The Smu0630 protein (AtlA) was recently shown to be involved in cell separation, biofilm formation, and autolysis. Here, transcriptional studies revealed that atlA is part of a multigene operon under the control of at least three promoters. The morphology and biofilm-forming capacity of a nonpolar altA mutant could be restored to that of the wild-type strain by adding purified AtlA protein to the medium. A series of truncated derivatives of AtlA revealed that full activity required the C terminus and repeat regions. AtlA was cell associated and readily extractable from with sodium dodecyl sulfate. Of particular interest, the surface protein profile of AtlA-deficient strains was dramatically altered compared to the wild-type strain, as was the nature of the association of the multifunctional adhesin P1 with the cell wall. In addition, AtlA-deficient strains failed to develop competence as effectively as the parental strain. Mutation of thmA, which can be cotranscribed with atlA and encodes a putative pore-forming protein, resulted in a phenotype very similar to that of the AtlA-deficient strain. ThmA was also shown to be required for efficient processing of AtlA to its mature form, and treatment of the thmA mutant strain with full-length AtlA protein did not restore normal cell separation and biofilm formation. The effects of mutating other genes in the operon on cell division, biofilm formation, or AtlA biogenesis were not as profound. This study reveals that AtlA is a surface-associated protein that plays a critical role in the network connecting cell surface biogenesis, biofilm formation, genetic competence, and autolysis.

译文

:最近发现,Smu0630蛋白(AtlA)与细胞分离,生物膜形成和自溶有关。在这里,转录研究表明atlA是多基因操纵子的一部分,在至少三个启动子的控制下。通过向培养基中添加纯化的AtlA蛋白,可以将非极性altA突变体的形态和生物膜形成能力恢复为野生型菌株。 AtlA的一系列截短的衍生物表明,完整的活性需要C末端和重复区域。 AtlA与细胞相关,可以很容易地用十二烷基硫酸钠提取。特别令人感兴趣的是,与野生型菌株相比,AtlA缺陷型菌株的表面蛋白质谱发生了巨大变化,多功能黏附素P1与细胞壁的缔合性质也是如此。另外,缺乏AtlA的菌株不能像亲本菌株一样有效地发展能力。可以与atlA共转录并编码推定的成孔蛋白的thmA突变产生的表型与缺乏AtlA的菌株非常相似。还显示ThmA是有效将AtlA加工成其成熟形式所必需的,并且用全长AtlA蛋白处理thmA突变株不能恢复正常的细胞分离和生物膜形成。操纵子中其他基因突变对细胞分裂,生物膜形成或AtlA生物发生的影响并不那么深远。这项研究表明,AtlA是一种表面相关蛋白,在连接细胞表面生物发生,生物膜形成,遗传能力和自溶作用的网络中起关键作用。

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