Polyphosphate kinase 1 is involved in formation, the morphology and ultramicrostructure of biofilm of Mycobacterium smegmatis and its survivability in macrophage

Cailin He; Bo Li; Zhen Gong; Sheng Huang; Xu Liu; Jiajun Wang; Jianping Xie; Tingyu Shi

doi:10.1016/j.heliyon.2023.e14513

Polyphosphate kinase 1 is involved in formation, the morphology and ultramicrostructure of biofilm of Mycobacterium smegmatis and its survivability in macrophage

Heliyon. 2023 Mar 17;9(3):e14513. doi: 10.1016/j.heliyon.2023.e14513. eCollection 2023 Mar.

Authors

Cailin He¹, Bo Li¹, Zhen Gong², Sheng Huang^{1

3}, Xu Liu^{1

3}, Jiajun Wang¹, Jianping Xie², Tingyu Shi^{1

4

3}

Affiliations

¹ Medical School of Hubei Minzu University, Enshi, 445000, China.
² Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China.
³ Institute of Selenium Science and Industry of Hubei Minzu University, Enshi, 445000, China.
⁴ Hubei Key Laboratory of Biological Resources Protection and Utilization, Enshi, 445000, China.

Abstract

The most unique characteristic of Mycobacterium tuberculosis is persistence in the human host, and the biofilm formation is related to the persistance. Polyphosphate (polyP) kinase 1 (PPK1) is conserved in Mycobacteria and is responsible for polyP synthesis. polyP is a chain molecule linked by high-energy phosphate bonds, which is considered to play a very important role in bacterial persistence. However, the relationship of PPK1 and mycobacterial biofilm formation is still adequately unclear. In current study, ppk1-deficient mutant (MT), ppk1-complemented (CT) and wild-type strains of M. smegmatis mc² 155 were used to investigate the formation, morphology and ultramicrostructure of the biofilm and to analyze the lipid levels and susceptibility to vancomycin antibiotic. And then WT, MT and CT strains were used to infect macrophages and to analyze the expression levels of various inflammatory factors, respectively. We found that PPK1 was required for M. smegmatis polyP production in vivo and polyP deficiency not only attenuated the biofilm formation, but also altered the phenotype and ultramicrostructure of the biofilm and reduced the cell lipid composition (except for C16.1 and C17.1, most of the fatty acid components from C8-C24). Moreover, the ppk1-deficient mutant was also significantly more sensitive to vancomycin which targets the cell wall, and its ability to survive in macrophages was decreased, which was related to the change of the expression level of inflammatory factors in macrophage. This study demonstrates that the PPK1 can affect the biofilm structure through affecting the content of short chain fatty acid and promote intracellular survival of M. smegmatis by altering the expression of inflammatory factors. These findings establish a basis for investigating the role of PPK1 in the persistence of M. tuberculosis, and provide clues for treating latent infection of M. tuberculosis with PPK1 as a potential drug target.

Keywords: Biofilm formation; Inflammatory factor; Intracellular survival; Mycobacteria; Polyphosphate kinase.