Chauhan Anu, Singh Nirbhay, Kumar Ram, Kushwaha Neeti Kumari, Prajapati V M, Singh Sudheer Kumar
Molecular Microbiology and Immunology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Molecular Microbiology and Immunology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226031, India.
Tuberculosis (Edinb). 2023 Jul;141:102352. doi: 10.1016/j.tube.2023.102352. Epub 2023 May 24.
Mycobacterial galactan biosynthesis is critical for cell viability and growth, therefore an effort was made to study galactofuranosyl transferase 1, encoded by MRA_3822 in Mycobacterium tuberculosis H37Ra (Mtb-Ra). Galactofuranosyl transferases are involved in the biosynthesis of mycobacterial cell wall galactan chain and have been shown to be essential for in-vitro growth of Mycobacterium tuberculosis. In Mtb-Ra and Mycobacterium tuberculosis H37Rv (Mtb-Rv), two galactofuranosyl transferases are present, GlfT1 acts as initiator of galactan biosynthesis and GlfT2 continues with the subsequent polymerization events. GlfT2 has been well studied however GlfT1 inhibition/down-regulation and its effect on mycobacterial survival fitness has not been evaluated. To study the Mtb-Ra survival after GlfT1 silencing, Mtb-Ra knockdown and complemented strains were developed. In this study we show that GlfT1 down-regulation leads to increased susceptibility to ethambutol. Expression of glfT1 was up-regulated in the presence of ethambutol, and also in the presence of oxidative and nitrosative stress and upon exposure to low pH. Also, reduced biofilm formation, increased accumulation of ethidium bromide, and reduced tolerance to peroxide, nitric oxide and acid stress, were observed. The present study also demonstrates that GlfT1 down-regulation leads to reduced survival of Mtb-Ra in macrophages and in mice.
分枝杆菌的半乳聚糖生物合成对细胞活力和生长至关重要，因此我们努力研究结核分枝杆菌H37Ra（Mtb-Ra）中由MRA_3822编码的半乳呋喃糖基转移酶1。半乳呋喃糖基转移酶参与分枝杆菌细胞壁半乳聚糖链的生物合成，并且已被证明对结核分枝杆菌的体外生长至关重要。在Mtb-Ra和结核分枝杆菌H37Rv（Mtb-Rv）中，存在两种半乳呋喃糖基转移酶，GlfT1作为半乳聚糖生物合成的起始物，而GlfT2则继续后续的聚合反应。GlfT2已得到充分研究，然而GlfT1的抑制/下调及其对分枝杆菌生存适应性的影响尚未得到评估。为了研究GlfT1沉默后Mtb-Ra的存活情况，构建了Mtb-Ra敲低和互补菌株。在本研究中，我们表明GlfT1下调导致对乙胺丁醇的敏感性增加。在乙胺丁醇存在下，以及在氧化和亚硝化应激存在下以及暴露于低pH时，glfT1的表达上调。此外，还观察到生物膜形成减少、溴化乙锭积累增加以及对过氧化物、一氧化氮和酸应激的耐受性降低。本研究还表明，GlfT1下调导致Mtb-Ra在巨噬细胞和小鼠中的存活率降低。
