Substitutions in the nonactive site of the passenger domain on the activity of Haemophilus influenzae immunoglobulin A1 protease.

IF 2.9 3区 医学 Q3 IMMUNOLOGY
Infection and Immunity Pub Date : 2024-08-13 Epub Date: 2024-07-11 DOI:10.1128/iai.00193-24
Chi-Wei Chen, Cheng-Hsun Ho
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Abstract

Immunoglobulin A1 (IgA1) protease is a critical virulence factor of Haemophilus influenzae that facilitates bacterial mucosal infection. This study investigates the effect of iga gene polymorphism on the enzymatic activity of H. influenzae IgA1 protease. The IgA1 protease activity was examined in the H. influenzae Rd KW20 strain and 51 isolates. Genetic variations in iga and deduced amino acid substitutions affecting IgA1 protease activity were assessed. Machine learning tools and functional complementation assays were used to analyze the effects of identified substitutions on the stability and activity of IgA1 protease, respectively. All 51 isolates exhibited similar iga expression levels. No igaB expression was detected. According to comparisons with the reference Rd KW20 strain, four substitutions in the protease domain, 26 in the nonprotease passenger domain, and two in the β-barrel domain were associated with the change in IgA1 protease activity. No substitutions in the catalytic site of IgA1 protease were observed. Logistic regression, receiver operating characteristic curves, Venn diagrams, and protein stability analyses revealed that the substitutions Asn352Lys, Pro353Ala, Lys356Asn, Gln916Lys, and Gly917Ser, which were located in the nonactive site of the passenger domain, were associated with decreases in IgA1 protease activity and stability, whereas Asn914Lys was associated with an increase in these events. Functional complementation assays revealed that the Asn914Lys substitution increased IgA1 protease activity in the Rd KW20 strain. This study identified substitutions in the nonactive site of the passenger domain that affect both the activity and stability of H. influenzae IgA1 protease.

客体结构域非活性位点的置换对流感嗜血杆菌免疫球蛋白 A1 蛋白酶活性的影响。
免疫球蛋白 A1(IgA1)蛋白酶是流感嗜血杆菌的一个关键毒力因子,可促进细菌粘膜感染。本研究探讨了 iga 基因多态性对流感嗜血杆菌 IgA1 蛋白酶酶活性的影响。研究检测了流感杆菌 Rd KW20 株和 51 个分离株的 IgA1 蛋白酶活性。评估了影响 IgA1 蛋白酶活性的 iga 基因变异和推断的氨基酸替换。利用机器学习工具和功能互补试验分别分析了已确定的取代对 IgA1 蛋白酶稳定性和活性的影响。所有 51 个分离株都表现出相似的 iga 表达水平。没有检测到igaB的表达。根据与参考Rd KW20菌株的比较,蛋白酶结构域的4个取代、非蛋白酶客体结构域的26个取代以及β-桶结构域的2个取代与IgA1蛋白酶活性的变化有关。在 IgA1 蛋白酶的催化位点上没有发现任何取代。逻辑回归、接收者操作特征曲线、文氏图和蛋白质稳定性分析表明,位于客体结构域非活性位点的 Asn352Lys、Pro353Ala、Lys356Asn、Gln916Lys 和 Gly917Ser 与 IgA1 蛋白酶活性和稳定性的降低有关,而 Asn914Lys 则与这些事件的增加有关。功能互补试验显示,Asn914Lys 的置换增加了 Rd KW20 菌株的 IgA1 蛋白酶活性。这项研究确定了客体结构域非活性位点的取代,这些取代会影响流感杆菌 IgA1 蛋白酶的活性和稳定性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Infection and Immunity
Infection and Immunity 医学-传染病学
CiteScore
6.00
自引率
6.50%
发文量
268
审稿时长
3 months
期刊介绍: Infection and Immunity (IAI) provides new insights into the interactions between bacterial, fungal and parasitic pathogens and their hosts. Specific areas of interest include mechanisms of molecular pathogenesis, virulence factors, cellular microbiology, experimental models of infection, host resistance or susceptibility, and the generation of innate and adaptive immune responses. IAI also welcomes studies of the microbiome relating to host-pathogen interactions.
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