A Novel Lipoate-Protein Ligase, Mhp-LplJ, Is Required for Lipoic Acid Metabolism in Mycoplasma hyopneumoniae.

Jin Jin,Huanhuan Liu,Henggui Liu,Huan Chen,Dongfang Shi,Jiuqing Xin,Kemeng Zhu,Ning Wang

doi:10.3389/fmicb.2020.631433

Abstract

Lipoic acid is a conserved cofactor necessary for the activation of several critical enzyme complexes in the aerobic metabolism of 2-oxoacids and one-carbon metabolism. Lipoate metabolism enzymes are key for lipoic acid biosynthesis and salvage. In this study, we found that Mycoplasma hyopneumoniae (M. hyopneumoniae) Mhp-Lpl, which had been previously shown to have lipoate-protein ligase activity against glycine cleavage system H protein (GcvH) in vitro, did not lipoylate the lipoate-dependent subunit of dihydrolipoamide dehydrogenase (PdhD). Further studies indicated that a new putative lipoate-protein ligase in M. hyopneumoniae, MHP_RS00640 (Mhp-LplJ), catalyzes free lipoic acid attachment to PdhD in vitro. In a model organism, Mhp-LplJ exhibited lipoate and octanoate ligase activities against PdhD. When the enzyme activity of Mhp-LplJ was disrupted by lipoic acid analogs, 8-bromooctanoic acid (8-BrO) and 6,8-dichlorooctanoate (6,8-diClO), M. hyopneumoniae growth was arrested in vitro. Taken together, these results indicate that Mhp-LplJ plays a vital role in lipoic acid metabolism of M. hyopneumoniae, which is of great significance to further understand the metabolism of M. hyopneumoniae and develop new antimicrobials against it.

Highlights

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the causative agent of enzootic pneumonia (EP) and is widespread in pig herds (Mulcock, 1965; Maes et al, 1996)
We first model the structure of the Mhp-lipoate-protein ligase J (LplJ) protein using the Swiss-Model server with lipoate-protein ligase A (LplA) of Streptococcus pneumoniae (S. pneumoniae) (PDBid: 1vqz) as the modeling template, which shows the highest reliability with a global model quality estimation (GMQE) value of 0.72
The MhpLplJ prediction model has a typical structure of lipoate-protein ligase, consisting of a large N-terminal domain and a small C-terminal domain, and the two domains are linked by a short polypeptide chain (Figure 3C)

Summary

Introduction

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the causative agent of enzootic pneumonia (EP) and is widespread in pig herds (Mulcock, 1965; Maes et al, 1996). Despite the low direct mortality, immunosuppression caused by M. hyopneumoniae and secondary infections by other pathogens greatly increase morbidity and mortality (Yu et al, 2018). Increasing evidence indicates that M. hyopneumoniae infection is associated with porcine respiratory disease complex (PRDC), the mechanisms of PRDC caused by M. hyopneumoniae are barely understood (Maes et al, 2008; Jeffrey et al, 2012). Lipoate-Protein Ligase of Mycoplasma hyopneumoniae and medication, but the effects of prevention and treatment of this disease are barely satisfactory (Takeuti et al, 2017). Some studies have shown that current commercial vaccines only slow down M. hyopneumoniae transmission and are unable to prevent colonization of M. hyopneumoniae and the development of lung lesions (Matthijs et al, 2019). It is imperative to develop new vaccines and medicines

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Conclusion