Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas Mar del Plata, Argentina.
Front Microbiol. 2015 Feb 6;6:39. doi: 10.3389/fmicb.2015.00039. eCollection 2015.
The function of membrane proteases range from general house-keeping to regulation of cellular processes. Although the biological role of these enzymes in archaea is poorly understood, some of them are implicated in the biogenesis of the archaeal cell envelope and surface structures. The membrane-bound ATP-dependent Lon protease is essential for cell viability and affects membrane carotenoid content in Haloferax volcanii. At least two different proteases are needed in this archaeon to accomplish the posttranslational modifications of the S-layer glycoprotein. The rhomboid protease RhoII is involved in the N-glycosylation of the S-layer protein with a sulfoquinovose-containing oligosaccharide while archaeosortase ArtA mediates the proteolytic processing coupled-lipid modification of this glycoprotein facilitating its attachment to the archaeal cell surface. Interestingly, two different signal peptidase I homologs exist in H. volcanii, Sec11a and Sec11b, which likely play distinct physiological roles. Type IV prepilin peptidase PibD processes flagellin/pilin precursors, being essential for the biogenesis and function of the archaellum and other cell surface structures in H. volcanii.
膜蛋白酶的功能范围从一般的管家功能到细胞过程的调节。尽管这些酶在古菌中的生物学作用还了解甚少，但它们中的一些与古菌细胞包膜和表面结构的生物发生有关。膜结合的 ATP 依赖性 Lon 蛋白酶对于细胞活力是必不可少的，并影响 Haloferax volcanii 中的膜类胡萝卜素含量。在这个古菌中，至少需要两种不同的蛋白酶来完成 S-层糖蛋白的翻译后修饰。菱形蛋白酶 RhoII 参与 S-层蛋白的 N-糖基化，带有含硫酸奎诺糖的寡糖，而 archaeosortase ArtA 介导该糖蛋白的蛋白水解加工和脂修饰，促进其附着到古菌细胞表面。有趣的是，H. volcanii 中存在两种不同的信号肽酶 I 同源物 Sec11a 和 Sec11b，它们可能发挥不同的生理作用。IV 型前原肽酶 PibD 处理鞭毛蛋白/菌毛前体，对于 H. volcanii 中菌毛和其他细胞表面结构的生物发生和功能是必不可少的。
