Yu Chunxiao, Ruiz Teresa, Lenox Christopher, Mintz Keith P
Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA.
J Bacteriol. 2008 May;190(9):3098-109. doi: 10.1128/JB.01709-07. Epub 2008 Feb 29.
Extracellular matrix protein adhesin A (EmaA) is a 202-kDa nonfimbrial adhesin, which mediates the adhesion of the oral pathogen Aggregatibacter actinomycetemcomitans to collagen. EmaA oligomers form surface antenna-like protrusions consisting of a long helical rod with an ellipsoidal ending. The functional analysis of in-frame emaA deletion mutants has located the collagen binding activity to the amino terminus of the protein corresponding to amino acids 70 to 386. The level of collagen binding of this deletion mutant was comparable to the emaA mutant strain. Transmission electron microscopy studies indicate that the first 330 amino acids of the mature protein form the ellipsoidal ending of the EmaA protrusions, where the activity resides. Amino acid substitution analysis within this sequence has identified a critical amino acid, which is essential for the formation of the ellipsoidal ending and for collagen binding activity.
细胞外基质蛋白黏附素A（EmaA）是一种202千道尔顿的非菌毛黏附素，它介导口腔病原体伴放线聚集杆菌与胶原蛋白的黏附。EmaA寡聚体形成表面天线样突起，由带有椭圆形末端的长螺旋杆组成。对框内emaA缺失突变体的功能分析已将胶原蛋白结合活性定位到该蛋白质对应于氨基酸70至386的氨基末端。该缺失突变体的胶原蛋白结合水平与emaA突变菌株相当。透射电子显微镜研究表明，成熟蛋白的前330个氨基酸形成EmaA突起的椭圆形末端，活性就存在于此。该序列内的氨基酸取代分析已鉴定出一个关键氨基酸，它对于椭圆形末端的形成和胶原蛋白结合活性至关重要。
