Small Heat Shock Protein16.3 of Mycobacterium tuberculosis: After Two Decades of Functional Characterization

Small heat shock proteins (sHSPs) are one of the five families of proteins acting as molecular chaperone. sHSPs possess a universally conserved alpha-crystallin domain, hence, also known as alpha-crystallin family. Mycobacterium tuberculosis (MTB) is an etiological agent of tuberculosis, a disease claiming million of lives every year across the world. MTB has two sHSPs: sHSP16.3 (a 16.3 kDa protein) and Acr2 (a 17.8 kDa protein). Of these, sHSP16.3 has been reported to be crucial for survival of MTB during prolonged period of dormancy, in addition to indispensable role in its growth, virulence and cell wall thickening. Additionally, this mycobacterial protein is also beneficial for host as well. Due to strong immunogenic properties and consistent presence in patients sera, sHSP16.3 has largely been implicated in vaccine development and diagnosis of latent and active infections of MTB in the clinical cases of TB. Recently, our study provided the substantial evidence to exploit this mycobacterial protein as a good drug target for developing novel therapeutic intervention. In the present review, a comprehensive analysis of various attributes of sHSP16.3 has been done and major gaps in area have been highlighted for future course of action.