Lipid Anchoring of Archaeosortase Substrates and Midcell Growth in Haloarchaea
Lipid Anchoring of Archaeosortase Substrates and Midcell Growth in Haloarchaea
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DOI：
10.1128/mbio.00349-20
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发表时间：
2020-03-01
期刊：
影响因子：
6.4
通讯作者：
Pohlschroder, Mechthild
中科院分区：
文献类型：
--
作者：
Abdul-Halim, Mohd Farid;Schulze, Stefan;Pohlschroder, Mechthild
古细菌细胞质膜为许多表面蛋白质提供了一个锚。最近，一种新的膜锚定机制，涉及肽酶，archaeosortase A（阿尔塔），和C-末端的表面蛋白质的脂质附着被确定在模型古菌Holoferox volcano ii。阿尔塔是最佳细胞生长和形态发生所必需的，S层糖蛋白（SLG）是H. volcanii细胞壁是这种锚定机制的目标之一。然而，阿尔塔的功能和调节究竟如何控制细胞生长和形态发生仍然难以捉摸。在这里，我们报告说，古细菌的同源细菌磷脂酰丝氨酸合成酶（PssA）和磷脂酰丝氨酸脱羧酶（PssD）参与ArtA依赖的蛋白质成熟。缺乏HvPssA或HvPssD的Holoferox volcanii菌株表现出与Delta阿尔塔突变体相似的运动性、生长和形态表型。此外，我们显示在Delta hvpssA突变体中与SLG的共价脂质附着的损失，并且在Delta hvossA和Delta hvossD突变体菌株中阿尔塔底物HVO_0405的蛋白水解切割被阻断。引人注目的是，阿尔塔、HvPssA和HvPssD绿色荧光蛋白（GFP）融合体共定位于H. volcanii细胞，强烈支持它们参与相同的途径。最后，我们已经表明，SLG也被招募到中间细胞之前，被分泌和脂质锚定在细胞外表面。总的来说，我们的数据表明，嗜盐古菌使用的主要表面处理热点细胞伸长，分裂，和形状determination.IMPORTANCE生化过程的亚细胞组织在空间和时间仍然是古菌细胞生物学中最神秘的课题之一。尽管盐古菌在很大程度上依赖于共价脂质锚定来包覆细胞包膜，但关于细胞如何协调从头合成以及在整个细胞周期中插入这种蛋白质层的情况知之甚少。在这里，我们报告了两个新的贡献者的ArtA依赖性脂质介导的蛋白锚定到细胞表面，HvPssA和HvPssD的鉴定。阿尔塔、HvPssA和HvPssD以及SLG在生长和胞质分裂期间显示出中细胞定位，表明盐古菌细胞限制磷脂加工以促进中细胞伸长。我们的发现对细胞表面的生物发生具有重要意义。
The archaeal cytoplasmic membrane provides an anchor for many surface proteins. Recently, a novel membrane anchoring mechanism involving a peptidase, archaeosortase A (ArtA), and C-terminal lipid attachment of surface proteins was identified in the model archaeon Holoferox volcanii. ArtA is required for optimal cell growth and morphogenesis, and the S-layer glycoprotein (SLG), the sole component of the H. volcanii cell wall, is one of the targets for this anchoring mechanism. However, how exactly ArtA function and regulation control cell growth and morphogenesis is still elusive. Here, we report that archaeal homologs to the bacterial phosphatidylserine synthase (PssA) and phosphatidylserine decarboxylase (PssD) are involved in ArtA-dependent protein maturation. Holoferox volcanii strains lacking either HvPssA or HvPssD exhibited motility, growth, and morphological phenotypes similar to those of an Delta artA mutant. Moreover, we showed a loss of covalent lipid attachment to SLG in the Delta hvpssA mutant and that proteolytic cleavage of the ArtA substrate HVO_0405 was blocked in the Delta hvossA and Delta hvossD mutant strains. Strikingly, ArtA, HvPssA, and HvPssD green fluorescent protein (GFP) fusions colocalized to the midcell position of H. volcanii cells, strongly supporting that they are involved in the same pathway. Finally, we have shown that the SLG is also recruited to the midcell before being secreted and lipid anchored at the cell outer surface. Collectively, our data suggest that haloarchaea use the midcell as the main surface processing hot spot for cell elongation, division, and shape determination.IMPORTANCE The subcellular organization of biochemical processes in space and time is still one of the most mysterious topics in archaeal cell biology. Despite the fact that haloarchaea largely rely on covalent lipid anchoring to coat the cell envelope, little is known about how cells coordinate de novo synthesis and about the insertion of this proteinaceous layer throughout the cell cycle. Here, we report the identification of two novel contributors to ArtA-dependent lipid-mediated protein anchoring to the cell surface, HvPssA and HvPssD. ArtA, HvPssA, and HvPssD, as well as SLG, showed midcell localization during growth and cytokinesis, indicating that haloarchaeal cells confine phospholipid processing in order to promote midcell elongation. Our findings have important implications for the biogenesis of the cell surface.