Characterization of Conserved and Novel Septal Factors in Mycobacterium smegmatis
Characterization of Conserved and Novel Septal Factors in Mycobacterium smegmatis
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DOI：
10.1128/jb.00649-17
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发表时间：
2018-03-01
影响因子：
3.2
通讯作者：
Boutte, Cara C.
中科院分区：
文献类型：
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作者：
Wu, Katherine J.;Zhang, Jenna;Boutte, Cara C.
细菌的分离需要细胞壁生物合成和水解酶的协调调节，以便在不损害现有细胞壁完整性的情况下适当地构建新的隔膜交叉壁。具有不同生长方式和不同细胞壁类型的细菌需要不同的调节因子来调节细胞生长和分裂过程。分枝杆菌具有细胞壁结构和生长方式，与经过充分研究的模式生物不同，并使用几种不同的调节机制。在这里，我们利用耻垢分枝杆菌，鉴定和表征了保守的细胞分裂调节因子FtsL和FtsB的同源物，并表明它们在大肠杆菌中的功能与它们的同源物相似。我们确定了一些以前未描述的可能参与细胞壁调节的间隔局部因子。其中之一，SepIVA，有一个DivIVA结构域，是分枝杆菌分离所必需的，并且定位于隔膜和胞内膜结构域。我们提出SepIVA是细胞壁前体酶的调节剂，有助于隔膜交叉壁的构建，类似于另一个分枝杆菌DivIVA同源物Wag31的假定延伸功能。构建细菌细胞壁的酶对细胞存活至关重要，但如果调节不当，可能导致细胞裂解；因此，它们的监管者也必不可少。在以不同方式生长的细菌中，这些调节因子的数量和性质可能会有所不同。分枝杆菌是一种具有细胞壁的属，其组成和结构与那些经过充分研究的模式生物有很大的不同。在这项工作中，我们鉴定和表征了一些调节分枝杆菌细胞壁的蛋白质。我们发现，这些调节因子中的一些似乎与它们在进化上遥远的物种（如大肠杆菌）的结构同源物在功能上是保守的，但其他蛋白质具有关键的调节功能，可能是放线菌所特有的。
Septation in bacteria requires coordinated regulation of cell wall biosynthesis and hydrolysis enzymes so that new septal cross-wall can be appropriately constructed without compromising the integrity of the existing cell wall. Bacteria with different modes of growth and different types of cell wall require different regulators to mediate cell growth and division processes. Mycobacteria have both a cell wall structure and a mode of growth that are distinct from well-studied model organisms and use several different regulatory mechanisms. Here, using Mycobacterium smegmatis, we identify and characterize homologs of the conserved cell division regulators FtsL and FtsB, and show that they appear to function similarly to their homologs in Escherichia coli. We identify a number of previously undescribed septally localized factors which could be involved in cell wall regulation. One of these, SepIVA, has a DivIVA domain, is required for mycobacterial septation, and is localized to the septum and the intracellular membrane domain. We propose that SepIVA is a regulator of cell wall precursor enzymes that contribute to construction of the septal cross-wall, similar to the putative elongation function of the other mycobacterial DivIVA homolog, Wag31.IMPORTANCE The enzymes that build bacterial cell walls are essential for cell survival but can cause cell lysis if misregulated; thus, their regulators are also essential. The number and nature of these regulators is likely to vary in bacteria that grow in different ways. The mycobacteria are a genus that have a cell wall whose composition and construction vary greatly from those of well-studied model organisms. In this work, we identify and characterize some of the proteins that regulate the mycobacterial cell wall. We find that some of these regulators appear to be functionally conserved with their structural homologs in evolutionarily distant species such as Escherichia coli, but other proteins have critical regulatory functions that may be unique to the actinomycetes.