Mab_3083c Is a Homologue of RNase J and Plays a Role in Colony Morphotype, Aggregation, and Sliding Motility of Mycobacterium abscessus.

Ting-Yu Liu,Shiau-Ting Hu,Yih-Yuan Chen,Sheng-Hui Tsai,Jenn-Wei Chen,Yu-Ching Wang

doi:10.3390/microorganisms9040676

Abstract

Mycobacterium abscessus is an opportunistic pathogen causing human diseases, especially in immunocompromised patients. M. abscessus strains with a rough morphotype are more virulent than those with a smooth morphotype. Morphotype switch may occur during a clinical infection. To investigate the genes involved in colony morphotype switching, we performed transposon mutagenesis in a rough clinical strain of M. abscessus. A morphotype switching mutant (smooth) named mab_3083c::Tn was obtained. This mutant was found to have a lower aggregative ability and a higher sliding motility than the wild type strain. However, its glycopeptidolipid (GPL) content remained the same as those of the wild type. Complementation of the mutant with a functional mab_3083c gene reverted its morphotype back to rough, indicating that mab_3083c is associated with colony morphology of M. abscessus. Bioinformatic analyses showed that mab_3083c has a 75.4% identity in amino acid sequence with the well-characterized ribonuclease J (RNase J) of M. smegmatis (RNase JMsmeg). Complementation of the mutant with the RNase J gene of M. smegmatis also switched its colony morphology from smooth back to rough. These results suggest that Mab_3083c is a homologue of RNase J and involved in regulating M. abscessus colony morphotype switching.

Highlights

Mycobacterium abscessus is a rapid-growing nontuberculous Mycobacterium (NTM) and is often present in soil and water [1,2]
We investigated the role of the mab_3083c gene, homologue of ribonuclease J (RNase J), in colony morphology switching and surface-associated properties of M. abscessus
M. smegmatis mc2 155 was purchased from the American Type Culture Collection (ATCC), and the clinical strain M. abscessus cs1c was obtained from the Veterans General

Summary

Introduction

Mycobacterium abscessus is a rapid-growing nontuberculous Mycobacterium (NTM) and is often present in soil and water [1,2]. The prevalence of M. abscessus infection is increasing in hospitals in Taiwan [9,10]. Because M. abscessus is highly resistant to multiple antibiotics, treatment of M. abscessus infections is often difficult [11,12]. It has been shown that M. abscessus is resistant to first-line anti-tuberculosis agents such as rifampin and ethambutol [13,14]. Treatment for M. abscessus infection consists of intravenous amikacin combined with oral macrolide such as clarithromycin, as suggested by the American Thoracic Society and the Infectious Diseases Society of America [4]

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Discussion

Conclusion