EmbB and EmbC regulate the sensitivity of Mycobacterium abscessus to echinomycin

Jing He; Yamin Gao; Jingyun Wang; H. M. Adnan Hameed; Shuai Wang; Cuiting Fang; Xirong Tian; Jingran Zhang; Xingli Han; Yanan Ju; Yaoju Tan; Junying Ma; Jianhua Ju; Jinxing Hu; Jianxiong Liu; Tianyu Zhang

doi:10.1002/mlf2.12139

mLife ›› 2024, Vol. 3 ›› Issue (3) : 459 -470. DOI: 10.1002/mlf2.12139

ORIGINAL RESEARCH

EmbB and EmbC regulate the sensitivity of Mycobacterium abscessus to echinomycin

Jing He ¹^,²^,³^,⁴
, Yamin Gao ²^,³^,⁴^,⁵
, Jingyun Wang ⁶^,⁷
, H. M. Adnan Hameed ²^,³^,⁴^,⁵^,^†
, Shuai Wang ²^,³^,⁴^,⁵
, Cuiting Fang ²^,³^,⁴^,⁵
, Xirong Tian ²^,³^,⁴^,⁵
, Jingran Zhang ²^,³^,⁴^,⁸
, Xingli Han ²^,³^,⁴^,⁵
, Yanan Ju ²^,³^,⁴^,⁸
, Yaoju Tan ⁹
, Junying Ma ⁷
, Jianhua Ju ⁷
, Jinxing Hu ⁹^,^†
, Jianxiong Liu ⁹^,^†
, Tianyu Zhang ¹^,²^,³^,⁴^,⁵^,⁸^,⁹^,^†

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Abstract

Treatment of Mycobacterium abscessus (Mab) infections is very challenging due to its intrinsic resistance to most available drugs. Therefore, it is crucial to discover novel anti-Mab drugs. In this study, we explored an intrinsic resistance mechanism through which Mab resists echinomycin (ECH). ECH showed activity against Mab at a minimum inhibitory concentration (MIC) of 2 µg/ml. A ΔembC strain in which the embC gene was knocked out showed hypersensitivity to ECH (MIC: 0.0078–0.0156 µg/ml). The MICs of ECH-resistant strains screened with reference to ΔembC ranged from 0.25 to 1 µg/ml. Mutations in EmbB, including D306A, D306N, R350G, V555I, and G581S, increased the Mab’s resistance to ECH when overexpressed in ΔembC individually (MIC: 0.25–0.5 µg/ml). These EmbB mutants, edited using the CRISPR/Cpf1 system, showed heightened resistance to ECH (MIC: 0.25–0.5 µg/ml). The permeability of these Mab strains with edited genes and overexpression was reduced, as evidenced by an ethidium bromide accumulation assay, but it remained significantly higher than that of the parent Mab. In summary, our study demonstrates that ECH exerts potent anti-Mab activity and confirms that EmbB and EmbC are implicated in Mab’s sensitivity to ECH. Mutation in EmbB may partially compensate for a loss of EmbC function.

Keywords

echinomycin / EmbB / EmbC / functional compensation / Mycobacterium abscessus

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Jing He, Yamin Gao, Jingyun Wang, H. M. Adnan Hameed, Shuai Wang, Cuiting Fang, Xirong Tian, Jingran Zhang, Xingli Han, Yanan Ju, Yaoju Tan, Junying Ma, Jianhua Ju, Jinxing Hu, Jianxiong Liu, Tianyu Zhang. EmbB and EmbC regulate the sensitivity of Mycobacterium abscessus to echinomycin. mLife, 2024, 3(3): 459-470 DOI:10.1002/mlf2.12139