Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
J Bacteriol. 2020 Aug 25;202(18). doi: 10.1128/JB.00277-20.
Mechanisms by which cells attach to a surface and form a biofilm are diverse and differ greatly among organisms. The Gram-negative gammaproteobacterium attaches to a surface through the localization of the large type 1-secreted RTX adhesin LapA to the outer surface of the cell. LapA localization to the cell surface is controlled by the activities of a periplasmic protease, LapG, and an inner membrane-spanning cyclic di-GMP-responsive effector protein, LapD. A previous study identified a second, LapA-like protein encoded in the Pf0-1 genome: Pfl01_1463. Here, we identified specific growth conditions under which Pfl01_1463, here called MapA (edium dhesion rotein ) is a functional adhesin contributing to biofilm formation. This adhesin, like LapA, appears to be secreted through a Lap-related type 1 secretion machinery, and its localization is controlled by LapD and LapG. However, differing roles of LapA and MapA in biofilm formation are achieved, at least in part, through the differences in the sequences of the two adhesins and different distributions of the expression of the and genes within a biofilm. LapA-like proteins are broadly distributed throughout the , and furthermore, LapA and MapA are well conserved among other species. Together, our data indicate that the mechanisms by which a cell forms a biofilm and the components of a biofilm matrix can differ depending on growth conditions and the matrix protein(s) expressed. Adhesins are critical for the formation and maturation of bacterial biofilms. We identify a second adhesin in , called MapA, which appears to play a role in biofilm maturation and whose regulation is distinct from the previously reported LapA adhesin, which is critical for biofilm initiation. Analysis of bacterial adhesins shows that LapA-like and MapA-like adhesins are found broadly in pseudomonads and related organisms, indicating that the utilization of different suites of adhesins may be broadly important in the .
细胞附着在表面并形成生物膜的机制多种多样，在不同生物体之间差异很大。革兰氏阴性γ变形菌通过将大型 I 型分泌 RTX 粘附素 LapA 定位到细胞外表面来附着在表面上。LapA 定位于细胞表面受周质蛋白酶 LapG 和跨内膜环二鸟苷酸（c-di-GMP）响应效应蛋白 LapD 的活性控制。先前的研究鉴定了 Pf0-1 基因组中编码的第二种 LapA 样蛋白： Pfl01_1463。在这里，我们确定了特定的生长条件，在这些条件下， Pfl01_1463（这里称为 MapA，即中等粘附蛋白）是一种有助于生物膜形成的功能性粘附素。这种粘附素，像 LapA 一样，似乎通过一种与 Lap 相关的 I 型分泌机制分泌，其定位受 LapD 和 LapG 控制。然而，LapA 和 MapA 在生物膜形成中的作用不同，至少部分原因是两种粘附素的序列不同，以及在生物膜内表达的 和 基因的分布不同。LapA 样蛋白在整个 中广泛分布，此外，LapA 和 MapA 在其他 物种中也很好地保守。总之，我们的数据表明，细胞形成生物膜的机制和生物膜基质的组成可以根据生长条件和表达的基质蛋白（s）而不同。粘附素对于细菌生物膜的形成和成熟至关重要。我们在 中鉴定了第二种粘附素，称为 MapA，它似乎在生物膜成熟中发挥作用，其调节与先前报道的对于生物膜起始至关重要的 LapA 粘附素不同。对细菌粘附素的分析表明，LapA 样和 MapA 样粘附素在假单胞菌和相关生物中广泛存在，这表明不同粘附素套件的利用可能在 中广泛重要。
