Balashova Nataliya V, Park Diane H, Patel Jigna K, Figurski David H, Kachlany Scott C
Department of Oral Biology, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
Infect Immun. 2007 Sep;75(9):4490-7. doi: 10.1128/IAI.00288-07. Epub 2007 Jul 16.
Aggregatibacter (Actinobacillus) actinomycetemcomitans is a gram-negative oral pathogen that is the etiologic agent of localized aggressive periodontitis and systemic infections. A. actinomycetemcomitans produces leukotoxin (LtxA), which is a member of the RTX (repeats in toxin) family of secreted bacterial toxins and is known to target human leukocytes and erythrocytes. To better understand how LtxA functions as a virulence factor, we sought to detect and study potential A. actinomycetemcomitans proteins that interact with LtxA. We found that Cu,Zn superoxide dismutase (SOD) interacts specifically with LtxA. Cu,Zn SOD was purified from A. actinomycetemcomitans to homogeneity and remained enzymatically active. Purified Cu,Zn SOD allowed us to isolate highly specific anti-Cu,Zn SOD antibody and this antibody was used to further confirm protein interaction. Cu,Zn SOD-deficient mutants displayed decreased survival in the presence of reactive oxygen and nitrogen species and could be complemented with wild-type Cu,Zn SOD in trans. We suggest that A. actinomycetemcomitans Cu,Zn SOD may protect both bacteria and LtxA from reactive species produced by host inflammatory cells during disease. This is the first example of a protein-protein interaction involving a bacterial Cu,Zn SOD.
伴放线聚集杆菌（放线杆菌属）是一种革兰氏阴性口腔病原体，是局限性侵袭性牙周炎和全身感染的病原体。伴放线聚集杆菌产生白细胞毒素（LtxA），它是分泌型细菌毒素RTX（毒素重复序列）家族的成员，已知可靶向人类白细胞和红细胞。为了更好地了解LtxA作为毒力因子的作用机制，我们试图检测和研究与LtxA相互作用的潜在伴放线聚集杆菌蛋白。我们发现铜锌超氧化物歧化酶（SOD）与LtxA特异性相互作用。从伴放线聚集杆菌中纯化出的铜锌SOD达到了均一性，并且仍具有酶活性。纯化的铜锌SOD使我们能够分离出高度特异性的抗铜锌SOD抗体，该抗体用于进一步确认蛋白质相互作用。缺乏铜锌SOD的突变体在活性氧和氮物种存在的情况下存活率降低，并且可以通过转导野生型铜锌SOD来互补。我们认为伴放线聚集杆菌的铜锌SOD可能在疾病期间保护细菌和LtxA免受宿主炎症细胞产生的活性物质的影响。这是涉及细菌铜锌SOD的蛋白质-蛋白质相互作用的第一个例子。
