Multiple factors are involved in regulation of extracellular membrane vesicle biogenesis in Streptococcus mutans,Molecular Oral Microbiology

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Multiple factors are involved in regulation of extracellular membrane vesicle biogenesis in Streptococcus mutans
Molecular Oral Microbiology ( IF 2.8 ) Pub Date : 2020-10-10 , DOI: 10.1111/omi.12318
Zezhang T Wen ₁ , Ashton N Jorgensen ₁ , Xiaochang Huang ₁ , Kassapa Ellepola ₁ , Lynne Chapman ₁ , Hui Wu ₂ , L Jeannine Brady ₃

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Streptococcus mutans, a major etiological agent of human dental caries, produces membrane vesicles (MVs) that contain protein and extracellular DNA. In this study, functional genomics, along with in vitro biofilm models, was used to identify factors that regulate MV biogenesis. Our results showed that when added to growth medium, MVs significantly enhanced biofilm formation by S. mutans, especially during growth in sucrose. This effect occurred in the presence and absence of added human saliva. Functional genomics revealed several genes, including sfp, which have a major effect on S. mutans MVs. In Bacillus sp. sfp encodes a 4′‐phosphopantetheinyl transferase that contributes to surfactin biosynthesis and impacts vesiculogenesis. In S. mutans, sfp resides within the TnSmu2 Genomic Island that supports pigment production associated with oxidative stress tolerance. Compared to the UA159 parent, the Δsfp mutant, TW406, demonstrated a 1.74‐fold (p < .05) higher MV yield as measured by BCA protein assay. This mutant also displayed increased susceptibility to low pH and oxidative stressors, as demonstrated by acid killing and hydrogen peroxide challenge assays. Deficiency of bacA, a putative surfactin synthetase homolog within TnSmu2, and especially dac and pdeA that encode a di‐adenylyl cyclase and a phosphodiesterase, respectively, also significantly increased MV yield (p < .05). However, elimination of bacA2, a bacitracin synthetase homolog, resulted in a >1.5‐fold (p < .05) reduction of MV yield. These results demonstrate that S. mutans MV properties are regulated by genes within and outside of the TnSmu2 island, and that as a major particulate component of the biofilm matrix, MVs significantly influence biofilm formation.

中文翻译：

多种因素参与变形链球菌细胞外膜囊泡生物合成的调节

变形链球菌是人类龋齿的主要病原体，它产生含有蛋白质和细胞外 DNA 的膜囊泡 (MV)。在这项研究中，功能基因组学以及体外生物膜模型被用来识别调节 MV 生物发生的因素。我们的结果表明，当添加到生长培养基中时，MV 显着增强了变形链球菌的生物膜形成，特别是在蔗糖中生长期间。在添加或不添加人类唾液的情况下都会发生这种效应。功能基因组学揭示了包括sfp 在内的几个基因，它们对变形链球菌MV 有重大影响。在芽孢杆菌属中。 sfp编码 4'-磷酸泛酰胆碱转移酶，有助于表面活性素生物合成并影响囊泡发生。在变形链球菌中，sfp位于 TnSmu2 基因组岛内，支持与氧化应激耐受性相关的色素产生。通过 BCA 蛋白测定测量，与 UA159 亲本相比， Δsfp突变体 TW406 的 MV 产量高出 1.74 倍 ( p < .05)。该突变体还表现出对低 pH 值和氧化应激源的敏感性增加，如酸杀伤和过氧化氢激发试验所证明的那样。 bacA（ TnSmu2 内假定的表面活性素合成酶同源物）的缺乏，尤其是分别编码二腺苷酸环化酶和磷酸二酯酶的dac和pdeA的缺乏，也会显着增加 MV 产量 ( p < .05)。然而，消除bacA2（一种杆菌肽合成酶同源物）会导致 MV 产量减少 >1.5 倍 ( p < .05)。这些结果表明S. mutans MV 特性受 TnSmu2 岛内外的基因调节，作为生物膜基质的主要颗粒成分，MV 显着影响生物膜的形成。

更新日期：2020-10-10

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