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- Title
Comparison of Iron-Binding Ability Between Thr70-NapA and Ser70-NapA of Helicobacter pylori.
- Authors
Shan, Weiran; Kung, Hsiang‐fu; Ge, Ruiguang
- Abstract
Background The neutrophil-activating protein (NapA) of Helicobacter pylori ( H. pylori), with DNA-binding and iron seizing properties, is a fundamental virulence factor involved in H. pylori-related diseases. Compared with Ser70-NapA strain, Thr70-NapA strain is more intimately correlated with iron-deficiency anemia. Methods To investigate whether two types of proteins differ in iron-binding ability, mutated Thr70-NapA and Ser70-NapA strains were established. Isothermal titration calorimetry ( ITC) method was conducted to measure the binding between the NapA protein and Fe2+. The structural changes of NapA protein were also tested during iron interaction by fast protein liquid chromatography ( FPLC) and circular dichroism ( CD) methods. DNA-binding assay was performed for evaluate the affinity of both mutated and wild types of NapA with DNA. Results Mutated Thr70-NapA had higher iron-binding ability than wild Ser70-NapA. The structural stability of Thr70-NapA was disrupted and became more active along with the rising concentration of Fe2+, whereas no similar association was observed between Ser70-NapA and Fe2+ level. When the iron/protein molar ratio ranged from 10 to 20, both Ser70-NapA and Thr70-NapA displayed weaker DNA-binding ability. Conclusions Thr70-NapA has much stronger ability to sequester ferrous ion compared with Ser70-NapA in H. pylori. In addition, the DNA-binding property of NapA is dependent upon the Fe2+ concentration.
- Subjects
HELICOBACTER pylori; DNA-binding proteins; DNA analysis; CIRCULAR dichroism; PROTEIN analysis
- Publication
Helicobacter, 2016, Vol 21, Issue 3, p192
- ISSN
1083-4389
- Publication type
Article
- DOI
10.1111/hel.12266