

Author contributions

Jagdeep Kaur conceived the idea, designed the study, supervised the work and edited the final draft of the manuscript. M Chownk managed the literature searches, performed the cloning, expression, purification, biochemical and biophysical characterization, expression study under iron stress and wrote the first draft of the manuscript. Jashandeep Kaur carried out the antisense related study. K Singh helped in antisense study and proofread the manuscript. All authors have read and approved the final manuscript.

Financial & competing interests disclosure

The authors acknowledge the research grant sanctioned by the Indian Council for Medical Research to Jagdeep Kaur, UGC-BSR fellowship to M Chownk and Council of Scientific and Industrial Research (CSIR) fellowship to Jashandeep Kaur. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

The authors acknowledge the research grant sanctioned by the Indian Council for Medical Research to Jagdeep Kaur, UGC-BSR fellowship to M Chownk and Council of Scientific and Industrial Research (CSIR) fellowship to Jashandeep Kaur. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed