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Open Access Highly Accessed Research article

A peptide fragment from the human COX3 protein disrupts association of Mycobacterium tuberculosis virulence proteins ESAT-6 and CFP10, inhibits mycobacterial growth and mounts protective immune response

Sachin Kumar Samuchiwal1, Sultan Tousif234, Dhiraj Kumar Singh2, Arun Kumar2, Anamika Ghosh1, Kuhulika Bhalla1, Prem Prakash1, Sushil Kumar1, Maitree Bhattacharyya3, Prashini Moodley4, Gobardhan Das4* and Anand Ranganathan1*

Author Affiliations

1 Recombinant Gene Products Group, International Centre for Genetic Engineering and Biotechnology, ICGEB, Aruna Asaf Ali Marg, New Delhi 110067, India

2 Immunology Group, International Centre for Genetic Engineering and Biotechnology, ICGEB, Aruna Asaf Ali Marg, New Delhi 110067, India

3 Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700 019, India

4 School of Laboratory Medicine, College of Health Sciences, University of Kwazulu-Natal, Durban, South Africa

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BMC Infectious Diseases 2014, 14:355  doi:10.1186/1471-2334-14-355

Published: 1 July 2014

Abstract

Background

Tuberculosis (TB) is one of the most prevalent infectious diseases affecting millions worldwide. The currently available anti-TB drugs and vaccines have proved insufficient to contain this scourge, necessitating an urgent need for identification of novel drug targets and therapeutic strategies. The disruption of crucial protein-protein interactions, especially those that are responsible for virulence in Mycobacterium tuberculosis – for example the ESAT-6:CFP10 complex – are a worthy pursuit in this direction.

Methods

We therefore sought to improvise a method to attenuate M. tuberculosis while retaining the latter’s antigenic properties. We screened peptide libraries for potent ESAT-6 binders capable of dissociating CFP10 from ESAT-6. We assessed the disruption by a peptide named HCL2, of the ESAT-6:CFP10 complex and studied its effects on mycobacterial survival and virulence.

Results

We found that HCL2, derived from the human cytochrome c oxidase subunit 3 (COX3) protein, disrupts ESAT-6:CFP10 complex, binds ESAT-6 potently, disintegrates bacterial cell wall and inhibits extracellular as well as intracellular mycobacterial growth. In addition, an HCL2 expressing M. tuberculosis strain induces both Th1 and Th17 host protective responses.

Conclusions

Disruption of ESAT-6:CFP10 association could, therefore, be an alternate method for attenuating M. tuberculosis, and a possible route towards future vaccine generation.

Keywords:
Tuberculosis; Human COX3; ESAT-6; CFP10; Protein-protein interactions; Th1; Th17