Cloning and functional analysis of Asa373, a novel adhesin unrelated to the other sex pheromone plasmid‐encoded aggregation substances of Enterococcus faecalis
Cloning and functional analysis of Asa373, a novel adhesin unrelated to the other sex pheromone plasmid‐encoded aggregation substances of Enterococcus faecalis
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与粪肠球菌其他性信息素质粒编码聚集物质无关的新型粘附素Asa373的克隆和功能分析
作者：
A. Muscholl
粪肠球菌的PAM373不同于其他各种性信息素质粒的代表，因为它编码一种集束介导的粘附素，Asa373，与这一质粒类典型的高度保守的聚集物质无关。利用一种新的通用克隆策略和相应基因的测序证实了Asa373代表了一种嵌入在DNA序列中的新型粘附素，与性信息素质粒pPD1非常相似。为了证明这个相对较小的蛋白(75.6kDa vs137 kDa)在细胞聚集中的特殊功能，构建了pERM-EX1表达载体，使其能够在粪肠球菌中可靠、稳定地表达。Asa373在粪肠球菌中的表达确实导致了结构性聚集，而原始PAM373中该基因的非极性破坏则取消了聚集能力。在结合物质缺陷的菌株(INY3000)中的表达-对于其他聚集物质构成交配伙伴上的附着位置-并没有改变Asa373依赖的聚集；这意味着这种粘附素在细胞间相互作用中有一种单独的机制。Asa373的一些氨基酸基序将该蛋白与口腔链球菌的粘附素和其他细胞表面蛋白联系在一起。将asa373的前导序列与其他几种聚集物质的前导序列进行比较，发现了一个高度保守的翻译单位，可能参与了asa373的表达调控。
pAM373 of Enterococcus faecalis deviates from the various other representatives of sex pheromone plasmids in that it encodes a clumping‐mediating adhesin, Asa373, unrelated to the highly conserved aggregation substances typical of this plasmid class. The use of a new general cloning strategy and sequencing of the corresponding gene has confirmed that Asa373 represents a novel type of adhesin embedded in a DNA sequence very similar to sex pheromone plasmid pPD1. To prove the specific function of the relatively small protein (75.6 kDa vs 137 kDa for pAD1‐encoded Asa1) in cell aggregation, an expression vector, pERM‐ex1, was constructed, allowing reliable and stable expression of proteins in E. faecalis. The expression of Asa373 in E. faecalis indeed resulted in constitutive clumping, whereas non‐polar disruption of the gene in the original pAM373 abolished clumping capacity. Expression in a strain (INY3000) defective in binding substance — which for the other aggregation substances constitutes the attachment site on the mating partner — did not alter Asa373‐dependent clumping; this implies a separate mechanism in cell–cell interaction for this adhesin. Some amino acid motifs of Asa373 link the protein to adhesins of oral streptococci and other cell surface proteins. Comparison of the leader sequence of asa373 with those of several other aggregation substances revealed a highly conserved translational unit possibly involved in the regulation of asa373 expression.
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影响因子：
2.6
作者：
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通讯作者：
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影响因子：
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作者：
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DOI：
--
发表时间：
1989
期刊：
The American journal of pathology
影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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