PGA exopolysaccharide in biofilm formation and pathogenicity of Aggregatibacter a

描述（由申请方提供）：伴放线聚集杆菌（Aa）和几种病原菌附着于非生物表面，并产生外泌多糖，这些外泌多糖覆盖这些定殖表面上的细菌细胞。由Aa产生的胞外多糖由以下组成：1，6-连接的N-乙酰基-D-葡糖胺（GlcNAc）单位。Aa利用与E同源的四基因操纵子产生这种胞外多糖。coli pga、Y. pestis hms和S.伊卡在Aa中，操纵子pgaABCD携带由pagB编码的脱乙酰酶（EC 3.5.1.41）。我们的初步数据表明，酶PgaB具有从PGA的GlcNAc的N-乙酰基基团去除乙酰基基团的能力。更有趣的是，我们发现PgaB在Aa和S中分离生物膜并抑制其形成。表皮放线杆菌和胸膜肺炎放线杆菌。我们先前已经表明，也来自Aa的酶分散素B（Dsp B）通过外多糖（PGA）的解聚阻止几种革兰氏阴性和革兰氏阳性细菌物种的表面附着。与DspB不同，新发现的酶PgaB改变了PGA的电荷状态，这表明分离/抑制的机制可能是通过脱乙酰化增加聚合物上的正电荷。重要的是，脱乙酰化在生物膜去除中的作用， 在这些生物体中，特别是Aa中的形成研究不足。我们将使用Aa的PgaB作为模型系统来理解这些过程。我们的长期目标是了解PGA在Aa致病性中的作用。我们将使用体外和体内模型来检验PGA在Aa毒力中起关键作用的总体假设。具体而言，将实现以下目标： 研究：具体目标1。证明PGA脱乙酰酶PgaB对Aa生物膜形成至关重要。具体目标2a。证明PGA的乙酰化状态有助于Aa中生物膜的形成。具体目标2b。确定PGA有助于Aa致病性。

DESCRIPTION (provided by applicant): Aggregatibacter actinomycetemcomitans (Aa) and several pathogenic bacteria attach to abiotic surfaces and produce exopolysaccharide that immobilize the bacterial cells on these colonized surfaces. The exopolysaccharide produced by Aa is made up of ?-1,6-linked N-acetyl-D-glucosamine (GlcNAc) units. Aa produces this exopolysaccharide utilizing a four-gene operon homologous to E. coli pga, Y. pestis hms, and S. epidermidis ica. In Aa, the operon pgaABCD carries a deacetylase enzyme (EC 3.5.1.41) encoded by pagB. Our Preliminary Data show that the enzyme PgaB has the ability to remove acetyl groups from the N-acetyl groups of GlcNAc of PGA. More intriguingly, we discovered that PgaB detaches biofilms and inhibits their formation in Aa as well as S. epidermidis and Actinobacillus pleuropneumoniae. We have previously shown that an enzyme dispersin B (DspB) also from Aa prevents surface attachment of several Gram negative as well as Gram-positive bacterial species through depolymerization of the exopolysaccharide (PGA). Unlike DspB, the newly discovered enzyme PgaB alters the charge state of PGA suggesting that the mechanism of detachment/inhibition might be through the increase of positive charges on the polymer as a result of deacetylation. Importantly, the role of deacetylation in biofilm removal and formation is understudied in these organisms, especially Aa. We will use PgaB from Aa as a model system to understand these processes. Our long-range goal is to understand the role of PGA in Aa pathogenicity. We will use both in vitro as well as in vivo models to test the overall hypothesis that PGA plays a critical role in Aa virulence. Specifically, the following aims will be studied: Specific Aim 1. Demonstrate that PGA deacetylating enzyme PgaB is critical for Aa biofilm formation. Specific Aim 2a. Demonstrate that the state of acetylation of PGA contributes to the biofilm formation in Aa. Specific Aim 2b. Establish that PGA contributes to Aa pathogenicity.