Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans.
Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans.
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DOI：
10.1099/mic.0.000246
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发表时间：
2016-03
期刊：
影响因子：
1.5
通讯作者：
K. P. Smith;T. Ruiz;K. Mintz
中科院分区：
文献类型：
--
作者：
K. P. Smith;T. Ruiz;K. Mintz
牙周病原菌Aggregatibacter放线菌表面菌毛亚基的合成、分泌和组装对生物膜的形成是必不可少的。最近的一项定量蛋白质组学研究表明，内膜蛋白形态发生蛋白C(MORC)的菌毛分泌器蛋白的丰度取决于MORC。为了进一步研究MORC和菌毛之间的关系，我们鉴定并补充了菌毛产生的缺陷。转化菌株表达了含有编码WT菌毛亚基和前毛蛋白多肽酶基因的质粒，表现出菌毛细菌的所有特征，包括独特的星状菌落形态、健壮的生物膜形成、由离散的微菌落组成的生物膜结构和菌毛的存在。当相同的质粒被转化到MORC突变菌株中时，该细菌没有表现出菌毛菌株的任何表型。将这些研究扩展到自然菌毛的临床菌株表明，由此产生的morc突变株保持了菌毛菌株的特征菌落形态。然而，菌毛亚基的分泌减少，突变菌株表面的菌毛较少。此外，菌毛菌株的morc突变体表现出显著改变的生物膜微菌落结构，同时保持与亲本菌株相似的生物膜质量。这些结果表明，MORC影响放线菌伴生菌的菌毛分泌和微集落形成。
Fimbrial subunit synthesis, secretion and assembly on the surface of the periodontal pathogen Aggregatibacter actinomycetemcomitans are essential for biofilm formation. A recent quantitative proteomics study employing an afimbriated strain and a developed mutant isogenic for the inner-membrane protein morphogenesis protein C (MorC) revealed that the abundance of the proteins of the fimbrial secretion apparatus in the membrane is dependent on MorC. To investigate further the relationship between MorC and fimbriation, we identified and complemented the defect in fimbriae production in the afimbriated laboratory strain. The transformed strain expressing a plasmid containing genes encoding the WT fimbrial subunit and the prepilin peptidase displayed all of the hallmarks of a fimbriated bacterium including the distinct star-like colony morphology, robust biofilm formation, biofilm architecture composed of discrete microcolonies and the presence of fimbriae. When the identical plasmid was transformed into a morC mutant strain, the bacterium did not display any of the phenotypes of fimbriated strains. Extension of these studies to a naturally fimbriated clinical strain showed that the resulting morC mutant maintained the characteristic colony morphology of fimbriated strains. There was, however, a reduction in the secretion of fimbrial subunits, and fewer fimbriae were observed on the surface of the mutant strain. Furthermore, the morC mutant of the fimbriated strain displayed a significantly altered biofilm microcolony architecture, while maintaining a similar biofilm mass to the parent strain. These results suggest that MorC influences fimbrial secretion and microcolony formation in A. actinomycetemcomitans.